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mybatis CRUD 联表查询缓存

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Mybatis

1.建立项目

源码下载地址:http://download.csdn.net/detail/dingsai88/8438185

参考资源：http://mybatis.github.io/mybatis-3/zh/index.html

2.建库

语句在源码SQL 文件夹下数据库mysql

createdatabase mybatis;

usemybatis;

createtable users(id int primary key auto_increment,name varchar(20),age int);

insertinto users(name,age)values('tom',12);

insertinto users(name,age)values('jack',11);

3.建配置文件

<?xml version="1.0"encoding="UTF-8"?>

<!DOCTYPEconfiguration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>



<environmentsdefault="development">

<environmentid="development">

<transactionManagertype="JDBC" />



<dataSourcetype="POOLED">

<propertyname="driver" value="com.mysql.jdbc.Driver" />

<propertyname="url" value="jdbc:mysql://localhost:3306/mybatis"/>

<propertyname="username" value="root" />

<propertyname="password" value="1111" />

</dataSource>

</environment>

</environments>

</configuration>

4.建立userMapper.xml

<?xmlversion="1.0"encoding="UTF-8"?>
<!DOCTYPEmapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mappernamespace="com.ding.test.User.userMapper">
<selectid="getUser"parameterType="int"
resultType="com.ding.test.User">
select * from users whereid=#{id}
</select>
</mapper>

5.Test

String resource ="conf.xml";
       //加载mybatis的配置文件（它也加载关联的映射文件）
       Reader reader = Resources.getResourceAsReader(resource);
       //构建sqlSession的工厂
       SqlSessionFactory sessionFactory = newSqlSessionFactoryBuilder().build(reader);
       //创建能执行映射文件中sql的 sqlSession
       SqlSession session = sessionFactory.openSession();
       //映射sql的标识字符串
       String statement ="com.ding.test.User.userMapper"+".selectUser";
       //执行查询返回一个唯一 user对象的sql
       User user = session.selectOne(statement, 1);
       System.out.println(user);

6.CRUD

userMapper.xml

<?xmlversion="1.0"encoding="UTF-8"?>
<!DOCTYPEmapperPUBLIC "-//mybatis.org//DTDMapper3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mappernamespace="com.ding.test.User.userMapper">
    <insertid="addUser"parameterType="com.ding.test.User">
       insert into users(name,age)values(#{name},#{age})
    </insert>
    <deleteid="deleteUser"parameterType="int">
       delete from users where id=#{id}
    </delete>
    <updateid="updateUser"parameterType="com.ding.test.User">
       update users set name=#{name},age=#{age} where id=#{id}
    </update>
    
    <selectid="getUser"parameterType="int"resultType="com.ding.test.User">
       select *
       from users where id=#{id}
    </select>
    <selectid="getAllUser"resultType="com.ding.test.User">
       select * from users
    </select>
</mapper>

Test2.java

package com.ding.test2;

import java.util.List;

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

import com.ding.test.User;
import com.ding.util.MybatisUtil;

public
class Test2 {

    /**
    * 测试insert方法
    */
    @Test
    @Ignore
    // 忽视
    public
void testAdd() {
       SqlSessionFactory factory = MybatisUtil.getFactory();
       // 默认是手动提交事务
       // SqlSession session =factory.openSession();// session.commit();
       // 是否自动提交
       SqlSession session = factory.openSession(true);
       //com.ding.test.User.userMapper是userMapper文件的的namespace命名空间
       // .addUser是命名空间下的ID
       String statment = "com.ding.test.User.userMapper.addUser";
       int insert = session.insert(statment,new User(-1,"dingsai3", 23));
       session.close();
       System.out.println("insert:" + insert);
    }

    @Test
    @Ignore
    public
void testUpdate() {
       SqlSessionFactory factory = MybatisUtil.getFactory();
       SqlSession session = factory.openSession(true);
       String statement = "com.ding.test.User.userMapper.updateUser";
       int update = session.update(statement,
              new User(4,"dingsaiUpdate4", 11));
       session.close();
       System.out.println("update:" + update);

    }

    @Test
    @Ignore
    public
void testDelete() {
       SqlSessionFactory factory = MybatisUtil.getFactory();
       SqlSession session = factory.openSession(true);
       int delete = session.delete("com.ding.test.User.userMapper.deleteUser",1);
       session.close();
       System.out.println("delete:" + delete);

    }

    @Test
    @Ignore
    public
void testGetUser() {
       SqlSessionFactory factory = MybatisUtil.getFactory();
       SqlSession session = factory.openSession(true);
       User user = session.selectOne("com.ding.test.User.userMapper.getUser",2);
       session.close();
       System.out.println("user:" + user);

    }
    @Test
    @Ignore
    public
void testGetAllUser(){
       SqlSessionFactory factory=MybatisUtil.getFactory();
       SqlSession session=factory.openSession(true);
       List<User> users=session.selectList("com.ding.test.User.userMapper.getAllUser", 1);
       for(User user:users){
           System.out.println("AllUser:" + user);
       }


    }


}

7.基于annotation的CRUD

UserMapperAnnation.java

packagecom.ding.test2;

importjava.util.List;

importorg.apache.ibatis.annotations.Delete;

importorg.apache.ibatis.annotations.Insert;

importorg.apache.ibatis.annotations.Select;

importorg.apache.ibatis.annotations.Update;

importcom.ding.test.User;

/**

* 基于注解的mapper接口

* @author Daniel

*

*/

publicinterface UserMapperAnnotation {

    @Insert("insert into users(name,age)values(#{name},#{age})")

    public int addUser(User user);

    @Delete("delete from users whereid=#{id}")

    public int deleteById(int id);

    @Update("update users setname=#{name},age=#{age} where id=#{id}")

    public int update(User user);

    @Select("select * from users whereid=#{id}")

    public User getById(int id);

    @Select("select * from users ")

    public List<User> getAll();

}

TestAnnotation.java

packagecom.ding.test2;

importjava.util.List;

importorg.apache.ibatis.session.SqlSession;

importorg.apache.ibatis.session.SqlSessionFactory;

importorg.junit.Ignore;

importorg.junit.Test;

importcom.ding.test.User;

importcom.ding.util.MybatisUtil;

/**

* 测试基于注解的mybatis

*

* @author Daniel

*

*/

publicclass TestAnnotation {

    /**

    * 测试insert方法

    */

    @Test

    @Ignore

    // 忽视

    public void testAdd() {

       SqlSessionFactory factory =MybatisUtil.getFactory();

       // 默认是手动提交事务

       // SqlSession session =factory.openSession();// session.commit();

       // 是否自动提交

       SqlSession session =factory.openSession(true);

       //反射生成UserMapperAnnotation对象

       UserMapperAnnotation mapper = session

              .getMapper(UserMapperAnnotation.class);

       int insert = mapper.addUser(new User(-1,"dingsai6", 66));

       session.close();

       System.out.println("insert:" +insert);

    }

    @Test

    @Ignore

    public void testUpdate() {

       SqlSessionFactory factory =MybatisUtil.getFactory();

       SqlSession session =factory.openSession(true);

       UserMapperAnnotation mapper = session

              .getMapper(UserMapperAnnotation.class);

       int update = mapper.update(new User(6,"dingsaiupdaete", 56));

       session.close();

       System.out.println("update:" +update);

    }

    @Test

    @Ignore

    public void testDelete() {

       SqlSessionFactory factory =MybatisUtil.getFactory();

       SqlSession session =factory.openSession(true);

       UserMapperAnnotation mapper = session

              .getMapper(UserMapperAnnotation.class);

       int delete = mapper.deleteById(5);

       session.close();

       System.out.println("delete:" +delete);

    }

    @Test

    @Ignore

    public void testGetUser() {

       SqlSessionFactory factory =MybatisUtil.getFactory();

       SqlSession session =factory.openSession(true);

       UserMapperAnnotation mapper = session

              .getMapper(UserMapperAnnotation.class);

       User user = mapper.getById(6);

       session.close();

       System.out.println("user:" +user);

    }

    @Test

    public void testGetAllUser() {

       SqlSessionFactory factory =MybatisUtil.getFactory();

       SqlSession session =factory.openSession(true);

       UserMapperAnnotation mapper = session

              .getMapper(UserMapperAnnotation.class);

       List<User> users = mapper.getAll();

       for (User user : users) {

           System.out.println("AllUser:"+ user);

       }

    }

}

Con.xml

<?xmlversion="1.0"encoding="UTF-8"?>
<!DOCTYPEconfigurationPUBLIC"-//mybatis.org//DTDConfig 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environmentsdefault="development">
       <environmentid="development">
           <transactionManagertype="JDBC"/>
           <dataSourcetype="POOLED">
              <propertyname="driver"value="com.mysql.jdbc.Driver"/>
              <propertyname="url"value="jdbc:mysql://localhost:3306/mybatis"/>
              <propertyname="username"value="root"/>
              <propertyname="password"value="111"/>
           </dataSource>
       </environment>
    </environments>
    <mappers>

       
       <mapperresource="com/ding/test2/userMapper.xml"/>
       
       <mapperclass="com.ding.test2.UserMapperAnnotation"/>
    </mappers>
</configuration>

8.添加DTD让XML自动完成提示

<!DOCTYPEmapper PUBLIC "-//mybatis.org//DTDMapper3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

Preferences --XML catalog-- Add

location=mybatis-3-mapper.dtd

key=-//mybatis.org//DTDMapper3.0//EN

9.数据库字段和bean字段不对应，修改别名

语句别名

<select id="getOrder" parameterType="int" resultType="Order">

    select order_id id, order_noorderNo,order_price price from orders where order_id=#{id}

    </select>

Order类

    private Integer id;

    private String orderNo;

    private float price;

xml映射别名

注意返回值变成resultMap类型

<mappernamespace="com.ding.bean.orderMapper">



    <resultMap id="orderResultMap"type="Order">

       <id property="id"column="order_id" />

       <result property="orderNo"column="order_no" />

       <result property="price"column="order_price" />

    </resultMap>





    

    <select id="getOrderMap"parameterType="int" resultMap="orderResultMap">

       select *

       from orders where order_id=#{id}

    </select>

</mapper>

10.联表查询一对一association:

1.联表查询一对一(1)

通过resultMap映射sql语句结果集为Bean

select* from class c ,teacher t where c.teacher_id=t.t_id and c.c_id=1;

Classes.java

private
int id;
    private Stringname;
    private Teacher
teacher;

Teacher.java

    private
int id;
    private String
name;

mysql>show create table teacher \G

***************************1. row ***************************

       Table: teacher

CreateTable: CREATE TABLE `teacher` (

`t_id` int(11) NOT NULL auto_increment,

`t_name` varchar(20) default NULL,

PRIMARY KEY (`t_id`)

)ENGINE=InnoDB DEFAULT CHARSET=latin1

mysql>show create table class \G

***************************1. row ***************************

       Table: class

CreateTable: CREATE TABLE `class` (

`c_id` int(11) NOT NULL auto_increment,

`c_name` varchar(20) default NULL,

`teacher_id` int(11) default NULL,

PRIMARY KEY (`c_id`),

KEY `fk_teacher_id` (`teacher_id`),

CONSTRAINT `fk_teacher_id` FOREIGN KEY(`teacher_id`) REFERENCES `teacher` (`t

_id`)

)ENGINE=InnoDB DEFAULT CHARSET=latin1

    

    <resultMap type="Classes"id="getClassMap">

       <id property="id"column="c_id" />

       <result property="name"column="c_name" />

       

       <associationproperty="teacher" javaType="Teacher">

           <id property="id"column="t_id" />

           <result property="name"column="t_name" />

       </association>

    </resultMap>

    

    <select id="getClass" parameterType="int"resultMap="getClassMap">

       SELECT *

       FROM class c ,teacher t WHEREc.teacher_id=t.t_id AND c.c_id=#{id};

    </select>

2.联表查询一对一(2)

把第一条语句的结果当成条件传给第二条语句，第二条语句的结果集通过resultMap映射给 bean的属性类

    

    <select id="getClass2"parameterType="int" resultMap="getClass2Map">

       SELECT * FROM class WHERE c_id=#{id}

    </select>

    

    <resultMap id="getClass2Map"type="Classes" >

       <id property="id"column="c_id" />

       <result property="name"column="c_name" />

       

       <associationproperty="teacher" column="teacher_id"

           select="getTeacher">

       </association>

    </resultMap>

   

    <select id="getTeacher" parameterType="int"resultType="Teacher">

       SELECT t_id id , t_name name FROMteacher WHERE t_id=#{id}

    </select>

字段说明:

association:用于一对一的关联查询

property:对象属性的名称

javaType:对象属性的类型

column:所对应的数据库字段名

select:另一个查询的结果集

11.联表查询一对多

1.联表查询一对多(1)

Classes.java

    private
int id;
    private Stringname;
    private Teacherteacher;
    privateList<Student>
students;

oneToManyMapper.xml



    <select id="oneToMany1"parameterType="int" resultMap="getClassesMapOneToMany">

       SELECT *

       FROM class c, student s ,teacher t WHEREc.teacher_id=t.t_id AND

       c.c_id=s.class_id AND c.c_id=#{id};

    </select>

    <resultMap type="Classes"id="getClassesMapOneToMany">

       <id property="id"column="c_id" />

       <result property="name"column="c_name" />

       <associationproperty="teacher" javaType="Teacher">

           <id property="id"column="t_id" />

           <result property="name"column="t_name" />

       </association>

       <collection property="students"ofType="Student">

           <id property="id"column="s_id" />

           <result property="name"column="s_name" />

       </collection>

    </resultMap>

1.联表查询一对多(2)

<select id="oneToMany2"parameterType="int" resultMap="getClassMapOneToMany2">

       SELECT * FROM class WHERE c_id=#{id};

    </select>

    <resultMap type="Classes"id="getClassMapOneToMany2">

       <id property="id"column="c_id" />

       <result property="name"column="c_name" />

       <associationproperty="teacher" select="getTeacher"

           column="teacher_id" />

       <collection property="students"select="getStudent"ofType="Student"column="c_id"></collection>

    </resultMap>

    <select id="getTeacher"parameterType="int" resultType="Teacher">

       SELECT t_id id ,t_name name FROM teacher WHERE t_id=#{id};

    </select>

    <select id="getStudent"parameterType="int"   resultType="Student">

       SELECT s_id id,s_name name FROM student WHERE class_id=#{id};

    </select>

12.动态模糊查询

User.java

    private
int id;
    private String
name;

ConditionUser.java

    private Stringname;
    private
int minAge;
    private
int maxAge;

classMapperLike.xml

大于等于between and

Like用like

    <select id="getUser" parameterType="ConditionUser"resultType="com.ding.bean.User">

       select * from d_user where       age between#{minAge}
and #{maxAge}

       <iftest="name!=null">

       and name like #{name}

       </if>

    </select>

调用:

"com.ding.bean.classMapperLike.getUser",new ConditionUser("%Tom%",0, 50));

choose,when, otherwise,trim, where, set 等在：
http://mybatis.github.io/mybatis-3/zh/dynamic-sql.html

13.调用存储过程

#创建存储过程(查询得到男性或女性的数量, 如果传入的是 0 就女性否则是男性)

DELIMITER$

CREATEPROCEDURE mybatis.ges_user_count(IN sex_id INT, OUT user_count INT)

BEGIN

IFsex_id=0 THEN

SELECTCOUNT(*) FROM mybatis.p_user WHERE p_user.sex='女' INTO user_count;

ELSE

SELECTCOUNT(*) FROM mybatis.p_user WHERE p_user.sex='男' INTO user_count;

ENDIF;

END

$

#调用存储过程

DELIMITER;

SET@user_count = 0;

CALLmybatis.ges_user_count(1, @user_count);

SELECT@user_count;

procedureMapper.xml配置:

传入parameterMap参数需要statementType=”CALLABLE”

    

    <select id="getUser" parameterMap="getUserCountMap"statementType="CALLABLE">

       CALLmybatis.ges_user_count(?,?);

    </select>



    <parameterMap type="java.util.Map"id="getUserCountMap">

       <parameter property="sexid" mode="IN" jdbcType="INTEGER" />

       <parameter property="usercount" mode="OUT" jdbcType="INTEGER" />

    </parameterMap>

调用方式:放入map的需要和配置的parameterMap定义的一样

Map<String,Integer> parameterMap=newHashMap<String,Integer>();

       //传入的参数

       parameterMap.put("sexid",1);

       //返回值参数

       parameterMap.put("usercount",-1);

       session.selectList(

              "com.ding.bean.classMapperProcedure.getUser",parameterMap);

       session.close();

       System.out.println(parameterMap.get("usercount"));

14.缓存

cacheMapper.xml

一级缓存:

默认开启:session级别

更新情况:

1.参数值改变，2.调用session.clearCache();3.调用增删改CUD 4.不是同一个session对象不会用一级缓存

<mappernamespace="com.ding.bean.cache.cacheMapper">



<cache/>

    <!—一级缓存默认开启 -->

    <select id="getUser"parameterType="int"resultType="com.ding.bean.cache.CUser">

       select * from c_user   where id=#{id}

    </select>

    <update id="updateUser"parameterType="com.ding.bean.cache.CUser">

       update c_user set

       name=#{name}, age=#{age} where id=#{id}

    </update>

</mapper>

调用：

/**

    * 一级缓存:session级别默认开启

    *

    * 1.参数值改变，2.调用session.clearCache();3.调用增删改CUD

    */

    @Test

    @Ignore

    public void testOneCache() {

       SqlSessionFactory factory =MybatisUtil.getFactory();

       SqlSession session =factory.openSession(true);

       CUser user = session.selectOne(

              "com.ding.bean.cache.cacheMapper.getUser",1);

       System.out.println(user);

       // 1.参数值改变查询语句只执行一次，第二次不会执行，直接调用session里的值

       // user =

       //session.selectOne("com.ding.bean.cache.cacheMapper.getUser",2);

       // 2.调用清理cache

       // session.clearCache();

       // 3.调用增删改 cud

       //session.update("com.ding.bean.cache.cacheMapper.updateUser", new

       // CUser(1,"TOM update",33));

       // 4.不是同一个session对象不会用一级缓存

       // SqlSession session1 =factory.openSession(true);

       // user =

       //session1.selectOne("com.ding.bean.cache.cacheMapper.getUser",1);

       user =session.selectOne("com.ding.bean.cache.cacheMapper.getUser", 1);

       System.out.println(user);

    }

二级缓存:

在映射文件里加入:

<cache/>

    /**

    * 二级缓存:对应映射文件级别sessionFactory级别

    */

    @Test

    public void testTwoCache() {

       SqlSessionFactory factory =MybatisUtil.getFactory();

       SqlSession session =factory.openSession(true);

       SqlSession session1 =factory.openSession();

       CUser user = session.selectOne(

              "com.ding.bean.cache.cacheMapper.getUser",1);

       System.out.println(user);

       //必须commit不然不会命中二级缓存

        session.commit();

       // 4.不是同一个session对象不会用一级缓存 Cache Hit Ratio[com.ding.bean.cache.cacheMapper]: 0.5



       user =session1.selectOne("com.ding.bean.cache.cacheMapper.getUser", 1);

       System.out.println("TEST:" +user);

    }

不同的sqlSession会有缓存，session.commit增加缓存命中率

二级缓存其他配置:
http://mybatis.github.io/mybatis-3/zh/sqlmap-xml.html#cache

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mybatis CRUD 联表查询 缓存