上篇博文的基于xml配置的只要学会了，原理搞清楚了，那么注解的方式更是随意学会，因为注解就是为了简化配置，甚至是不需要xml文件配置的。
下面是装载别人的一个注解项目，可以参考改动：
1、定义sql映射的接口
package me.gacl.mapping;
import java.util.List;
import me.gacl.domain.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
/**
* @author gacl
* 定义sql映射的接口，使用注解指明方法要执行的SQL
*/
public interface UserMapperI {
//使用@Insert注解指明add方法要执行的SQL
@Insert("insert into users(name, age) values(#{name}, #{age})")
public int add(User user);
//使用@Delete注解指明deleteById方法要执行的SQL
@Delete("delete from users where id=#{id}")
public int deleteById(int id);
//使用@Update注解指明update方法要执行的SQL
@Update("update users set name=#{name},age=#{age} where id=#{id}")
public int update(User user);
//使用@Select注解指明getById方法要执行的SQL
@Select("select * from users where id=#{id}")
public User getById(int id);
//使用@Select注解指明getAll方法要执行的SQL
@Select("select * from users")
public List<User> getAll();
}
2、在 conf.xml文件注册映射接口
<?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>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<!-- 配置数据库连接信息 -->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/mybatis" />
<property name="username" value="root" />
<property name="password" value="XDP" />
</dataSource>
</environment>
</environments>
<mappers>
<!-- 注册userMapper.xml文件，
userMapper.xml位于me.gacl.mapping这个包下，所以resource写成me/gacl/mapping/userMapper.xml-->
<mapper resource="me/gacl/mapping/userMapper.xml"/>
<!-- 注册UserMapper映射接口-->
<mapper class="me.gacl.mapping.UserMapperI"/>
</mappers>
</configuration>
3.测试类方法：
package me.gacl.test;
import java.util.List;
import me.gacl.domain.User;
import me.gacl.mapping.UserMapperI;
import me.gacl.util.MyBatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
public class TestCRUDByAnnotationMapper {
@Test
public void testAdd(){
SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
//得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
User user = new User();
user.setName("用户xdp");
user.setAge(20);
int add = mapper.add(user);
//使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(add);
}
@Test
public void testUpdate(){
SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
//得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
User user = new User();
user.setId(3);
user.setName("孤傲苍狼_xdp");
user.setAge(26);
//执行修改操作
int retResult = mapper.update(user);
//使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(retResult);
}
@Test
public void testDelete(){
SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
//得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
//执行删除操作
int retResult = mapper.deleteById(7);
//使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(retResult);
}
@Test
public void testGetUser(){
SqlSession sqlSession = MyBatisUtil.getSqlSession();
//得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
//执行查询操作，将查询结果自动封装成User返回
User user = mapper.getById(8);
//使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(user);
}
@Test
public void testGetAll(){
SqlSession sqlSession = MyBatisUtil.getSqlSession();
//得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
//执行查询操作，将查询结果自动封装成List<User>返回
List<User> lstUsers = mapper.getAll();
//使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(lstUsers);
}
}
4.一个原作者封装的MyBatisUtil工具类：
package me.gacl.util;
import java.io.InputStream;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class MyBatisUtil {
/**
* 获取SqlSessionFactory
* @return SqlSessionFactory
*/
public static SqlSessionFactory getSqlSessionFactory() {
String resource = "conf.xml";
InputStream is = MyBatisUtil.class.getClassLoader().getResourceAsStream(resource);
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
return factory;
}
/**
* 获取SqlSession
* @return SqlSession
*/
public static SqlSession getSqlSession() {
return getSqlSessionFactory().openSession();
}
/**
* 获取SqlSession
* @param isAutoCommit
* true 表示创建的SqlSession对象在执行完SQL之后会自动提交事务
* false 表示创建的SqlSession对象在执行完SQL之后不会自动提交事务，这时就需要我们手动调用sqlSession.commit()提交事务
* @return SqlSession
*/
public static SqlSession getSqlSession(boolean isAutoCommit) {
return getSqlSessionFactory().openSession(isAutoCommit);
}
}