1. 注解方式单表的CRUD的操作

1. SqlMapConfig.xml配置文件

<?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><!-- 单独管理数据库的信息，读取外部配置文件 --><properties resource="jdbc.properties"></properties><settings><!-- 开启延迟加载 --><setting name="lazyLoadingEnabled" value="true"/><!-- 将积极加载改为消极加载及按需加载 --><setting name="aggressiveLazyLoading" value="false"/><!-- 开启二级缓存 --><setting name="cacheEnabled" value="true"/></settings><!-- 注册别名 --><typeAliases><!-- 默认的规范，该包下所有的JavaBean都默认的别名，当前类名做为别名 --><package name="com.qcby.domain"/></typeAliases><!-- 配置环境们 --><environments default="mysql"><!-- 配置具体的环境 --><environment id="mysql"><!-- 配置事务管理，使用JDBC的事务管理 --><transactionManager type="JDBC"/><dataSource type="POOLED"><!-- 具体连接的信息配置上 --><property name="driver" value="${jdbc.driver}"/><property name="url" value="${jdbc.url}"/><property name="username" value="${jdbc.username}"/><property name="password" value="${jdbc.password}"/></dataSource></environment></environments><!-- 引入mapper的配置文件 --><mappers><package name="com.qcby.mapper"/></mappers>
</configuration>  ​

     2.UserMapper接口方法和注解的编写

package com.qcby.mapper;
​
import java.util.List;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.ResultMap;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import com.qcby.domain.User;
​
/*** 在MyBatis环境中，UserDao称为UserMapper接口* @author Administrator*/
public interface UserMapper {@Select(value="select * from user")@Results(id="userMap",value= {@Result(id=true,column="id",property="id"),@Result(column="username",property="username"),@Result(column="birthday",property="birthday"),@Result(column="sex",property="sex"),@Result(column="address",property="address")})public List<User> findAll();@Select(value="select * from user where id = #{uid}")@ResultMap(value="userMap")public User findById(Integer uid);
​// 保存@Insert(value="insert into user (username,birthday,sex,address) values (#{username},#{birthday},#{sex},#{address})")public void insert(User user);// 修改@Update("update user set username = #{username},birthday=#{birthday},sex=#{sex},address=#{address} where id = #{id}")public void update(User user);// 删除@Delete("delete from user where id = #{id}")public void delete(Integer userId);// 查询数量@Select("select count(*) from user")public Integer findByCount();// 模糊查询@Select("select * from user where username like #{username}")public List<User> findByUsername(String username);}​

     3.UserTest测试方法的编写

package com.qcby.test;
import java.io.InputStream;
import java.util.Date;
import java.util.List;
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 org.junit.After;
import org.junit.Before;
import org.junit.Test;
import com.qcby.domain.User;
import com.qcby.mapper.UserMapper;
​
public class UserTest {    private InputStream in;private SqlSession session;SqlSessionFactory factory;private UserMapper mapper;// 初始化的方法@Beforepublic void init() throws Exception {// 加载主配置文件in = Resources.getResourceAsStream("SqlMapConfig.xml");// 创建工厂对象factory = new SqlSessionFactoryBuilder().build(in);// 创建sessionsession = factory.openSession();// 获取到代理对象mapper = session.getMapper(UserMapper.class);}// 销毁的方法@Afterpublic void destory() throws Exception {// 关闭资源session.close();in.close();}/*** 测试查询* @throws Exception*/@Testpublic void testFindAll() throws Exception {// 调用方法List<User> list = mapper.findAll();for (User user : list) {System.out.println(user);}}@Testpublic void testFindById() {User user = mapper.findById(41);System.out.println(user);}/*** 保存* @throws Exception*/@Testpublic void testInsert() throws Exception {// 创建User对象User user = new User();user.setUsername("美美2");user.setBirthday(new Date());user.setSex("女");user.setAddress("监狱");// 保存mapper.insert(user);session.commit();}/*** 测试* @throws Exception*/@Testpublic void testUpdate() throws Exception {// 先通过id查询User user = mapper.findById(41);// 设置新的数据内容user.setUsername("熊大");user.setAddress("深林深处");// 修改mapper.update(user);session.commit();}/*** 删除* @throws Exception*/@Testpublic void testDelete() throws Exception {mapper.delete(2);session.commit();}/*** 查询的是聚合函数* @throws Exception*/@Testpublic void testFindByCount() throws Exception {Integer count = mapper.findByCount();System.out.println("总数量："+count);}/*** 模糊查询* @throws Exception*/@Testpublic void testFindByUsername() throws Exception {// 第一种测试的方式List<User> list = mapper.findByUsername("%王%");for (User user : list) {System.out.println(user);}}
​
}
​​

2. 多对一的注解查询

 1.多对一立即加载查询（推荐）

1. AccountMapper接口编写方法和注解

/*** 立即加载* @return*/@Select("SELECT a.ID AS aid,a.UID,a.MONEY,u.* FROM account a,USER u WHERE a.UID = u.id")@Results(value= {@Result(id=true,column="aid",property="id"),@Result(column="uid",property="uid"),@Result(column="money",property="money"),@Result(column="id",property="user.id"),@Result(column="username",property="user.username"),@Result(column="birthday",property="user.birthday"),@Result(column="sex",property="user.sex"),@Result(column="address",property="user.address")})public List<Account> findAll();

     2.AccountTest进行测试

package com.qcby.test;
import java.io.InputStream;
import java.util.List;
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 org.junit.After;
import org.junit.Before;
import org.junit.Test;
import com.qcby.domain.Account;
import com.qcby.mapper.AccountMapper;
​
public class AccountTest {private InputStream in;private SqlSession session;private AccountMapper mapper;// 初始化的方法@Beforepublic void init() throws Exception {// 加载主配置文件in = Resources.getResourceAsStream("SqlMapConfig.xml");// 创建工厂对象SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);// 创建sessionsession = factory.openSession();// 获取到代理对象mapper = session.getMapper(AccountMapper.class);}// 销毁的方法@Afterpublic void destory() throws Exception {// 关闭资源session.close();in.close();}/*** 测试查询* @throws Exception*/@Testpublic void testFindAll() throws Exception {// 调用方法List<Account> list = mapper.findAll();for (Account account : list) {System.out.println(account);}}
}

 2.多对一延迟加载查询

1. AccountMapper编写方法和注解

/*** 延迟加载* @return*/@Select("select * from account")@Results(value= {@Result(id=true,column="aid",property="id"),@Result(column="uid",property="uid"),@Result(column="money",property="money"),@Result(property="user",javaType=User.class,column="uid",one=@One(select="com.qcby.mapper.UserMapper.findById",fetchType=FetchType.LAZY))})public List<Account> findAll();   

     2.UserMapper接口编写方法

@Select(value="select * from user where id = #{uid}")public User findById(Integer uid);

     3.测试

package com.qcby.test;
import java.io.InputStream;
import java.util.List;
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 org.junit.After;
import org.junit.Before;
import org.junit.Test;
import com.qcby.domain.Account;
import com.qcby.mapper.AccountMapper;
​
public class AccountTest {    private InputStream in;private SqlSession session;private AccountMapper mapper;// 初始化的方法@Beforepublic void init() throws Exception {// 加载主配置文件in = Resources.getResourceAsStream("SqlMapConfig.xml");// 创建工厂对象SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);// 创建sessionsession = factory.openSession();// 获取到代理对象mapper = session.getMapper(AccountMapper.class);}// 销毁的方法@Afterpublic void destory() throws Exception {// 关闭资源session.close();in.close();}/*** 测试查询* @throws Exception*/@Testpublic void testFindAll() throws Exception {// 调用方法List<Account> list = mapper.findAll();for (Account account : list) {System.out.println(account.getMoney());System.out.println(account.getUser());}}}​

3. 一对多的注解查询

        1.一对多查询，使用延迟加载的方式查询

        2.UserMapper接口编写方法

/*** 查询用户，延迟加载用户下的所有的账号* @return*/@Select(value="select * from user")@Results(id="userMap",value= {@Result(id=true,column="id",property="id"),@Result(column="username",property="username"),@Result(column="birthday",property="birthday"),@Result(column="sex",property="sex"),@Result(column="address",property="address"),@Result(property="accounts",column="id",many=@Many(select="com.qcby.mapper.AccountMapper.findByUid",fetchType=FetchType.LAZY))})public List<User> findAll(); 

     3.测试

/*** 测试查询* @throws Exception*/@Testpublic void testFindAll() throws Exception {// 调用方法List<User> list = mapper.findAll();for (User user : list) {System.out.println(user.getUsername());System.out.println(user.getAccounts());}}