JDBC连接MySql数据库的简单例子

本blog提供了一个简单JDBC连接数据库的例子，并分别通过Statement和PreparedStatement实现对数据库的查询。

一、为项目添加数据库驱动，本文以MySQL为例

   1）创建一个Java项目（Java Project）,并在项目中建立一个lib文件夹，将下载的mysql驱动复制到该目录下，右
键mysql驱动qu驱动包->BuildPath->Add To Build Path;添加成功！


 2）建立数据库ygw_test,执行以下sql语句，创建user表，并添加测试数据



3）创建属性文件(db.properties)，配置数据库的连接信息

     注意：db.properties必须放在项目的根目录

#mysql DB properties
driver_class=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/ygw_test
username=chaoyue
password=chaoyue

4）建立jdbc连接

package com.chaoyue.jdbc.util;

import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

/**
* 该类封装了连接和关闭数据库连接操作
*
* @author 超越
* @Date 2016年11月30日,下午3:10:10
* @motto 人在一起叫聚会，心在一起叫团队
* @Version 1.0
*/
public class DBUtil {
public static Connection getConnection() {
Properties prop = new Properties();
FileInputStream fis = null;
Connection con = null;
try {
fis = new FileInputStream("db.properties");
prop.load(fis);
// 加载驱动
Class.forName(prop.getProperty("driver_class"));
// 建立连接
con = DriverManager.getConnection(prop.getProperty("url"), prop.getProperty("username"), prop.getProperty("password"));
} catch (Exception e) {
e.printStackTrace();
}
return con;
}

// 关闭ResultSet
public static void closeResultSet(ResultSet rs) {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}

// 关闭PreparedStatement
public static void closePreparedStatement(PreparedStatement pstm) {
if (pstm != null) {
try {
pstm.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
// 关闭Statement
public static void closeStatement(Statement stmt) {
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
// 关闭Connection
public static void closeConnection(Connection con) {
if (con != null) {
try {
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}

5） 使用Statement和PreparedStatement查询数据

package com.chaoyue.jdbc.test;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import com.chaoyue.jdbc.model.User;
import com.chaoyue.jdbc.util.DBUtil;
/**
* 使用statement进行查询
* @author 超越
* @Date 2016年11月30日,下午3:29:32
* @motto 人在一起叫聚会，心在一起叫团队
* @Version 1.0
*/
public class QueryAllUser {
// 使用statement进行查询
public static void queryAllByStatement() {
List<User> userList = new ArrayList<User>();
// 获得连接
Connection con = DBUtil.getConnection();
Statement stmt = null;
ResultSet rs = null;
try {
stmt = con.createStatement();
rs = stmt.executeQuery("select * from user");
while (rs.next()) {
User user = new User();
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
user.setGender(rs.getString("gender"));
user.setRegtime(rs.getDate("regtime"));
System.out.println(user.toString());
userList.add(user);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.closeResultSet(rs);
DBUtil.closeStatement(stmt);
DBUtil.closeConnection(con);
}
}

// 通过id查询用户
public static void queryAllById(int id) {
Connection con = DBUtil.getConnection();
Statement stmt = null;
ResultSet rs = null;
try {
stmt = con.createStatement();
rs = stmt.executeQuery("select * from  user where id =" + id);
while (rs.next()) {
User user = new User();
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
user.setGender(rs.getString("gender"));
user.setRegtime(rs.getDate("regtime"));
System.out.println(user.toString());
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.closeResultSet(rs);
DBUtil.closeStatement(stmt);
DBUtil.closeConnection(con);
}
}

// 使用PreparedStatement进行查询
public static void queryAllByPreparedStatement() {
List<User> userList = new ArrayList<User>();
Connection con = DBUtil.getConnection();
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = con.prepareStatement("select * from user");
rs = ps.executeQuery();
while (rs.next()) {
User user = new User();
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
user.setGender(rs.getString("gender"));
user.setRegtime(rs.getDate("regtime"));
System.out.println(user.toString());
userList.add(user);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.closeResultSet(rs);
DBUtil.closeStatement(ps);
DBUtil.closeConnection(con);
}
}

public static void queryPreparedById(int id) {
Connection con = DBUtil.getConnection();
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = con.prepareStatement("select * from  user where id=?");
ps.setInt(1, id);
rs = ps.executeQuery();
while (rs.next()) {
User user = new User();
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
user.setGender(rs.getString("gender"));
user.setRegtime(rs.getDate("regtime"));
System.out.println(user.toString());
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.closeResultSet(rs);
DBUtil.closeStatement(ps);
DBUtil.closeConnection(con);
}
}
}

6) 测试用例