JDBC连接MySQL数据库查询数据

首先，创建chapter01数据库并创建users表插入数据。

users表数据如下：

其次，新建Java类，该类用于读取数据库中的表，并将结果输出。

操作如下：

• 1.注册数据库的驱动。

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

注意：此时代码会报错，需用try catch包围。

• 2.通过DriverManager获取数据库连接

	String url = "jdbc:mysql://localhost:3306/chapter01?useSSL=false&serverTimezone=UTC";
	String username = "root";
	String password = "123456";
	Connection conn = DriverManager.getConnection(url, username, password);

• 3.通过Connection对象获取Statement对象

	Statement stmt = conn.createStatement();

• 4.使用Statement执行SQL语句

	String sql = "select * from users";
	ResultSet rs = stmt.executeQuery(sql);

• 5.操作ResultSet结果集

	System.out.println("id|name|password|email|birthday");
	while (rs.next()){
		int id = rs.getInt("id");
		String name = rs.getString("name");
		String psw = rs.getString("password");
		String email = rs.getString("email");
		Date birthday = rs.getDate("birthday");
		System.out.println(id+"|"+name+"|"+psw+"|"+email+"|"+birthday);
	}

• 6.回收数据库资源

	if (rs!=null){
		try {
				rs.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
			rs=null;
		}
		if(stmt!=null){
			try {
				stmt.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
			stmt=null;
		}
		if(conn!=null){
			try {
				conn.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
			conn=null;
		}

注意：回收数据库资源需在finally下进行

• 7.运行结果为：
  

完整代码如下：

package cn.itcast.jdbc.example;

import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class Example01 {
	public static void main(String[] args) throws SQLException {
		Connection conn = null;
		Statement stmt = null;
		ResultSet rs = null;

		try {
			//1.注册数据库的驱动
			Class.forName("com.mysql.cj.jdbc.Driver");
			//2.通过DriverManager获取数据库连接
			String url = "jdbc:mysql://localhost:3306/chapter01?useSSL=false&serverTimezone=UTC";
			String username = "root";
			String password = "123456";
			conn = DriverManager.getConnection(url, username, password);
			//3.通过Connection对象获取Statement对象
			stmt = conn.createStatement();
			//4.使用Statement执行SQL语句
			String sql = "select * from users";
			rs = stmt.executeQuery(sql);
			//5.操作ResultSet结果集
			System.out.println("id|name|password|email|birthday");
			while (rs.next()){
				int id = rs.getInt("id");
				String name = rs.getString("name");
				String psw = rs.getString("password");
				String email = rs.getString("email");
				Date birthday = rs.getDate("birthday");
				System.out.println(id+"|"+name+"|"+psw+"|"+email+"|"+birthday);
			}
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			//6.回收数据库资源
			if (rs!=null){
				try {
					rs.close();
				} catch (Exception e) {
					e.printStackTrace();
				}
				rs=null;
			}
			if(stmt!=null){
				try {
					stmt.close();
				} catch (Exception e) {
					e.printStackTrace();
				}
				stmt=null;
			}
			if(conn!=null){
				try {
					conn.close();
				} catch (Exception e) {
					e.printStackTrace();
				}
				conn=null;
			}
		}
	}
}