04、JDBC范例

范例：JDBC查询

package com.hsp;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.Statement;

import java.util.Date;

public class testDatabase {

/**

* @param args

*/

public static void main(String[] args) {

Connection con = null;

String DBname = "jdb"; //数据库名字

String url = "jdbc:mysql://localhost:3306/"+DBname+"?useSSL=true&characterEncoding=utf-8";

String username = "root";//数据库账号

String password = "root";//数据库密码

Statement sql = null;

ResultSet rs = null;

try {

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

con = DriverManager.getConnection(url, username, password);//连接代码

sql = con.createStatement();

rs = sql.executeQuery("SELECT * FROM students");//查询student表中的数据

while(rs.next()){

String number = rs.getString(1);

String name = rs.getString(2);

Date date = rs.getDate(3);

float height = rs.getFloat(4);

System.out.println("number:"+number+" name:"+name+" date:"+date+" height:"+height);

}

con.close();//con必须等rs调用完数据后才能关闭，否则查询不到数据

} catch (Exception e) {

// TODO: handle exception

System.out.println(e);

}

}

}

范例：封装JDBC查询

package com.hsp;

import java.sql.*;

public class JdbcMysql {

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

// TODO Auto-generated method stub

Connection con = null;

Statement sql = null;

ResultSet rs = null;

con = GetDBConnection.ConnectDB("jdb", "root", "root");

String query = "SELECT * FROM STUDENTS";

if(con==null){

System.out.println("连接错误");

return ;

}

try {

sql = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);

rs = sql.executeQuery(query);

rs.last();

int max = rs.getRow();

System.out.println("表共有"+max+"条记录"+",随机抽取2条记录");

int a[] = GetRandomNmber.getRandomNumber(max,2);

for(int i:a){

rs.absolute(i);

String number = rs.getString(1);

String name = rs.getString(2);

Date date = rs.getDate(3);

float height = rs.getFloat(4);

System.out.println("number:"+number+" name:"+name+" date:"+date+" height:"+height);

}

con.close();

} catch (Exception e) {

// TODO: handle exception

System.out.println(e);

}

}

}

package com.hsp;

import java.sql.Connection;

import java.sql.DriverManager;

public class GetDBConnection {

public static Connection ConnectDB(String DBname,String username,String password) {

Connection con = null;

String url = "jdbc:mysql://localhost:3306/"+DBname+"?useSSL=true&characterEncoding=utf-8";

try {

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

con = DriverManager.getConnection(url, username, password);

} catch (Exception e) {

// TODO: handle exception

System.out.println(e);

}

return con;

}

}

package com.hsp;

import java.util.Random;

public class GetRandomNmber {

public static int[] getRandomNumber(int max,int amount){

//1至max之间的amount个不同随机整数 包括(1和max)

int [] randomNumber = new int[amount];

int index = 0;

randomNumber[0] = -1;

Random random = new Random();

while(index<amount){

int number = random.nextInt(max)+1;

boolean  isInArrays = false;

for(int m:randomNumber){//m依次去数组randomNumber元素的值

if(m==number)

isInArrays = true;//number在数组里了

}

if(isInArrays==false){

//如果number不在数组randomNumber中

randomNumber[index] = number;

index++;

}

}

return randomNumber;

}

}

范例：JDBC多条件查询

package com.hsp;

import java.sql.*;

public class JdbcMysql {

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

// TODO Auto-generated method stub

Connection con = null;

Statement sql = null;

ResultSet rs = null;

con = GetDBConnection.ConnectDB("jdb", "root", "root");

String query = "SELECT * FROM STUDENTS";

String c1 = " year(birthday)<=2000 and month(birthday)>7";//查询条件1

String c2 = " name Like 'z_%'";//查询条件2

String c3 = " height >1.65";//查询条件3

String sqlStr = "SELECT * FROM students where "+c1+" and "+c2+" and "+c3+" order by birthday";

if(con==null){

System.out.println("连接错误");

return ;

}

try {

sql = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);

rs = sql.executeQuery(sqlStr);

while(rs.next()){

String number = rs.getString(1);

String name = rs.getString(2);

Date date = rs.getDate(3);

float height = rs.getFloat(4);

System.out.println("number:"+number+" name:"+name+" date:"+date+" height:"+height);

}

con.close();

} catch (Exception e) {

// TODO: handle exception

System.out.println(e);

}

}

}

package com.hsp;

import java.sql.Connection;

import java.sql.DriverManager;

public class GetDBConnection {

public static Connection ConnectDB(String DBname,String username,String password) {

Connection con = null;

String url = "jdbc:mysql://localhost:3306/"+DBname+"?useSSL=true&characterEncoding=utf-8";

try {

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

con = DriverManager.getConnection(url, username, password);

} catch (Exception e) {

// TODO: handle exception

System.out.println(e);

}

return con;

}

}

范例：JDBC插入数据

package com.hsp;

import java.sql.*;

public class JdbcMysql {

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

// TODO Auto-generated method stub

Connection con = null;

Statement sql = null;

ResultSet rs = null;

con = GetDBConnection.ConnectDB("jdb", "root", "root");

String query = "SELECT * FROM STUDENTS";

String jilu = "('R1011','JS','2000-10-23',1.66),"+

"('R1010','LW','1989-7-22',1.76)";

String sqlStr = "insert into students values"+jilu;

if(con==null){

System.out.println("连接错误");

return ;

}

try {

sql = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);

int ok = sql.executeUpdate(sqlStr);

rs = sql.executeQuery("select * from students");

while(rs.next()){

String number = rs.getString(1);

String name = rs.getString(2);

Date date = rs.getDate(3);

float height = rs.getFloat(4);

System.out.println("number:"+number+" name:"+name+" date:"+date+" height:"+height);

}

con.close();

} catch (Exception e) {

// TODO: handle exception

System.out.println(e);

}

}

}

package com.hsp;

import java.sql.Connection;

import java.sql.DriverManager;

public class GetDBConnection {

public static Connection ConnectDB(String DBname,String username,String password) {

Connection con = null;

String url = "jdbc:mysql://localhost:3306/"+DBname+"?useSSL=true&characterEncoding=utf-8";

try {

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

con = DriverManager.getConnection(url, username, password);

} catch (Exception e) {

// TODO: handle exception

System.out.println(e);

}

return con;

}

}