JDBC (数据库连接)

/*JdbcTool.java*/

package com.qrsx.tools;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class JdbcTool {

public static void main(String[] args) {

// TODO Auto-generated method stub

}

public static Connection getConn() {

Connection conn=null;

try {

//1加载驱动

Class.forName("com.mysql.jdbc.Driver");

String url="jdbc:mysql://localhost:3306/mydb?charcterEncoding=UTF-8";

String user="root";

String password="123";

//获取连接

conn=DriverManager.getConnection(url,user,password);

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return conn;

}

public static void Close(ResultSet rs,PreparedStatement ps,Connection conn){

try {

if(rs!=null){

rs.close();}

if(ps!=null){

ps.close();}

if(conn!=null){

conn.close();
}

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

public static int exec_update(String sql,Object...para){

int i=0;

try {

Connection conn=JdbcTool.getConn();

PreparedStatement ps=conn.prepareStatement(sql);

System.out.println(para.length);

for(int j=0;j<para.length;j++){

ps.setObject(j+1, para[j]);

}

i=ps.executeUpdate();

System.out.println(i+"行受到影响!");

JdbcTool.Close(null, ps, conn);

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return i;

}

}

/*testDb*/

package com.qrsx.shop;

import java.math.BigDecimal;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import com.qrsx.tools.JdbcTool;

public class testDb {

public static void main(String[] args) {

Connection conn=JdbcTool.getConn();

String sql="select *from good";

try {

PreparedStatement ps=conn.prepareStatement(sql);

ResultSet rs=ps.executeQuery();

while(rs.next()){

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

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

System.out.print(new BigDecimal(rs.getString(3)));

System.out.println(rs.getInt(4));

}

JdbcTool.Close(rs, ps, conn);

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}
<*多重?号查询*>

public static void main(String[] args) {

JdbcTest jd=new JdbcTest();

//jd.simpleQuery();

//jd.simpleQueryByName2("java","6");

//jd.delete(3);

String sql="delete from user where id=?";

int i=JdbcTool.exec_update(sql, 7);

jd.simpleQuery();

sql="insert into user(username,password)values(?,?)";

i=JdbcTool.exec_update(sql, "张三","zhangsan");

}