C++博客-★Snowhill ★-文章分类-java

eclipse快捷键

snowhill — Sun, 12 Apr 2015 14:03:00 GMT

摘要: Ctrl+1 快速修复(最经典的快捷键,就不用多说了) Ctrl+D: 删除当前行 Ctrl+Alt+↓ 复制当前行到下一行(复制增加) Ctrl+Alt+↑ 复制当前行到上一行(复制增加) Alt+↓ 当前行和下面一行交互位置(特别实用,可以省去先剪切,再粘贴了) Alt+↑ 当前行和上... 阅读全文

snowhill 2015-04-12 22:03 发表评论

linux jdk 安装报nocloassdeffounderror报错

snowhill — Wed, 25 Mar 2015 12:54:00 GMT

linux安装jdk出现java/lang/NoClassDefFoundError: java/lang/Object错误的解决方案

近日在redhat上安装jdk出现了一个莫名的错误

Error occurred during initialization of VM
java/lang/NoClassDefFoundError: java/lang/Object

辛苦google了一个小时，终于找到了解决方案

首先要确认的是环境变量的设置是否正确

相信大家都是很细心的，这方面如果有错误也会很容易发现

然而还有一个隐蔽的地方也会产生上述的错误

就是lib和jre/lib文件夹中的rt和tools是否是打包后的形式

如果发现rt.pack 和 tools.pack 那么多半问题就出在这里

解决方法也很简单，只要将相应文件解压成rt.jar 和 tools.jar

可以使用bin里面的unpack200工具

如：unpack200 rt.pack rt.jar

解压后java -version应该就没有问题了~~

snowhill 2015-03-25 20:54 发表评论

android开发三--一个最简单的登陆界面

snowhill — Sun, 06 Apr 2014 07:15:00 GMT

一新建一个项目，不建 Activity
二 res下创建一个布局文件layout

xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/login_username"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:hint="@string/hint"
        android:text="" >
    EditText>
    <EditText
        android:id="@+id/login_password"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:hint="@string/password"
        android:inputType="textPassword"
        android:text="" >
    EditText>

    <Button
        android:id="@+id/login_submit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/loginname"/>
    <TextView
        android:id="@+id/login_result"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/result"/>

LinearLayout>

三创建 src loginActivity.java文件

package com.example.basiclogin;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class loginActivity extends Activity {


        /**
         * 必须重载父类的onCreate
         */
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            this.setContentView(R.layout.login);//将布局文件与代码关联起来

            //获取布局文件中的UI元素对象
            final EditText mUserName = (EditText) this.findViewById(R.id.login_username);
            final EditText mPassword = (EditText) this.findViewById(R.id.login_password);
            Button mSubmit =  (Button)this.findViewById(R.id.login_submit);
            final TextView mResult = (TextView)this.findViewById(R.id.login_result);

            //设置按钮点击之后的事件处理
           mSubmit.setOnClickListener( new OnClickListener() {

                @Override
                public void onClick(View v) {
                    String userName = mUserName.getText().toString();
                    String password = mPassword.getText().toString();
                    if("admin".equals(userName) && "123".equals(password)){
                        mResult.setText("恭喜您，登录成功！");
                    }else{
                        mResult.setText("登录失败，用户名或密码不正确！");
                    }

        }

    } );
        }
}

四在AndroidManifest.xml声明activity

所有的Activity定义好了之后，只有在AndroidManifest.xml中声明过，才会有效。

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
           <activity android:name="loginActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            intent-filter>
     activity>
    application>

snowhill 2014-04-06 15:15 发表评论

android开发二

snowhill — Fri, 04 Apr 2014 03:57:00 GMT

当用模板生成一个hello,world apk后，该分析其结构了
工程下，以myfirst_1为例：
   myfirst_1
       |-------src--MainActivity.java
       |-------res--layout--activity_main.xml
                       --values--strings.xml
       |AnroidManifest.xml

一查看androidmanifest.xml

        <activity
            android:name="com.example.myfirst_1.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            intent-filter>
        activity>

这里可以看一个activity的定义，那啥是activity:Activity是一个容器组件，是一个承载界面，可以和用户进行交换的组件，有点类似PC上的window，但是不一样的是，通常一个Activity通常就占据了整个屏幕，而且当前只能有一个Activity与用户交互。
我们在代码src下添加了一个Activity后，必须同时在AndroidManifest.xml中声明整个activity，才是有效的。如果希望程序启动时，就打开你指定的Activity，则需要在那个activity节点当中加入

<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
intent-filter>

查看src下的mainactivity源码：

package com.example.myfirst_1;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

可以看出继承自Activity类，重载onCreate方法，onCreateOptionsMenu用于菜单创建，非必须。
查看activitymain.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView1"
        android:layout_below="@+id/textView1"
        android:text="@string/next" />

RelativeLayout>

android:id：控件的id，用于唯一确定控件。

android:layout_width，android:layout_height：控件的宽高

id的写法一般是@+id/xxxxxx, 宽高的值可以为三种之一：wrap_content, fill_parent, match_parent.

wrap_content是指，在画控件时，根据控件的实际内容来动态确定大小。

fill_parent, match_parent实际上是一个意思，占满父容器的空间，区别只是match_parent是在Android2.2之后引进的。

android:text 是控件的文本内容，值可以直接填写，也可以引用values/strings.xml下的定义。例如

android:text="@string/next" 就是引用了res/values/strings.xml下的：

<resources>

    <string name="app_name">myfirst_1string>
    <string name="action_settings">Settingsstring>
    <string name="hello_world">Hello world!string>
    <string name="next">下一步string>
resources>

如果这里不用这种引用，编译会出现一个警告should use @string resource

snowhill 2014-04-04 11:57 发表评论

andorid开发环境准备

snowhill — Thu, 03 Apr 2014 08:01:00 GMT

一　安装jdk,android sdk
安装说明：http://developer.android.com/sdk/index.html
下载http://dl.google.com/android/android-sdk_r22-windows.zip
设置Android SDK的Path环境变量，方便一些工具命令的调用，设置步骤同JDK。添加sdk路径下的两个文件夹tools和　platform-tools到Path环境变量（例如G:\software\java\android-sdk-windows\tools;
G:\software\java\android-sdk-windows\platform-tools）。
检查环境变量是否成功 : cmd 下运行 android -h
再运行SDK Manager.exe

二　运行eclipse，安装ADT插件
安装说明：http://developer.android.com/sdk/installing/installing-adt.html
a.启动Eclipse,然后选择Help（帮助）>InstallNewSoftware（安装更新软件）...
输入：
ADTplugin
https://dl-ssl.google.com/android/eclipse/
b 本地安装
下载http://dl.google.com/android/ADT-22.6.2.zip
和a一个地方输入：
jar:file:/f:/software/java/ADT-15.0.0.zip.zip
安装完成成后需要重启eclipse
配置ADT：
a.选择Window（窗口）>Preferences（首选项）...打开Preferences（首选项）
b.选择左边面板里的Android。你可能会看到一个对话框询问你是否想要发送使用信息给Google。做出你的选择，然后点Proceed。
c.SDKLocation在主面板中出现，点击Browse（浏览）...，然后找到你下载的SDK路径，点击确定。
d.点击Apply（应用），Done（完成）！然后就OK。

三配置模拟器

snowhill 2014-04-03 16:01 发表评论

java gui设计

snowhill — Fri, 11 Oct 2013 14:24:00 GMT

摘要: java 代码 Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->import javax.swing.* ;import java.awt.*;import java.awt.event.*;import&nb... 阅读全文

snowhill 2013-10-11 22:24 发表评论

java blob写出

snowhill — Mon, 30 Sep 2013 15:34:00 GMT

import java.sql.*;
import java.io.*;
import java.util.*;
/**
* @author semovy 测试向oracle 读,写文件Blob 读,写大文本Clob
*/
public class OracleBlobTest {

public static void main(String[] args) {
    if (args.length<2)
    {
        System.out.println("usage: java OracleBlobTest [tablename][columname]");
        System.exit(1);
    }
String table_name=args[0];
String column_name=args[1];
OracleBlobTest obt = new OracleBlobTest();
// obt.writeBlob("blob_content","id");
//写出数据库内容
   obt.readBlob(table_name,column_name);
   //写入数据库内容
//obt.writeBlob("E:\\img\\2011\\DSC01333.JPG");
//obt.readClob();
}
/**
*   * 从数据库里读取blob字段写出到文件
*/
private void readBlob(String tablename,String columname) {
Connection conn = null;
try {
   conn = getConnection();
   String sql = "select * from "+tablename+" where "+columname+"=?";
   PreparedStatement stmt = conn.prepareStatement(sql);
   stmt.setString(1,"1");
   ResultSet rs = stmt.executeQuery();
   int tempLen = 0;
   int amount = 0;
   if (rs.next()) {
   String colVal=rs.getString("file_name");
   colVal=colVal.replaceAll("\\\\","\\\\\\\\");
   colVal=colVal.replaceAll(" ","");
   System.out.println(colVal);
   File file=new File(colVal);
   byte[] buffer = new byte[1024];
   OutputStream out = new FileOutputStream(file);
   Blob blob = rs.getBlob("blob_column");
   InputStream in = blob.getBinaryStream();
   while ((tempLen = in.read(buffer)) != -1) {
   out.write(buffer, 0, tempLen);
   amount += tempLen;
   System.out.println("已经读出并写:" + amount + " 字节");
   }
   System.out.println("已经读出并写:完成");
   out.flush();
   out.close();
   in.close();
   rs.close();
   stmt.close();
   }
} catch (ClassNotFoundException e) {
   System.out.println(e.getLocalizedMessage());
} catch (SQLException e) {
   System.out.println(e.getLocalizedMessage());
} catch (IOException e) {
   System.out.println(e.getLocalizedMessage());
} finally {
   try {
    if (conn != null)
     conn.close();
   } catch (SQLException e) {
    System.out.println(e.getLocalizedMessage());
   }
}
}

/**
* 从二进制文件写到数据库
*/
private void writeBlob(String filename) {
Connection conn = null;
try {
   conn = getConnection();
   conn.setAutoCommit(false);
   String sql = "insert into blob_content values(?,?,?)";
   PreparedStatement stmt = conn.prepareStatement(sql);
   System.out.println(filename);
   stmt.setString(1,filename);
   File file=new File(filename);
   FileInputStream fis=new FileInputStream(file);
   stmt.setBinaryStream(2,fis,fis.available());
   stmt.setString(3,"11");
   stmt.executeUpdate();
   conn.commit();
   /*
   if (rs.next()) {
    OutputStream out = ((oracle.sql.BLOB) blob).setBinaryStream(0);// 从0开始,否则写出的文件有差错
    int bufferSize = ((oracle.sql.BLOB) blob).getBufferSize();
    System.out.println("bufferSize :" + bufferSize);
    BufferedInputStream in = new BufferedInputStream(new FileInputStream(colVal), bufferSize);
    byte[] b = new byte[bufferSize];
    int count = in.read(b, 0, bufferSize);
    int amount = 0;
    while (count != -1) {
     out.write(b, 0, count);
     amount += count;
     System.out.println("处理了 " + amount + " 字节");
     count = in.read(b, 0, bufferSize);
     System.out.println("处理了 " + amount + " 字节,成功");
}

    out.close();
    out = null;
    in.close();
    conn.commit();
}
*/
stmt.close();

} catch (ClassNotFoundException e) {
   System.out.println(e.getLocalizedMessage());
} catch (SQLException e) {
   try {
    conn.rollback();
   } catch (SQLException e1) {
    System.out.println(e1.getLocalizedMessage());
   }
   System.out.println(e.getLocalizedMessage());
} catch (IOException e) {
   System.out.println(e.getLocalizedMessage());
} finally {
   try {
    if (conn != null)
     conn.close();
   } catch (SQLException e) {
    System.out.println(e.getLocalizedMessage());
   }
}
}

/**
* 读大文本
*
*/
private void readClob() {
Connection conn = null;
try {
   conn = getConnection();
   Statement stmt = conn.createStatement();
   ResultSet rs = stmt.executeQuery("select * from test where id=2");
   String tempStr = null;
   if (rs.next()) {
    Clob clob = rs.getClob("CLOBCONTENT");
    if (clob != null) {
     Reader in = clob.getCharacterStream();
     BufferedReader br = new BufferedReader(in);
     System.out.println("开始读....");
     while ((tempStr = br.readLine()) != null) {
      System.out.println(tempStr);
     }
     System.out.println("读完成....");
     in.close();
    }
    rs.close();
    stmt.close();
   }
} catch (ClassNotFoundException e) {
   System.out.println(e.getLocalizedMessage());
} catch (SQLException e) {
   System.out.println(e.getLocalizedMessage());
} catch (IOException e) {
   System.out.println(e.getLocalizedMessage());
} finally {
   try {
    if (conn != null)
     conn.close();
   } catch (SQLException e) {
    System.out.println(e.getLocalizedMessage());
   }
}
}

/**
* 写大文本
*
*/
private void writeClob() {
Connection conn = null;
try {
   conn = getConnection();
   conn.setAutoCommit(false);
   String sql = null;
   Statement stmt = conn.createStatement();
   sql = "delete from clob_content ";
   stmt.executeUpdate(sql);
   sql = "insert into clob_content values('test',empty_clob())";
   stmt.executeUpdate(sql);
   ResultSet rs = stmt.executeQuery("select * from clob_content");
   if (rs.next()) {
    Clob clob = rs.getClob("CLOB_COLUMN");
    PrintWriter out = new PrintWriter(new BufferedWriter(
      ((oracle.sql.CLOB) clob).setCharacterStream(0)));
    BufferedReader in = new BufferedReader(new InputStreamReader(
      new FileInputStream(
        "d:\\javasource\\db\\textcontent.txt")));
    String str = null;
    System.out.println("开始写...");
    while ((str = in.readLine()) != null) {
     out.println(str);
     System.out.println(str);
    }
    in.close();
    out.close();
    rs.close();
    conn.commit();
   }

public Connection getConnection() throws ClassNotFoundException,IOException,
     SQLException {
Properties ps=new Properties();
FileInputStream fis= new FileInputStream("mydb.properties");
ps.load(fis);
fis.close();
String url=ps.getProperty("db_url");
String user=ps.getProperty("username");
String pwd=ps.getProperty("password");
     String driver = "oracle.jdbc.driver.OracleDriver";
Class.forName(driver);
     return DriverManager.getConnection(url, user, pwd);
}

/**
* @param rs
* @throws SQLException
*/
private void displayResultSet(ResultSet rs) throws SQLException {
ResultSetMetaData rsmd = rs.getMetaData();
int colnum = rsmd.getColumnCount();
while (rs.next()) {
   for (int i = 0; i < colnum; i++) {
    if (i == colnum - 1)
     System.out.print(rsmd.getColumnLabel(i + 1) + ": "
       + rs.getObject(i + 1));
    else
     System.out.print(rsmd.getColumnLabel(i + 1) + ": "
       + rs.getObject(i + 1) + " , ");
   }
   System.out.println();
}
}
}
mydb.properties文件
db_url=jdbc:oracle:thin:@127.0.0.1:1521:ccxe
username=scott
password=test

snowhill 2013-09-30 23:34 发表评论

java 从oracle取数据生成xml文件

snowhill — Tue, 24 Sep 2013 14:43:00 GMT

import java.sql.*;
import java.util.Scanner;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.FileOutputStream;
class testdb1
{
    public static void main(String args[]) {
    try {
      Class.forName("oracle.jdbc.driver.OracleDriver");
    } catch (Exception e) {
    System.out.println("异常"+e.getMessage());
    System.exit(1);
    }

    if (args.length<7)
    {
        System.out.println("usage: java testdb1 [ip][sid][username][passwd][tablename][columname][djbh]");
        System.exit(1);
    }
    //定义数据库对象
    Connection conn = null;
    PreparedStatement stmt = null;
    ResultSet rset = null;
    ResultSet rs = null;

        try {
            Scanner s=new Scanner(System.in);
          // System.out.println("请输入用户名:");
            String username=args[2];
           // System.out.println("请输入密码:");
            String passwd=args[3];
           // System.out.println("请输入要生成的表名:");
            //String tablename=s.nextLine();
            String tablename=args[4];
            String columname=args[5];
            String file_name=args[6];
           // System.out.println("请输入字段名:");
          // String columname=s.nextLine();
           // System.out.println("请输入你要生成的xml文件的单据编号:");
           // String file_name=s.nextLine();
            String xmlFile =file_name+".xml";

            //String sql=args[3];

      conn = DriverManager.getConnection("jdbc:oracle:thin:@"+args[0]+":1521:"+args[1], username,passwd);
      //get database metadata
      DatabaseMetaData dbmd = conn.getMetaData();

    try {
      /*          //文本创建
      if (!xmlFile.isFile())
      {
      xmlFile.createNewFile();
      }

     //以下生成的gb2312
      FileWriter fw = new FileWriter(xmlFile);
      fw.write(""+"\n");
      fw.write(""+"\n");
      fw.write("\t"+""+"\n");
   fw.write("\t"+"\t"+""+"\n");
      fw.write("\t"+"\t"+""+"\n");
      */
      //生成UTF-8文件
      // OutputStreamWriter out = new OutputStreamWriter(new FileOutputStream(path),"UTF-8");
      OutputStreamWriter fw = new OutputStreamWriter(new FileOutputStream(xmlFile),"UTF-8");
      fw.write(""+"\n");
      fw.write(""+"\n");
      fw.write("\t"+""+"\n");
   fw.write("\t"+"\t"+""+"\n");
      fw.write("\t"+"\t"+""+"\n");

      stmt = conn.prepareStatement("select * from "+tablename+" where "+columname+"=?") ;
      //corporderid
         //Execute the query to populate the ResultSet
      stmt.setString(1,file_name);
      rs = stmt.executeQuery();
         //stmt = conn.createStatement();
         // rs=stmt.executeQuery("select * from "+tablename);
    //get resultset metadata
        ResultSetMetaData rsData = rs.getMetaData();
        int columncount=rsData.getColumnCount();
    while (rs.next())
      {
      fw.write("\t"+"   for (int i=1; i    {
            String colName=rsData.getColumnName(i);
            String colVal=rs.getString(i);
            //System.out.println("<"+colName+">");
            fw.write(colName+"=\"");
            if (colVal != null && !colVal.equals("")) {
            fw.write(colVal);
             }
            else{
            fw.write("");
            };
            fw.write("\" ");
      }
       fw.write(">"+"\n");
      }
      fw.write("\n"+"\t"+"\t"+""+"\n");
      fw.write("\t"+"\t"+""+"\n");
      fw.write("\t"+""+"\n");
      fw.write(""+"\n");

     fw.flush();
     fw.close();
     rs.close();
                  } catch (Exception e) {
          e.printStackTrace();
       }
    }
catch (SQLException e) {
      System.out.println("Darn! A SQL error: " + e.getMessage());
    }

}
}

snowhill 2013-09-24 22:43 发表评论

java 对xml文件的操作二--使用Marshaller

snowhill — Mon, 23 Sep 2013 14:43:00 GMT

//package com.helloweenvsfei.xml;

import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlRootElement;
public class JAXBDemo {
public static void main(String[] args) {
  // 创建xml文档对象，其保存在d盘
  File xmlFile = new File("d:\\javasource\\xml\\test.xml");
  //声明JAXBContext上下文对象
  JAXBContext context;
  try {
   //通过指定映射的类创建上下文
   context = JAXBContext.newInstance(Article.class);
  //通过上下文创建java转化xml的对象Marshaller
  Marshaller m = context.createMarshaller();
  //创建xml中的数据
  Article article = new Article();
  article.setAuthor("Janet");
  article.setDate("20080801");
  article.setEmail("janetvsfei@yahoo.com.cn");
  article.setTitle("XML");
  //将java对象转化到xml
  m.marshal(article, xmlFile);

   //通过上下文创建xml转化java的对象Unmarshaller
//   Unmarshaller u = context.createUnmarshaller();
//   Article article = (Article)u.unmarshal(xmlFile);
//   System.out.println(article.getAuthor());
//   System.out.println(article.getDate());
//   System.out.println(article.getEmail());
//   System.out.println(article.getTitle());
  } catch (JAXBException e) {
   e.printStackTrace();
  }

}

@XmlRootElement
class Article {

private String title;

private String author;

private String email;

private String date;

public String getTitle() {
return title;
}

public void setTitle(String title) {
this.title = title;
}

public String getAuthor() {
return author;
}

public void setAuthor(String author) {
this.author = author;
}

public String getEmail() {
return email;
}

public void setEmail(String email) {
this.email = email;
}

public String getDate() {
return date;
}

public void setDate(String date) {
this.date = date;
}

}

snowhill 2013-09-23 22:43 发表评论

java 对xml的操作--jdk 1.6之前

snowhill — Wed, 04 Sep 2013 09:59:00 GMT

package xml;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.Iterator;
import java.util.Vector;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
public class DomTest {
Vector students_Vector;
private Vector readXMLFile(String file) throws Exception {
if(file == null){
System.out.println("没找到文件!");
System.exit(1);
}
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = dbf.newDocumentBuilder();
Document doc = builder.parse(file); // 获取到xml文件
Element root = doc.getDocumentElement(); // 获取根元素
NodeList students = root.getElementsByTagName("学生");
students_Vector = new Vector();
for (int i = 0; i < students.getLength(); i++) {
   // 一次取得每一个学生元素
   Element ss = (Element) students.item(i);
   // 创建一个学生的实例
   student stu = new student();
   stu.setSex(ss.getAttribute("性别"));
   NodeList names = ss.getElementsByTagName("姓名");
   Element e = (Element) names.item(0);
   Node t = e.getFirstChild();
   stu.setName(t.getNodeValue());
   NodeList ages = ss.getElementsByTagName("年龄");
   e = (Element) ages.item(0);
   t = e.getFirstChild();
   stu.setAge(Integer.parseInt(t.getNodeValue()));
   students_Vector.add(stu);
}
return students_Vector;
}
// 写入ｘｍｌ文件
public static void callWriteXmlFile(Document doc, Writer w, String encoding) {
try {
   Source source = new DOMSource(doc);
   Result result = new StreamResult(w);
   Transformer xformer = TransformerFactory.newInstance()
     .newTransformer();
   xformer.setOutputProperty(OutputKeys.ENCODING, encoding);
   xformer.transform(source, result);
} catch (TransformerConfigurationException e) {
   e.printStackTrace();
} catch (TransformerException e) {
   e.printStackTrace();
}
}
private void writeXMLFile(String outfile) {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = null;
try {
   builder = dbf.newDocumentBuilder();
} catch (Exception e) {
}
Document doc = builder.newDocument();
Element root = doc.createElement("学生花名册");
doc.appendChild(root); // 将根元素添加到文档上
// 获取学生信息
for (int i = 0; i < students_Vector.size(); i++) {
   student s = (student) students_Vector.get(i);
   // 创建一个学生
   Element stu = doc.createElement("学生");
   stu.setAttribute("性别", s.getSex());
   root.appendChild(stu);// 添加属性
   // 创建文本姓名节点
   Element name = doc.createElement("姓名");
   stu.appendChild(name);
   Text tname = doc.createTextNode(s.getName());
   name.appendChild(tname);

   //创建文本年龄节点
   Element age = doc.createElement("年龄");
   stu.appendChild(age); // 将age添加到学生节点上
   Text tage = doc.createTextNode(String.valueOf(s.getAge()));
   age.appendChild(tage); // 将文本节点放在age节点上
}
try {
   FileOutputStream fos = new FileOutputStream(outfile);
   OutputStreamWriter outwriter = new OutputStreamWriter(fos);
   // ((XmlDocument)doc).write(outwriter); //出错！
   callWriteXmlFile(doc, outwriter, "gb2312");
   outwriter.close();
   fos.close();
} catch (Exception e) {
   e.printStackTrace();
}
}
public static void main(String args[]) {
String str = "c:\\java\\test.xml";
DomTest t = new DomTest();
try {
   Vector v = t.readXMLFile(str);
   Iterator it = v.iterator();
   while (it.hasNext()) {
    student s = (student) it.next();
    System.out.println(s.getName() + "\t" + s.getAge() + "\t"
      + s.getSex());
   }
} catch (Exception e) {
   e.printStackTrace();
}
String outfile = "stucopy.xml";
t.writeXMLFile(outfile);
}
}

class student{
private String sex;
private String name;
private int age;

public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public void setSex(String s){sex=s;}
public String getSex(){return sex;}

public void setName(String n){name=n;}
public String getName(){return name;}
}
编译：javac -d . DomTest.java
调用：java xml.DomTest

snowhill 2013-09-04 17:59 发表评论

java 中oracle 更新批处理

snowhill — Wed, 11 Apr 2012 14:48:00 GMT

与常规的jdbc更新处理只多了一个设置批值的步聚，相关代码如下：

    import java.sql.*;
import oracle.jdbc.*;
public class javabatch {

    public static final int TOTAL_NUM_ROWS=2000;
    public static final int BATCH_SIZE=10;

    public static void main (String [] args) throws SQLException
    {
        DriverManager.registerDriver(new OracleDriver());
        Connection myconnection =DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:progather",
        "username",
        "passord");

        myconnection.setAutoCommit(false);
        Statement mystatement=myconnection.createStatement();
        mystatement.execute("truncate table tmp_cxf_1");

        System.out.println("Insert into table tmp_cxf_1 "+TOTAL_NUM_ROWS+" without batching");
        insertrows(myconnection,false);
        System.out.println("Insert into tmp_cxf_1 with update batching");
        insertrows(myconnection,true);
        mystatement.close();
        myconnection.close();

    }//end of main

    public static void insertrows(Connection myconnection,boolean batching) throws SQLException
    {
        OraclePreparedStatement myoracleprepastatment =(OraclePreparedStatement)myconnection.prepareStatement("insert into tmp_cxf_1 (ind_code,sec_code) values (?,?)");
        if (batching)
        {
            System.out.println("setting the batch value to "+BATCH_SIZE);
            myoracleprepastatment.setExecuteBatch(BATCH_SIZE);
        }
        System.out.println("batch value="+myoracleprepastatment.getExecuteBatch());
        long start_time=System.currentTimeMillis();
        for (int count=0;count<TOTAL_NUM_ROWS;count++)
        {
            myoracleprepastatment.setInt(1, count);
            myoracleprepastatment.setInt(2, count+100);
            int rowsInserted=myoracleprepastatment.executeUpdate();
        }
        long end_time=System.currentTimeMillis();
        System.out.println("Total time for inserting "+TOTAL_NUM_ROWS+"rows was "+(end_time-start_time)+" millsceconds");
        myconnection.rollback();
        myoracleprepastatment.close();

    }//insertrows
}

snowhill 2012-04-11 22:48 发表评论

jdbc连接池的使用

snowhill — Thu, 05 Apr 2012 14:23:00 GMT

import java.sql.*;
import javax.sql.*;

import oracle.jdbc.pool.OracleConnectionPoolDataSource;
public class jdbc {

    public static void main(String args[]) {

        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
        } catch (Exception e) {
            System.out.println("异常" + e.getMessage());
            System.exit(1);
        }

        try {
            //create connection pool data source object
            OracleConnectionPoolDataSource myOCPDS=new OracleConnectionPoolDataSource();

            myOCPDS.setServerName("192.168.12.20");
            myOCPDS.setDatabaseName("progather");
            myOCPDS.setPortNumber(1521);
            myOCPDS.setDriverType("thin");
            myOCPDS.setUser("username");
            myOCPDS.setPassword("password");

            System.out.println("create a pool connection");
            PooledConnection myPooledConnection=myOCPDS.getPooledConnection();

            System.out.println("request a connection instance");
            Connection myconnection=myPooledConnection.getConnection();
            Displaycustomer(myconnection,401203410);
            myconnection.close();
            System.out.println("close the connection instance");

            System.out.println("request another connection");
            myconnection=myPooledConnection.getConnection();
            Displaycustomer(myconnection,401203411);
            myconnection.close();
            System.out.println("close another connection instance");
            myPooledConnection.close();


        } catch (SQLException e) {
            System.out.println("Darn! A SQL error: " + e.getMessage());
        }
    }

    public static void Displaycustomer(Connection myconnection,int id) throws SQLException
    {
        Statement mystatement=myconnection.createStatement();
        String sql;
        int org_uni_code;
        String chi_short_name;
        String org_chi_name;
        sql="select org_uni_code,chi_short_name,org_chi_name from ccxe2.pub_org_info where area_uni_code="+id;
        ResultSet myresultset=mystatement.executeQuery(sql);
        while(myresultset.next())
        {
            org_uni_code=myresultset.getInt("org_uni_code");
            chi_short_name=myresultset.getString("chi_short_name");
            org_chi_name=myresultset.getString("org_chi_name");
            System.out.println("org_unit_code is "+org_uni_code+"    chi_short_name:" + chi_short_name+
                    "    org_chi_name:"+ org_chi_name);
            }
        myresultset.close();
        mystatement.close();
    }
}

snowhill 2012-04-05 22:23 发表评论

myeclipse 中svn插件加载

snowhill — Fri, 30 Mar 2012 03:19:00 GMT

1、从官网下载site-1.6.9.zip文件,网址是:subclipse.tigris.org,
2、从中解压出features与plugins文件夹，复制到E:\MyEclipse\myPlugin\svn里面，其它的*.xml文件不要。
3、在E:\MyEclipse\MyEclipse8\dropins下新建文件svn.link,内容是:path=E:\\MyEclipse\\myPlugin\\svn保存。
4、删除E:\MyEclipse\MyEclipse8.5\configuration\org.eclipse.update文件夹
5、重启myeclipse就一切正常了。

snowhill 2012-03-30 11:19 发表评论

java blob/clob

snowhill — Mon, 19 Mar 2012 16:12:00 GMT

//2012-03-18　针对oracle 数据库中大对象的读写 getBinaryOutPutStream()

import java.sql.*;
import java.io.*;
//声明clob/blob必须要导入oracle.sql.*
import oracle.sql.*;
public class jdbc_blob {

  public static void main (String args[]) throws SQLException,IOException {

    try {
      Class.forName("oracle.jdbc.driver.OracleDriver");
    } catch (Exception e) {
      System.out.println("异常"+e.getMessage());
      System.exit(1);
    }

    Connection conn = null;
    Statement stmt = null;
    ResultSet rset = null;
    ResultSet rs = null;
    //定义文件存放
    String sourceDirectory="d:\\javasource\\db\\";
    //String filename=sourceDirectory+"textecontent.txt";
    try {
      conn = DriverManager.getConnection(
          "jdbc:oracle:thin:@192.168.1.102:1521:ccxe", "scott", "test");
        //diable auto commit;
        conn.setAutoCommit(false);

        //建立statement 对象
        stmt=conn.createStatement();
        writeCLOB(stmt,sourceDirectory+"textcontent.txt");
        writeBLOB(stmt,sourceDirectory+"Java_jdbc数据库连接池总结.doc");
        //addBFILE(stmt,"SAMPLE_FILE_DIR","textcontent.txt");
        //addBFILE(stmt,"SAMPLE_FILE_DIR","Java_jdbc数据库连接池总结.doc");
        stmt.close();
        conn.close(); //关闭数据库连接
      } catch (SQLException e)
          {
            System.out.println("Darn! A SQL error: " + e.getMessage());
         }
  }
//定义方法。
private static void writeCLOB(Statement stmt,String filename) throws SQLException,IOException
    {
    stmt.executeUpdate("insert into clob_content(file_name,clob_column)"+" values ('"+filename+"',EMPTY_CLOB())");
    ResultSet clobResultSet=stmt.executeQuery("select clob_column from clob_content ");
    if (    clobResultSet.next()){
    Clob myClob= clobResultSet.getClob("clob_column");
BufferedReader myBufferedReader = new BufferedReader( new InputStreamReader(new FileInputStream(filename)));
PrintWriter out = new PrintWriter(new BufferedWriter(((oracle.sql.CLOB) myClob).setCharacterStream(0)));
String str=null;
System.out.println("开始写");
while ((str=myBufferedReader.readLine())!=null)
{
    //myClob.putChars(position,textBuffer);
    out.println(str);
    System.out.println(str);
    //position+=charsRead;
}
out.close();
myBufferedReader.close();
stmt.execute("commit");
    }//end if
System.out.println("write content from file" + filename+" to clob");
}//end of writeCLOB;

private static void writeBLOB(Statement stmt,String filename) throws SQLException,IOException
{
    stmt.executeUpdate("insert into blob_content (file_name,blob_column)"+" values (' "+filename +"', EMPTY_BLOB())");
    System.out.println(filename);
    ResultSet blobResultSet=stmt.executeQuery("select blob_column from blob_content ");
    System.out.println(blobResultSet.next());
    if(blobResultSet.next()){
    Blob myBlob=blobResultSet.getBlob("blob_column");
    OutputStream out=myBlob.setBinaryStream(0);
    int chunksize=((oracle.sql.BLOB)myBlob).getBufferSize();
    byte[] byteBuffer=new byte[chunksize];
    //FileInputStream myFileInputStream=new  FileInputStream(filename);
    BufferedInputStream in = new BufferedInputStream(new FileInputStream(filename), chunksize);
    int count = in.read(byteBuffer, 0, chunksize);
    int bytesRead=0;
    System.out.println(count);
        while(count!=-1)
    {
    out.write(byteBuffer,0, count);
    bytesRead+=count;
     System.out.println("处理了 " + bytesRead + " 字节");
     count = in.read(byteBuffer, 0, chunksize);
     System.out.println("处理了 " + bytesRead + " 字节,成功");

    //    myBlob.putBytes(position,byteBuffer);
    //    position+=bytesRead;
    }
        out.close();
    in.close();
    stmt.execute("commit");

    }
    System.out.println("write content from file"+filename+"to blob");
}// end of writeBLOB();

private static void addBFILE(Statement stmt,String directory,String filename) throws SQLException{
    String sql;
    sql="insert into bfile_content(file_name,bfile_column)"+" values ('"+filename +"',"+"BFILENAME('"+directory+"','"+filename+"'))";
    System.out.println(sql);
    stmt.executeUpdate (sql);
    stmt.execute("commit");
    System.out.println("added pointer to file "+filename+" to BFILE in database directory  "+directory);
}// end of addbfile();
}

当然。前期你得准备相关表和文件

snowhill 2012-03-20 00:12 发表评论

java - log4j

snowhill — Fri, 16 Mar 2012 14:27:00 GMT

一下载log4j类。
http://www.apache.org/dyn/closer.cgi/logging/log4j/1.2.16/apache-log4j-1.2.16.zip
放到你定义的classpath中去
二编写log4j.properties，放到你class文件生成的目录
#定义输出级别
log4j.rootLogger=ERROR,A1
#指定布局以控制台形式输出
log4j.appender.A1=org.apache.log4j.ConsoleAppender
#自适应输出方式
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
#定义输出样式%L 输出错误所在行数 %c:类的全名 %m 具体信息 %n 换行
log4j.appender.A1.layout.ConversionPattern=%-4r %-5p %L %d{yyyy-MM-dd HH:mm:ssS} %c %m%n
三编写测试程序

import org.apache.log4j.Logger;
import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Level;
public class Log4jTest {
    public static void main(String[] args){
     Logger log=Logger.getLogger(Log4jTest.class);
        for (int i=0;i<100;i++)
        {
            for (int j=0;j<100;j++ )
            {
                if (log.isDebugEnabled())
                {
                    log.debug("开始计算"+i+"*"+j+"次运算!");
                }
            //    log.warn("以warn级别的输出!");
            }
            //log.error("以error级别的输出!");
        }

    }//end main
}

参考：
http://www.blogjava.net/hwpok/archive/2008/08/23/223891.html
http://logging.apache.org/log4j/1.2/manual.html

snowhill 2012-03-16 22:27 发表评论

java 存储过程调用

snowhill — Thu, 08 Mar 2012 15:41:00 GMT

import java.sql.*;

public class jdbc_prc {

  public static void main(String args[]) {

    try {
      Class.forName("oracle.jdbc.driver.OracleDriver");
    } catch (Exception e) {
      System.out.println("异常"+e.getMessage());
      System.exit(1);
    }

    Connection conn = null;
    Statement stmt = null;
    ResultSet rset = null;
    ResultSet rs = null;
    //PreparedStatement pstmt;
    String sql;
    try {
      conn = DriverManager.getConnection(
          "jdbc:oracle:thin:@127.0.0.1:1521:ccxe", "scott", "test");

        //conn.prepareStatement
        CallableStatement myCallableStatement=conn.prepareCall(
            "{call update_salgrade(?,?,?)}"
        );
        myCallableStatement.setInt(1,7);
        myCallableStatement.setInt(2,8000);
        myCallableStatement.setInt(3,9000);
        myCallableStatement.execute();
        myCallableStatement.close();

      conn.close(); //关闭数据库连接
      conn = null;
    } catch (SQLException e) {
      System.out.println("Darn! A SQL error: " + e.getMessage());
    } finally {
      if (rset != null)
        try {
          rset.close();
        } catch (SQLException ignore) {
        }
      if (stmt != null)
        try {
          stmt.close();
        } catch (SQLException ignore) {
        }
      if (conn != null)
        try {
          conn.close();
        } catch (SQLException ignore) {
        }
    }
  }
}

snowhill 2012-03-08 23:41 发表评论

java 网络间的文件传输

snowhill — Sun, 26 Feb 2012 03:28:00 GMT

使用socket套接字，文件输出流对象写入文件

import java.net.*;
import java.io.*;

public class file_client
{
    int i;
    static int port;
    static String iaddr;
    static String infilename;
    public file_client(){
    try
    {

        Socket socket =new Socket(InetAddress.getByName(iaddr),port);
        DataOutputStream outstream=new DataOutputStream(socket.getOutputStream());
        FileInputStream fis =new FileInputStream(infilename);

        //
        while ((i=fis.read())!=-1)

        {
            outstream.writeInt(i);
        }
        outstream.writeInt(i);
        System.out.println("data transfer sucessfully!");
        socket.close();

    }
    catch (IOException e)
    {
        System.out.println(e.getMessage());

    }
    }

public static void main(String args[])
{
    if (args.length<3)
    {
        System.out.println("usage: java file_server [IP] [port] [filename]");
        System.exit(1);
    }
    iaddr=args[0];
    port=Integer.parseInt(args[1]);
    infilename=args[2];
    file_client serverstart=new file_client();
}
}

以上为客户端代码,下为服务端代码：

编译javac file_server.java
javac file_client.java
测试：
服务端：java file_server 2022 77.txt
客户端 java file_client 192.168.1.102 2022 file_client.java

snowhill 2012-02-26 11:28 发表评论

java 输入输出与socket

snowhill — Wed, 16 Nov 2011 15:39:00 GMT

摘要: Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->//一个创建socket的例子import java.net.*;import java.io.*;class server{ ... 阅读全文

snowhill 2011-11-16 23:39 发表评论