学习大神笔记之“MyBatis学习总结（二）”

MyBatis对表的增删改查操作

        主要有两种方式：基于XML实现和基于注解实现。

完整项目结构：

工具类：MyBatisUtil-------用于获取  sqlsession

 package me.gacl.test;

 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.getResourceAsStream(resource);
         SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
         return factory;
     }

     /**
      * 获取SqlSession
      * @return SqlSesstion
      * @throws
      */
     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);
     }
 }

  一、基于XML实现：（新建方法）

          思路总结：

在 userMapper.xml 文件中进行增删改查实现，

在测试类中映射xml文件中的sql（包名.文件名前缀.方法id）： String statement = "me.gacl.mapping.userMapper.addUser";

当新增成功，返回的retResult为1：int retResult = sqlSession.insert(statement,user);

代码实现：

           conf.xml----配置数据库

 <?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="liyangkun123" />
           </dataSource>
        </environment>
    </environments>
   <mappers>
      <mapper resource = "me/gacl/mapping/userMapper.xml" ></mapper>
   </mappers>

 </configuration>

         数据库驱动：<property name="driver" value="com.mysql.jdbc.Driver" />       

         <mapper   />==<mapper></mapper>

        userMapper.xml----实现增删改查

 <?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">

  <!-- 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的
  例如namespace="me.gacl.mapping.userMapper"就是me.gacl.mapping(包名)+userMapper(userMapper.xml文件去除后缀)-->

   <mapper namespace="me.gacl.mapping.userMapper">

       <!-- 在select标签中编写查询的SQL语句， 设置select标签的id属性为getUser，id属性值必须是唯一的，不能够重复使用parameterType属性指明查询时
                  使用的参数类型，resultType属性指明查询返回的结果集类型resultType="me.gacl.domain.User"就表示将查询结果封装成一个User类的对象返回
        User类就是users表所对应的实体类-->

      <!-- 根据id查询得到一个user对象 -->
      <select id="getUser" parameterType="int"  resultType="me.gacl.domain.User">
          select * from users where id=#{id}
      </select>

      <!-- 新增用户（Create） -->
      <insert id="addUser" parameterType="me.gacl.domain.User">
           insert into users(name,age)values(#{name},#{age})
      </insert>

      <!-- 修改用户（Update） -->
      <update id="updateUser" parameterType="me.gacl.domain.User">
            update users set name=#{name},age=#{age} where id=#{id}
      </update>

      <!-- 删除用户（Delete） -->
      <delete id="deleteUser" parameterType="int">
            delete from users where id=#{id}
      </delete>

      <!-- 查询所有用户 -->
      <select id="getAllUsers" resultType="me.gacl.domain.User">
            insert * from users
      </select>

  </mapper>

           测试类：TestCRUDByXmlMapper----单元测试验证

 package me.gacl.test;

 import org.apache.ibatis.session.SqlSession;
 import org.junit.Test;

 import me.gacl.domain.User;

 public class TestCRUDByXmlMapper {

     @Test
     public void testAdd(){
         SqlSession sqlSession = MyBatisUtil.getSqlSession();
         String statement = "me.gacl.mapping.userMapper.addUser";
         User user = new User();
         user.setName("用户孤傲苍狼");
         user.setAge(20);

         int retResult = sqlSession.insert(statement, user);
         sqlSession.close();
         System.out.println(retResult);
     }

         @Test
         public void testUpdate(){
             SqlSession sqlSession = MyBatisUtil.getSqlSession();
             String statement = "me.gacl.mapping.userMapper.updateUser";
             User user = new User();
             user.setId(2);
             user.setName("zhu");
             user.setAge(25);

             int retResult = sqlSession.update(statement, user);
             sqlSession.close();
             System.out.println(retResult);
         }

         @Test
         public void testdeleteUser(){
             SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
             String statement = "me.gacl.mapping.userMapper.deleteUser";

             int retResult =sqlSession.delete(statement,1);
             sqlSession.close();
             System.out.println(retResult);
         }
 }

SqlSession sqlSession = MyBatisUtil.getSqlSession(true);//获取session（内有链接数据库的配置），连上数据库，才能进行操作。

   二、基于注解实现：（新建方法）

写一个接口类定义sql映射，并且我们不用写接口实现，而是由MyBatis动态构建，我们只需要直接拿来使用即可。

接下来将接口类注册到配置文件中（conf.xml） ：

借鉴大神代码：

<!-- 注册UserMapper映射接口-->
          <mapper class="me.gacl.mapping.UserMapperI"/>

下一步测试类测试：

注意在新增之前要获得 sqlsession并且open，操作之后要close。

创建接口实例，

获取操作对象，修改操作信息

然后调用增删改查方法执行（借用大神代码）

代码实现：

         UserMapper.java----增删改查接口

 package me.gacl.mapping;

 import java.util.List;

 import org.apache.ibatis.annotations.Delete;
 import org.apache.ibatis.annotations.Insert;
 import org.apache.ibatis.annotations.Select;
 import org.apache.ibatis.annotations.Update;

 import me.gacl.domain.User;

 public interface UserMapperI {

    @Insert("insert into users(name,age) value(#{name},#{age})")
    public int add(User user);

    @Delete("delete from users where id=#{id}")
    public int deleteById(int id);

    @Select("select * from users where id=#{id}")
    public User selectById(int id);

    @Update("update users set name=#{name},age=#{age} where id=#{id}")
    public int updateById(User user);

    @Select("select * from users")
    public List<User> getAll();
 }

         注册到conf.xml文件中

<?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>
   <!-- 引用db.properties配置文件 -->
   <properties resource="me/gacl/test/db.properties" />

   <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="liyangkun123" />
          </dataSource>
       </environment>
   </environments>
  <mappers>
     <mapper resource = "me/gacl/mapping/userMapper.xml" ></mapper>
     <mapper class="me.gacl.mapping.UserMapperI" />
  </mappers>

</configuration>

         resource和class为包+名完整路径          

        TestCRUDByAnnotationMapper.java------测试类

 package me.gacl.test;

 import java.util.List;

 import org.apache.ibatis.session.SqlSession;
 import org.junit.Test;

 import me.gacl.domain.User;
 import me.gacl.mapping.UserMapperI;
 import me.gacl.test.MyBatisUtil;

 public class TestCRUDByAnnotationMapper {

     @Test
     public void testAdd(){
         SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
         UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
         User user = new User();
         user.setName("用户xdp");
         user.setAge(29);
         int add = mapper.add(user);

         sqlSession.close();
         System.out.println(add);
     }

     @Test
     public void testDelete(){
         SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
         UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
         int delete = mapper.deleteById(1);
         sqlSession.close();
         System.out.println(delete);
     }

     @Test
     public void testUpdate(){
         SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
         UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
         User user = new User();
         user.setId(2);
         user.setName("Linda");
         user.setAge(23);

         int update = mapper.updateById(user);
         sqlSession.close();
         System.out.println(update);
     }

     @Test
     public void testSelect(){
         SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
         UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
         User user = mapper.selectById(2);
         sqlSession.close();
         System.out.println(user);

     }

     @Test
     public void testSelectAll(){
         SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
         UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
         List<User> user = mapper.getAll();

         sqlSession.close();
         System.out.println(user);

     }
 }

注意事项：MyBatisUtil.java，conf.xml， 放到 util 包中时，调用出错，放到同一个包中，没有问题。

大神总结链接：http://www.cnblogs.com/xdp-gacl/p/4262895.html