import java.sql.*;public class CRUD {	public static void main(String[] args) throws SQLException {		select();		System.out.println("-------------------------");		insert();		select();		System.out.println("-------------------------");		delete();		select();		System.out.println("-------------------------");		update();		select();		System.out.println("-------------------------");	}	public static void select() throws SQLException {		Connection connection = null;		PreparedStatement preparedStatement = null;		ResultSet resultSet = null;		DBUtil dbUtils = new DBUtil();		try {			connection = dbUtils.getConnection();			String sql = "select * from studentinfo";			preparedStatement = connection.prepareStatement(sql);			resultSet = preparedStatement.executeQuery();			// System.out.println("=================");			while (resultSet.next()) {				System.out.println(resultSet.getInt("student_id") + "   " + resultSet.getString("student_name"));			}			// dbUtils.closeDBResouse(connection, preparedStatement, resultSet);		} catch (Exception e) {			// TODO: handle exception			e.printStackTrace();		}	}	public static void insert() {		DBUtil dbUtil = new DBUtil();		Connection conn = null;		PreparedStatement stmt = null;		ResultSet rs = null;		try {			conn = dbUtil.getConnection();			String sql = "insert into studentinfo (student_id,student_name,student_pwd) values (1,'wwwwww','1233')";			stmt = conn.prepareStatement(sql);			int count = stmt.executeUpdate(sql);			System.out.println("插入了" + count + "条语句");		} catch (SQLException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}	}	public static void delete() {		DBUtil dbUtil = new DBUtil();		Connection conn = null;		PreparedStatement stmt = null;		ResultSet rs = null;		try {			conn = dbUtil.getConnection();			String sql = "delete from studentinfo where student_id = 1";			stmt = conn.prepareStatement(sql);			int count = stmt.executeUpdate(sql);			System.out.println("您删除了" + count + "条语句");		} catch (SQLException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}	}	public static void update() {		DBUtil dbUtil = new DBUtil();		Connection conn = null;		PreparedStatement stmt = null;		ResultSet rs = null;		try {			conn = dbUtil.getConnection();			String sql = "update studentinfo set student_name='sakura' where student_id = 5";			stmt = conn.prepareStatement(sql);			int count = stmt.executeUpdate(sql);			System.out.println("您修改了" + count + "条语句");		} catch (SQLException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}	}}

　　

import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class DBUtil {    static Connection conn = null;	static Statement stmt = null;	static ResultSet rs= null;	static String url ="jdbc:mysql://localhost:3306/tyzx1?useUnicode=true&characterEncoding=UTF-8";		public Connection getConnection(){		try {			Class.forName("com.mysql.jdbc.Driver");			conn = DriverManager.getConnection(url,"root","2013005488");			System.out.println("success");		} catch (ClassNotFoundException e) {			// TODO Auto-generated catch block			e.printStackTrace();		} catch (SQLException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}		return conn;			}}