》#千锋逆战#

lombok介绍

lombok可以通过简单的注解的形式来帮助我们简化和消除一些必须有但显得很臃肿的Java代码，比如常见的Getter&Setter、toString()、构造函数等等。lombok不仅方便编写，同时也让我们的代码更简洁。
lombok提供了一个功能完整的jar包，可以很方便的与我们的项目进行集成。
详细介绍：https://blog.csdn.net/qq3399013670/article/details/81948737?depth_1-utm_source=distribute.pc_relevant.none-task&utm_source=distribute.pc_relevant.none-task

配置pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.qfedu</groupId>
    <artifactId>MyBatis4</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <!-- 帮助我们快速生成getter and setter、构造器、toString等方法 -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.8</version>
            <scope>provided</scope>
        </dependency>

    </dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>
</project>

在配置mybatis.xml时一定要指定配置文件

<!--指定映射配置文件位置，映射配置文件指的是每一个dao独立的配置文件-->
    <mappers>
        <mapper resource="com/qfedu/mapper/UserMapper.xml"/>
   
    </mappers>

SessionUtils.java

package com.qfedu.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;

public class SessionUtils {

    private static SqlSessionFactory factory=null;
    private static SqlSession session=null;

    static {
        try {
            factory=new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis.xml"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取Session对象
     * @return
     */
    public static SqlSession getSession(){
        session=factory.openSession(true);
        return session;
    }

    /**
     * 关闭Session
     * @param session
     */
    public static void closeSession(SqlSession session){
        session.close();
    }
}

IUserDao.java

package com.qfedu.dao;

import com.qfedu.pojo.User;

import java.util.List;

public interface IUserDao {

    List<User> getAllUser();

    int saveUser(User user);

    int updateUser(User u);

    int deleteUser(int id);
}

UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.qfedu.dao.IUserDao">
    <!--实现mybatis的方式为：接口+xml方式
    这种方式有特别的要求
    1.  namespace必须是接口的全路径
    2.  每个节点的id必须是接口中的方法名
    3.  该接口中的方法不允许重载，否则namespace+id将不唯一
    4.  注意该接口中的增删改的方法的返回值，最好使用int-->
    <select id="getAllUser" resultType="User">
        select * from user
    </select>

    <insert id="saveUser">
        insert into user values (null ,#{username},#{password},#{age},#{sex},#{address})
    </insert>

    <update id="updateUser">
        update user set username=#{username},password=#{password},age=#{age},sex=#{sex},address=#{address} where id=8
    </update>
    <delete id="deleteUser">
        delete from user where id=#{id}
    </delete>
</mapper>

Test.java

package com.qfedu.test;

import com.qfedu.dao.IUserDao;
import com.qfedu.pojo.User;
import com.qfedu.utils.SessionUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.text.DateFormat;
import java.util.List;

public class TestUser2 {

    private SqlSession session = null;

    @Before
    public void setUp() {
        session = SessionUtils.getSession();
    }

    @After
    public void tearDown() {
        SessionUtils.closeSession(session);
    }

    @Test
    public void testU() {
        IUserDao mapper = session.getMapper(IUserDao.class);
        List<User> allUser = mapper.getAllUser();
        for (User user : allUser) {
            System.out.println(user);
        }
    }

    @Test
    public void testSaveUser() {
        IUserDao mapper = session.getMapper(IUserDao.class);
        User u = new User();
        u.setSex("男");
        //u.setBirthday(Timestamp.valueOf(simpleDate.format(nowdate)));
        u.setAddress("江苏");
        u.setUsername("李");
        u.setAge(19);
        u.setPassword("123456");
        int user = mapper.saveUser(u);
        System.out.println(user);

    }
    @Test
    public void testUpdateUser(){
        IUserDao mapper = session.getMapper(IUserDao.class);
        User u=new User();
        u.setSex("男");
        //u.setBirthday(Timestamp.valueOf(simpleDate.format(nowdate)));
        u.setAddress("江苏镇江");
        u.setUsername("yanshixian");
        u.setAge(19);
        u.setPassword("123");
        int user = mapper.updateUser(u);
        System.out.println(user);
    }
    @Test
    public void testDeleteUser(){
        IUserDao mapper = session.getMapper(IUserDao.class);
        int user = mapper.deleteUser(3);
        System.out.println(user);
    }

}