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java建立连接的代码 java连接符用法

用java代码实现客户端与服务端建立连接?

套接字 Socket

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import java.net.*;

Server:

ServerSocket server=new ServerSocket(port);//port是端口

Socket socket=server.accept();

//等待客户机的连接请求,若连接,则创建一套接字,并将返回。

Client:

Socket socket=new Socket("host",port);//host主机名(本机:127.0.0.1)

java如何实现sql连接和查询的代码?

import java.sql.Connection。

import java.sql.DriverManager;  

import java.sql.PreparedStatement;  

import java.sql.ResultSet;  

import java.sql.SQLException;

import javax.naming.Context;  

import javax.naming.InitialContext;  

import javax.naming.NamingException;  

import javax.sql.DataSource;

public class DBCon {

//数据库驱动对象

public static final String DRIVER="oracle.jdbc.driver.OracleDriver";

//数据库连接地址(数据库名)

public static final String URL="jdbc:oracle:thin:@localhost:1521:orcl";

//登陆名

public static final String USER="FM";

//登陆密码

public static final String PWD="FM";

//创建数据库连接对象

private Connection con=null;

//创建数据库预编译对象

private PreparedStatement ps=null;

//创建结果集

private ResultSet rs=null;

//创建数据源对象

public static DataSource source=null;

//  //静态代码块  

//  static{  

//  

//      //初始化配置文件context  

//      try {  

//          Context context=new InitialContext();  

//          source=(DataSource)context.lookup("java:comp/env/jdbc/webmessage");  

//      } catch (Exception e) {  

//          // TODO Auto-generated catch block  

//          e.printStackTrace();  

//      }  

//  

//  

//  }

/**

* 获取数据库连接

*/

public Connection getCon(){

try {

Class.forName(DRIVER);

} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

try {

con=DriverManager.getConnection(URL,USER,PWD);

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return con;

}  

//  /**  

//   * 获取数据库连接  

//   */  

//  public Connection getCon(){  

//  

//      try {  

//          con=source.getConnection();  

//      } catch (SQLException e) {  

//          // TODO Auto-generated catch block  

//          e.printStackTrace();  

//      }  

//  

//      return con;  

//  }  

/**

* 关闭所有资源

*/

public void closeAll(){

if(rs!=null)

try {

rs.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

if(ps!=null)

try {

ps.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

if(con!=null)

try {

con.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}  

}

/**

* @param sql数据库更新(增、删、改) 语句

* @param pras参数列表(可传,可不传,不传为NULL,以数组形式存在)

* @return 返回受影响都行数

*/

public int update(String sql,String... pras){

int resu=0;

con=getCon();

try {

ps=con.prepareStatement(sql);

for(int i=0;ipras.length;i++){

ps.setString(i+1,pras[i]);

}

resu=ps.executeUpdate();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

finally{

closeAll();

}

return resu;

}

/**

* @param sql数据库查询语句

* @param pras参数列表(可传,可不传,不传为NULL,以数组形式存在)

* @return 返回结果集

*/

public ResultSet query(String sql,String... pras){

con=getCon();

try {

ps=con.prepareStatement(sql);

if(pras!=null)

for(int i=0;ipras.length;i++){

ps.setString(i+1, pras[i]);

}

rs=ps.executeQuery();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return rs;

}  

}

连接数据库的代码用java怎么做?

import java.sql.*;

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

import java.util.*;

public class inensshow extends JFrame {

private Connection connection;

private Statement statement;

private ResultSet resultSet;

private ResultSetMetaData rsMetaData;

//GUI变量定义

private JTable table;

private JTextArea inputQuery;

private JButton submitQuery;

public inensshow()

{

//Form的标题

super( "输入SQL语句,按查询按钮查看结果。" );

String url = "jdbc:mysql://localhost:3306/web";

String username = "inens";

String password = "inens";

//加载驱动程序以连接数据库

try {

Class.forName( "org.gjt.mm.mysql.Driver" );

connection = DriverManager.getConnection(

url, username, password );

}

//捕获加载驱动程序异常

catch ( ClassNotFoundException cnfex ) {

System.err.println(

"装载 JDBC/ODBC 驱动程序失败。" );

cnfex.printStackTrace();

System.exit( 1 ); // terminate program

}

//捕获连接数据库异常

catch ( SQLException sqlex ) {

System.err.println( "无法连接数据库" );

sqlex.printStackTrace();

System.exit( 1 ); // terminate program

}

//如果数据库连接成功,则建立GUI

//SQL语句

String test="SELECT * FROM data";

inputQuery = new JTextArea( test, 4, 30 );

submitQuery = new JButton( "查询" );

//Button事件

submitQuery.addActionListener(

new ActionListener() {

public void actionPerformed( ActionEvent e )

{

getTable();

}

}

);

JPanel topPanel = new JPanel();

topPanel.setLayout( new BorderLayout() );

//将"输入查询"编辑框布置到 "CENTER"

topPanel.add( new JScrollPane( inputQuery), BorderLayout.CENTER );

//将"提交查询"按钮布置到 "SOUTH"

topPanel.add( submitQuery, BorderLayout.SOUTH );

table = new JTable();

Container c = getContentPane();

c.setLayout( new BorderLayout() );

//将"topPanel"编辑框布置到 "NORTH"

c.add( topPanel, BorderLayout.NORTH );

//将"table"编辑框布置到 "CENTER"

c.add( table, BorderLayout.CENTER );

getTable();

setSize( 500, 300 );

//显示Form

show();

}

private void getTable()

{

try {

//执行SQL语句

String query = inputQuery.getText();

statement = connection.createStatement();

resultSet = statement.executeQuery( query );

//在表格中显示查询结果

displayResultSet( resultSet );

}

catch ( SQLException sqlex ) {

sqlex.printStackTrace();

}

}

private void displayResultSet( ResultSet rs )

throws SQLException

{

//定位到达第一条记录

boolean moreRecords = rs.next();

//如果没有记录,则提示一条消息

if ( ! moreRecords ) {

JOptionPane.showMessageDialog( this,

"结果集中无记录" );

setTitle( "无记录显示" );

return;

}

Vector columnHeads = new Vector();

Vector rows = new Vector();

try {

//获取字段的名称

ResultSetMetaData rsmd = rs.getMetaData();

for ( int i = 1; i = rsmd.getColumnCount(); ++i )

columnHeads.addElement( rsmd.getColumnName( i ) );

//获取记录集

do {

rows.addElement( getNextRow( rs, rsmd ) );

} while ( rs.next() );

//在表格中显示查询结果

table = new JTable( rows, columnHeads );

JScrollPane scroller = new JScrollPane( table );

Container c = getContentPane();

c.remove(1);

c.add( scroller, BorderLayout.CENTER );

//刷新Table

c.validate();

}

catch ( SQLException sqlex ) {

sqlex.printStackTrace();

}

}

private Vector getNextRow( ResultSet rs,

ResultSetMetaData rsmd )

throws SQLException

{

Vector currentRow = new Vector();

for ( int i = 1; i = rsmd.getColumnCount(); ++i )

currentRow.addElement( rs.getString( i ) );

//返回一条记录

return currentRow;

}

public void shutDown()

{

try {

//断开数据库连接

connection.close();

}

catch ( SQLException sqlex ) {

System.err.println( "Unable to disconnect" );

sqlex.printStackTrace();

}

}

public static void main( String args[] )

{

final inensshow app =

new inensshow();

app.addWindowListener(

new WindowAdapter() {

public void windowClosing( WindowEvent e )

{

app.shutDown();

System.exit( 0 );

}

}

);

}

}

------------------------------------------------------------

这次在WIN98中就不好使了。因为Mysql的驱动程序没有也没能加入到CLASSPATH 当中,但是JSP却可以使用(JSP的98驱动加载详见Jsp与Mysql连接查错文章),所以这次我是在XPServer中测试的。

java连接数据库的代码

用这个类吧.好的话,给我加加分.

import java.sql.*;

/**

* @功能: 一个JDBC的本地化API连接类,封装了数据操作方法,只用传一个SQL语句即可

* @作者: 李开欢

* @日期: 2007/

*/

public class ConnectionDemo {

/*

* 这里可以将常量全部放入另一个类中,以方便修改

*/

private static Connection conn;

private static Statement ps;

private static ResultSet rs;

private static final String DRIVER = "com.microsoft.jdbc.sqlserver.SQLServerDriver";

private static final String URL = "jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=mydb";

private static final String USER ="sa";

private static final String PASS = "sa";

public ConnectionDemo() {

// TODO Auto-generated constructor stub

ConnectionDemo.getConnection();

}

public static Connection getConnection(){

System.out.println("连接中...");

try {

Class.forName(ConnectionDemo.DRIVER);

conn = DriverManager.getConnection(ConnectionDemo.URL, ConnectionDemo.USER, ConnectionDemo.PASS);

System.out.println("成功连接");

} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return conn;

}

public static Statement getStatement(String sql){

System.out.println("执行SQL语句中...");

try {

ps = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);

if(sql.substring(0, 6).equals("select")){

rs = ps.executeQuery(sql);

System.out.println("执行完查询操作,结果已返回ResultSet集合");

}else if(sql.substring(0, 6).equals("delete")){

ps.executeUpdate(sql);

System.out.println("已执行完毕删除操作");

}else if(sql.substring(0, 6).equals("insert")){

ps.executeUpdate(sql);

System.out.println("已执行完毕增加操作");

}else{

ps.executeUpdate(sql);

System.out.println("已执行完毕更新操作");

}

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return ps;

}

public static ResultSet getResultSet(){

System.out.println("查询结果为:");

return rs;

}

public static void closeConnection(){

System.out.println("关闭连接中...");

try {

if (rs != null) {

rs.close();

System.out.println("已关闭ResultSet");

}

if (ps != null) {

ps.close();

System.out.println("已关闭Statement");

}

if (conn != null) {

conn.close();

System.out.println("已关闭Connection");

}

} catch (Exception e) {

// TODO: handle exception

}

}

public static void main(String[] args) {

// TODO Auto-generated method stub

ConnectionDemo.getConnection();

String sql = "delete from type where id = 1";

ConnectionDemo.getStatement(sql);

String sql2 = "insert into type values(1,'教学设备')";

ConnectionDemo.getStatement(sql2);

String sql1 = "select * from type";

ConnectionDemo.getStatement(sql1);

ResultSet rs = ConnectionDemo.getResultSet();

System.out.println("编号 "+"类 型");

try {

while(rs.next()){

System.out.print(" "+rs.getInt(1)+" ");

System.out.println(rs.getString(2));

}

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

ConnectionDemo.closeConnection();

}

}


标题名称:java建立连接的代码 java连接符用法
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