MyBatis使用mapper动态代理实现DAO接口 _动态代理

眼前多少难甘事，自古男儿当自强。这篇文章主要讲述MyBatis使用mapper动态代理实现DAO接口相关的知识，希望能为你提供帮助。
【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：

文章图片

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="https://www.songbingjia.com/android/${mysql.driver}" /> < property name="url" value="https://www.songbingjia.com/android/${mysql.url}" /> < property name="username" value="https://www.songbingjia.com/android/${mysql.uid}" /> < property name="password" value="https://www.songbingjia.com/android/${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

1 package com.admin.entities; 2 3 import java.io.Serializable; 4 5 public class Goods implements Serializable { 6 7private static final long serialVersionUID = 1L; 8 9private int id; 10 11private String name; 12 13 14private double price; 15 16private String picture; 17 18public int getId() { 19return id; 20} 21 22public void setId(int id) { 23this.id = id; 24} 25 26public String getName() { 27return name; 28} 29 30public void setName(String name) { 31this.name = name; 32} 33 34public double getPrice() { 35return price; 36} 37 38public void setPrice(double price) { 39this.price = price; 40} 41 42public String getPicture() { 43return picture; 44} 45 46public void setPicture(String picture) { 47this.picture = picture; 48} 49 50@Override 51public String toString() { 52return "Goods{" + 53"id=" + id + 54", name=\'" + name + \'\\\'\' + 55", price=" + price + 56", picture=\'" + picture + \'\\\'\' + 57\'}\'; 58} 59 }

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

1 package com.admin.mapper; 2 3 4 import com.admin.entities.Goods; 5 import org.apache.ibatis.annotations.Param; 6 7 import java.util.List; 8 9 public interface GoodsDAO { 10 11public List< Goods> getGoodsPager(@Param("skip")int skip, @Param("size") int size); 12 13public Goods getGoodsById(int id); 14 15public int getGoodsCount(); 16 17public int insert(Goods entity); 18 19public int delete(int id); 20 21public int update(Goods entity); 22 }

GoodsMapper.xml

1 < ?xml version="1.0" encoding="UTF-8"?> 2 < !DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 3 < !--命名空间应该是对应接口的包名+接口名 --> 4 < mapper namespace="com.admin.mapper.GoodsDAO"> 5< !--获得商品信息并分页 --> 6< select id="getGoodsPager" resultType="Goods"> 7select 8id,name,price,picture from goods limit #{skip},#{size} 9< /select> 10< !-- 获得单个商品通过编号 --> 11< select id="getGoodsById" parameterType="int" resultType="Goods"> 12select 13id,name,price,picture from goods where id=#{id} 14< /select> 15< !--获得商品总数 --> 16< select id="getGoodsCount" resultType="int"> 17select count(*) from goods 18< /select> 19< !--新增加商品 --> 20< insert id="insert" parameterType="Goods"> 21insert into 22goods(name,price,picture) values(#{name},#{price},#{picture}); 23< /insert> 24< !-- 删除商品 --> 25< delete id="delete"> 26delete from goods where id=#{id} 27< /delete> 28< !-- 修改商品 --> 29< update id="update" parameterType="Goods"> 30update goods set 31name=#{name},price=#{price},picture=#{picture} where id=#{id} 32< /update> 33 < /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

1 package test; 2 3 import org.apache.ibatis.session.SqlSession; 4 import org.apache.ibatis.session.SqlSessionFactory; 5 import org.apache.ibatis.session.SqlSessionFactoryBuilder; 6 7 import java.io.InputStream; 8 9 public abstract class MyBatisUtil { 10 11public static SqlSessionFactory getSqlSessionFactory(){ 12// 获得环境配置文件流 13InputStream config = MyBatisUtil.class.getClassLoader().getResourceAsStream("MyBatisCfg.xml"); 14// 创建sql会话工厂 15SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(config); 16return factory; 17} 18 19//获得会话 20public static SqlSession getSession(){ 21return getSqlSessionFactory().openSession(true); 22} 23 24/** 25* 获得得sql会话 26* @param isAutoCommit 是否自动提交，如果为false则需要sqlSession.commit(); rollback(); 27* @return sql会话 28*/ 29public static SqlSession getSession(boolean isAutoCommit){ 30return getSqlSessionFactory().openSession(isAutoCommit); 31} 32 33 }

TestGoods.java

1 package test; 2 3 import com.admin.entities.Goods; 4 import com.admin.mapper.GoodsDAO; 5 import org.apache.ibatis.session.SqlSession; 6 import org.junit.Assert; 7 import org.junit.Test; 8 9 import java.util.List; 10 11 public class TestGoods { 12 13@Test 14public void getGoodsPagerTest() { 15int skip = 4; 16int size = 2; 17SqlSession session = MyBatisUtil.getSession(); 18try { 19GoodsDAO bookdao = session.getMapper(GoodsDAO.class); 20List< Goods> goods = bookdao.getGoodsPager(skip, size); 21Assert.assertEquals(2, goods.size()); 22} finally { 23session.close(); 24} 25} 26 27@Test 28public void getGoodsByIdTest() { 29SqlSession session = MyBatisUtil.getSession(); 30try { 31GoodsDAO bookdao = session.getMapper(GoodsDAO.class); 32Goods goods = bookdao.getGoodsById(1); 33Assert.assertEquals(1, goods.getId()); 34} finally { 35session.close(); 36} 37} 38 39@Test 40public void getGoodsCountTest() { 41SqlSession session = MyBatisUtil.getSession(); 42try { 43GoodsDAO bookdao = session.getMapper(GoodsDAO.class); 44Assert.assertEquals(9, bookdao.getGoodsCount()); 45} finally { 46session.close(); 47} 48} 49 50@Test 51public void insertTest() { 52SqlSession session = MyBatisUtil.getSession(); 53try { 54Goods entity = new Goods(); 55entity.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"); 56entity.setPrice(108); 57entity.setPicture("nopic.jpg"); 58GoodsDAO bookdao = session.getMapper(GoodsDAO.class); 59Assert.assertEquals(1, bookdao.insert(entity)); 60} finally { 61session.close(); 62} 63} 64 65@Test 66public void deleteTest() { 67SqlSession session = MyBatisUtil.getSession(); 68try { 69GoodsDAO bookdao = session.getMapper(GoodsDAO.class); 70Assert.assertEquals(1, bookdao.delete(12)); 71} finally { 72session.close(); 73} 74} 75 76@Test 77public void update() { 78SqlSession session = MyBatisUtil.getSession(); 79try { 80GoodsDAO bookdao = session.getMapper(GoodsDAO.class); 81Goods entity = bookdao.getGoodsById(12); 82entity.setName("正宗无锡阳山水蜜桃新鲜水果水密桃12个6斤装"); 83entity.setPrice(107); 84entity.setPicture("nopicture.jpg"); 85 86Assert.assertEquals(1, bookdao.update(entity)); 87} finally { 88session.close(); 89} 90} 91 }

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 TransferSource Server: localhost Source Server Version : 50536 Source Host: localhost:3306 Source Database: db1Target Server Type: MYSQL Target Server Version : 50536 File Encoding: 65001Date: 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