JavaEE学习之jdbc基础认识

JDBC的定义：

　　Java Data Base Connectivity,java数据库连接；是一种用于执行SQL语句的Java API;

JDBC的操作步骤：

　　1.注册驱动

Class.forName();

　　2.获取连接

Connection xxx=DriverManager.getConnection();

　　3.编写sql

String sql=“ ”；

　　4.创建预编译的语句执行者

prepareStatement yyy=xxx.prepareStatement(sql,username,password);

　　5.设置参数

yyy.getString ()或者yyy.getInt();

　　6.执行查询

查询操作

yyy.executeQuery();

增删改操作

yyy.executeUpdate();

　　7.释放资源

？？？.close();

 案例：

package cn.it.jdbc;

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 org.junit.Test;

import com.jdbc.utlis.jdbcUtils;
import com.jdbc.utlis.jdbcUtilsDemo;

public class helloDemo {
    @Test
    public void Myjdbc() throws ClassNotFoundException, SQLException {
        // 1.注册驱动
        Class.forName("com.mysql.jdbc.Driver");
        // 2.获取连接
        Connection connection = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306/day01", "root", "root");
        // 3.编写sql
        String sql = "select * from user";
        // 4.创建语句执行者
        PreparedStatement statement = connection.prepareStatement(sql);
        // 5.设置参数

        // 6.执行sql语句
        ResultSet resultSet = statement.executeQuery();
        // 7.遍历结果
        while (resultSet.next()) {
            System.out.println(resultSet.getString("id") + "----"
                    + resultSet.getString("username"));

        }
        resultSet.close();
        statement.close();
        connection.close();
    }

    // 测试jdbcUtils测试方法
    @Test
    public void Utils() {
        Connection connection = null;
        PreparedStatement statement = null;

        // 获取连接
        try {
            connection = jdbcUtils.getConnection();
            // 编写SQL语句
            String sql = "INSERT INTO user VALUES(?,?)";
            // 语句预编译
            statement = connection.prepareStatement(sql);
            // 设置参数
            statement.setInt(1, 5);
            statement.setString(2, "小明");
            // 执行SQL
            int i = statement.executeUpdate();
            // 判断语句是否执行成功
            if (i == 1) {
                System.out.println("OK!!!");
            } else {
                System.out.println("NO!!!");
            }

        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            jdbcUtils.closeStatent(statement);
            jdbcUtils.closeConn(connection);

        }

    }

    // 更新操作
    @Test
    public void update() {
        Connection connection = null;
        PreparedStatement statement = null;
        try {
            // 注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            // 获取连接
            connection = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/day01", "root", "root");
            // sq1语句
            String sql = " UPDATE user SET username=? where id=? ";
            // 创建语句执行者
            statement = connection.prepareStatement(sql);
            // 设置参数
            statement.setString(1, "尔康");
            statement.setInt(2, 6);
            // 执行sql语句
            statement.executeUpdate();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        try {
            statement.close();
            connection.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    // 删除操作
    @Test
    public void delete() {
        Connection connection = null;
        PreparedStatement prepareStatement = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/day01", "root", "root");
            String sql = "delete from user where id=?";
            prepareStatement = connection.prepareStatement(sql);
            prepareStatement.setInt(1, 5);
            int i = prepareStatement.executeUpdate();
            if (i == 1) {
                System.out.println("OK");
            }
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        try {
            prepareStatement.close();
            connection.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}