MyBatis使用mapper动态代理实现DAO接口

工具： mysql 5.5.62   IDEA

参考自：https://www.cnblogs.com/best/p/5688040.html

遇到的问题： 无法读取src/main/java下配置文件， 解决方法参考自https://blog.csdn.net/qq_32778043/article/details/80746668

项目目录如下：

1   创建maven项目，添加jar包

首先不使用模板创建一个maven项目，groupid填com.admin,  artifactid为MybatisTest，添加jar包，修改pom.xml为：

<?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.admin</groupId>
    <artifactId>MybatisTest</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <!-- mybatis ORM框架 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.1</version>
        </dependency>
        <!--mysql数据库驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.12</version>
        </dependency>
        <!-- JUnit单元测试工具 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>

    </dependencies>

    <!--解决IDEA无法读取src/main/java/配置文件问题-->
    <build>
        <finalName>MybatisTest</finalName>
        <resources>
            <resource>
                <directory>${basedir}/src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
            </resource>
            <resource>
                <directory>${basedir}/src/main/resources</directory>
            </resource>
        </resources>
    </build>

</project>

2   添加mybatis配置文件

在src/main/java包下添加mybatis配置文件MyBatisCfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!--引入类路径下的资源-->
    <properties resource="db.properties"></properties>
    <typeAliases>
        <package name="com.admin.entities" />
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${mysql.driver}" />
                <property name="url" value="${mysql.url}" />
                <property name="username" value="${mysql.uid}" />
                <property name="password" value="${mysql.password}" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/admin/mapper/GoodsMapper.xml" />
    </mappers>
</configuration>

在src/main/java目录下添加数据库配置文件db.properties文件（对应MyBatisCfg.xml中db.peroperties），mysql-connector-java-8.0.12对应driver及url与前面的版本有些差异

mysql.driver=com.mysql.cj.jdbc.Driver
mysql.url=jdbc:mysql://localhost:3306/db1?serverTimezone=GMT%2B8
mysql.uid=root
mysql.password=123456

3   创建DAO接口GoodsDAO及对应的GoodsMapper.xml

在src/main/java下新建com.admin包，其下再新建entities包及mapper包

在com.admin.entities（与MyBatisCfg.xml中package name对应）中创建Goods类Goods.java

 package com.admin.entities;

 import java.io.Serializable;

 public class Goods implements Serializable {

     private static final long serialVersionUID = 1L;

     private int id;

     private String name;

     private double price;

     private String picture;

     public int getId() {
         return id;
     }

     public void setId(int id) {
         this.id = id;
     }

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public double getPrice() {
         return price;
     }

     public void setPrice(double price) {
         this.price = price;
     }

     public String getPicture() {
         return picture;
     }

     public void setPicture(String picture) {
         this.picture = picture;
     }

     @Override
     public String toString() {
         return "Goods{" +
                 "id=" + id +
                 ", name='" + name + '\'' +
                 ", price=" + price +
                 ", picture='" + picture + '\'' +
                 '}';
     }
 }

在com.admin.mapper包下创建GoodsDAO接口及GoodsMapper.xml

GoodsDAO.java

 package com.admin.mapper;

 import com.admin.entities.Goods;
 import org.apache.ibatis.annotations.Param;

 import java.util.List;

 public interface GoodsDAO {

     public List<Goods> getGoodsPager(@Param("skip")int skip, @Param("size") int size);

     public Goods getGoodsById(int id);

     public int getGoodsCount();

     public int insert(Goods entity);

     public int delete(int id);

     public int update(Goods entity);
 }

GoodsMapper.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">
 <!--命名空间应该是对应接口的包名+接口名 -->
 <mapper namespace="com.admin.mapper.GoodsDAO">
     <!--获得商品信息并分页 -->
     <select id="getGoodsPager" resultType="Goods">
         select
         id,name,price,picture from goods limit #{skip},#{size}
     </select>
     <!-- 获得单个商品通过编号 -->
     <select id="getGoodsById" parameterType="int" resultType="Goods">
         select
         id,name,price,picture from goods where id=#{id}
     </select>
     <!--获得商品总数 -->
     <select id="getGoodsCount" resultType="int">
         select count(*) from goods
     </select>
     <!--新增加商品 -->
     <insert id="insert" parameterType="Goods">
         insert into
         goods(name,price,picture) values(#{name},#{price},#{picture});
     </insert>
     <!-- 删除商品 -->
     <delete id="delete">
         delete from goods where id=#{id}
     </delete>
     <!-- 修改商品 -->
     <update id="update" parameterType="Goods">
         update goods set
         name=#{name},price=#{price},picture=#{picture} where id=#{id}
     </update>
 </mapper>

4  创建junit测试类

在src/test/java创建包test，创建两个类MyBatisUtil.java和TestGoods.java

MyBatisUtil.java

 package test;

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

 import java.io.InputStream;

 public abstract class MyBatisUtil {

     public static SqlSessionFactory getSqlSessionFactory(){
         // 获得环境配置文件流
         InputStream config = MyBatisUtil.class.getClassLoader().getResourceAsStream("MyBatisCfg.xml");
         // 创建sql会话工厂
         SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(config);
         return factory;
     }

     //获得会话
     public static SqlSession getSession(){
         return getSqlSessionFactory().openSession(true);
     }

     /**
      * 获得得sql会话
      * @param isAutoCommit 是否自动提交，如果为false则需要sqlSession.commit();rollback();
      * @return sql会话
      */
     public static SqlSession getSession(boolean isAutoCommit){
         return getSqlSessionFactory().openSession(isAutoCommit);
     }

 }

TestGoods.java

 package test;

 import com.admin.entities.Goods;
 import com.admin.mapper.GoodsDAO;
 import org.apache.ibatis.session.SqlSession;
 import org.junit.Assert;
 import org.junit.Test;

 import java.util.List;

 public class TestGoods {

     @Test
     public void getGoodsPagerTest() {
         int skip = 4;
         int size = 2;
         SqlSession session = MyBatisUtil.getSession();
         try {
             GoodsDAO bookdao = session.getMapper(GoodsDAO.class);
             List<Goods> goods = bookdao.getGoodsPager(skip, size);
             Assert.assertEquals(2, goods.size());
         } finally {
             session.close();
         }
     }

     @Test
     public void getGoodsByIdTest() {
         SqlSession session = MyBatisUtil.getSession();
         try {
             GoodsDAO bookdao = session.getMapper(GoodsDAO.class);
             Goods goods = bookdao.getGoodsById(1);
             Assert.assertEquals(1, goods.getId());
         } finally {
             session.close();
         }
     }

     @Test
     public void getGoodsCountTest() {
         SqlSession session = MyBatisUtil.getSession();
         try {
             GoodsDAO bookdao = session.getMapper(GoodsDAO.class);
             Assert.assertEquals(9, bookdao.getGoodsCount());
         } finally {
             session.close();
         }
     }

     @Test
     public void insertTest() {
         SqlSession session = MyBatisUtil.getSession();
         try {
             Goods entity = new Goods();
             entity.setName("正宗无锡阳山水蜜桃新鲜水果水密桃12个6斤装江浙沪皖顺丰包邮");
             entity.setPrice(108);
             entity.setPicture("nopic.jpg");
             GoodsDAO bookdao = session.getMapper(GoodsDAO.class);
             Assert.assertEquals(1, bookdao.insert(entity));
         } finally {
             session.close();
         }
     }

     @Test
     public void deleteTest() {
         SqlSession session = MyBatisUtil.getSession();
         try {
             GoodsDAO bookdao = session.getMapper(GoodsDAO.class);
             Assert.assertEquals(1, bookdao.delete(12));
         } finally {
             session.close();
         }
     }

     @Test
     public void update() {
         SqlSession session = MyBatisUtil.getSession();
         try {
             GoodsDAO bookdao = session.getMapper(GoodsDAO.class);
             Goods entity = bookdao.getGoodsById(12);
             entity.setName("正宗无锡阳山水蜜桃新鲜水果水密桃12个6斤装");
             entity.setPrice(107);
             entity.setPicture("nopicture.jpg");

             Assert.assertEquals(1, bookdao.update(entity));
         } finally {
             session.close();
         }
     }
 }

5  导入SQL并测试

使用navicat等工具， 创建数据库db1，导入sql数据，

/*
Navicat MySQL Data Transfer

Source Server         : localhost
Source Server Version : 50536
Source Host           : localhost:3306
Source Database       : db1

Target Server Type    : MYSQL
Target Server Version : 50536
File Encoding         : 65001

Date: 2016-07-20 10:13:58
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for `goods`
-- ----------------------------
DROP TABLE IF EXISTS `goods`;
CREATE TABLE `goods` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(200) NOT NULL,
  `price` decimal(10,2) DEFAULT '0.00',
  `picture` varchar(100) DEFAULT 'default.jpg',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=12 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of goods
-- ----------------------------
INSERT INTO `goods` VALUES ('1', 'G7 中原G7三合一浓醇咖啡固体饮料1200', '66.50', '1.jpg');
INSERT INTO `goods` VALUES ('2', '百草味东北松子200gx2袋 坚果炒货零', '42.90', '2.jpg');
INSERT INTO `goods` VALUES ('3', '奈津香 桂圆干500gx2袋莆田特产5A桂', '39.90', '3.jpg');
INSERT INTO `goods` VALUES ('4', '益达尊享护齿装草本40粒+冰柠40粒+西', '25.90', '4.jpg');
INSERT INTO `goods` VALUES ('5', '猴坑茶业2016新茶原产地手工太平猴魁特', '168.00', '5.jpg');
INSERT INTO `goods` VALUES ('6', '嘻鱿记 休闲零食 麻辣香辣奶香炭烧 5种', '39.80', '6.jpg');
INSERT INTO `goods` VALUES ('7', '荣业鸿福五分瘦腊肠 香港土特产香肠腊味', '126.80', '7.jpg');
INSERT INTO `goods` VALUES ('8', '蓓琳娜（BELLINA）3L PDO特级初榨橄榄油', '178.00', '8.jpg');
INSERT INTO `goods` VALUES ('10', '荣业鸿福五分瘦腊肠 香港土特产香肠腊味', '30.60', 'b454b44f-868e-4efe-ae17-91e9e6a58390.jpg');

点击TestGoods类中被@Test注解的各方法前的箭头，执行测试