SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for student
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student`  (
  `id` int(11) NOT NULL,
  `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
  `sex` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

SET FOREIGN_KEY_CHECKS = 1;

package JDBC温习;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * 提供获取连接和释放资源的 方法
 */
public class JDBCUtils {

    /*
     * 获取连接方法
     */
    public static Connection getConnection() {
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3307/test", "root", "123456");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }
    /*
     * 释放资源
     */
    public static void release(Connection conn, PreparedStatement pstmt, ResultSet rs) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (pstmt != null) {
            try {
                pstmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
}

package JDBC温习;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import org.junit.Test;

/*
 * 测试类
 */
public class test {
    /*
     * 添加用户
     */
    @Test
    public void add() {
        Connection conn = null;
        PreparedStatement pst = null;

        try {
            // 1.获取连接
            conn = (Connection) JDBCUtils.getConnection();
            // 2.编写sql语句(采用PreparedStatement)
            String sql = "insert into student values(?,?,?) ";
            // 3.获取执行sql语句的载体
            pst = conn.prepareStatement(sql);
            // 4.设置占位符
            pst.setInt(1, 6);
            pst.setString(2, "周东");
            pst.setString(3, "男");
            // 5.执行插入操作
            int updateRow = pst.executeUpdate();
            if (updateRow > 0) {
                System.out.println("插入成功");
            } else {
                System.out.println("插入失败");
            }

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            JDBCUtils.release(conn, pst, null);
        }
    }

    /*
     * 删除用户
     */
    @Test
    public void deleteById() {
        Connection conn = null;
        Statement stmt = null;
        try {
            // 1. 获取连接
            conn = JDBCUtils.getConnection();
            // 2. 编写sql语句(采用Statement方式)
            String sql = "delete from student where id=2 ";
            // 3. 获取sql语句载体
            stmt = conn.createStatement();
            // 4. 执行sql语句
            int updateRow = stmt.executeUpdate(sql);
            if (updateRow > 0) {
                System.out.println("删除成功");
            } else {
                System.out.println("删除失败");
            }
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        } finally {
            // 这里因为我工具类提供的是preparedStatement的关闭.
            JDBCUtils.release(conn, null, null);
        }
    }

    /*
     * 修改用户
     */
    @Test
    public void updateById() {
        Connection conn = null;
        PreparedStatement pst = null;
        try {
            // 1. 获取连接
            conn = JDBCUtils.getConnection();
            // 2. 编写sql语句(PreparedStatement方式)
            String sql = "update student set name=? , sex=? where id=? ";
            // 3. 创建sql载体
            pst = conn.prepareStatement(sql);
            // 4. 设置占位符
            pst.setString(1, "小花");
            pst.setString(2, "女");
            pst.setInt(3, 4);
            // 5. 执行sql语句
            int updateRow = pst.executeUpdate();
            if (updateRow > 0) {
                System.out.println("更新成功");
            } else {
                System.out.println("更新失败");
            }
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        } finally {
            JDBCUtils.release(conn, pst, null);
        }
    }

    /*
     * 查询用户 PS:简单查询，根据ID查某个学生
     */
    @Test
    public void findById() {
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {
            // 1. 获取连接
            conn = JDBCUtils.getConnection();
            // 2.编写sql语句
            String sql = "select * from student where id = 6 ";
            // 3.编写sql载体
            stmt = conn.createStatement();
            //4.执行sql语句
            rs = stmt.executeQuery(sql);
            //5. 遍历
            while(rs.next()) {
                System.out.println(rs.getString(2)+"====="+rs.getString("sex"));
            }
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }finally {
            JDBCUtils.release(conn, null, rs);
        }
    }
}