Mybatis framework 3: dao layer development, Mapper dynamic proxy development, and mybatismapper

Mybatis framework 3: dao layer development, Mapper dynamic proxy development, and mybatismapper

Here is the most basic building: http://www.cnblogs.com/xuyiqing/p/8600888.html

Next we achieve a simple addition, deletion, modification, query: http://www.cnblogs.com/xuyiqing/p/8601506.html

 

However, it is found that the code is too repetitive.

Next we will integrate and implement DAO development:

 

I. Original DAO development:

package dao;import pojo.User;public interface UserDao {    public User selectUserById(Integer id);}

Package dao; import java. util. list; import org. apache. ibatis. session. sqlSession; import org. apache. ibatis. session. sqlSessionFactory; import pojo. user; public class UserDaoImpl implements UserDao {// inject private SqlSessionFactory sqlSessionFactory; public UserDaoImpl (SqlSessionFactory sqlSessionFactory) {this. sqlSessionFactory = sqlSessionFactory;} // query a User's public User selectUserById (Integer id) {SqlSession sqlSession = sqlSessionFactory by User id. openSession (); return sqlSession. selectOne ("test. findUserById ", id);} // you can use the User name to fuzzy query the public List <User> selectUserByUsername (Integer id) {SqlSession sqlSession = sqlSessionFactory. openSession (); return sqlSession. selectList ("test. findUserById ", id );}}

Test class:

package junit;import java.io.InputStream;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.junit.Before;import org.junit.Test;import dao.UserDao;import dao.UserDaoImpl;import pojo.User;public class DaoTest {    public SqlSessionFactory sqlSessionFactory;    @Before    public void before() throws Exception {        String resource = "sqlMapConfig.xml";        InputStream in = Resources.getResourceAsStream(resource);        sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);    }    @Test    public void testDao() throws Exception {        UserDao userDao = new UserDaoImpl(sqlSessionFactory);        User user = userDao.selectUserById(10);        System.out.println(user);    }}

 

 

However, we still find code duplication and resource waste:

So I thought of Mapper dynamic proxy development:

Package mapper; import pojo. user; public interface UserMapper {// follow the four principles // interface method name = User. id name in xml // return value type and Mapper. the return value type in the xml file must be consistent // The input parameter type of the method and Mapper. the input parameter types in xml must be consistent. // bind the namespace to this interface. // if an object is returned, call the selectOne method. // If the input parameter type is List, call the selectlist method public User findUserById (Integer id );}

 

UserMapper. xml

<? Xml version = "1.0" encoding = "UTF-8"?> <! DOCTYPE mapperPUBLIC "-// mybatis.org//DTD Mapper 3.0 //" http://mybatis.org/dtd/mybatis-3-mapper.dtd "> <! -- Write an SQL statement --> <mapper namespace = "mapper. UserMapper"> <! -- Query a user by ID --> <select id = "findUserById" parameterType = "Integer" resultType = "pojo. user "> select * from user where id =#{ v} </select> <! -- // Fuzzy query the user list by user name # {} select * from user where id =? Placeholder? = '5' $ {} select * from user where username like '% 5%' String concatenation --> <select id = "findUserByUsername" parameterType = "String" resultType = "pojo. user "> select * from user where username like" % "# {haha}" % "</select> <! -- Add user --> <insert id = "insertUser" parameterType = "pojo. user "> <selectKey keyProperty =" id "resultType =" Integer "order =" AFTER "> select LAST_INSERT_ID () </selectKey> insert into user (username, birthday, address, sex) values (# {username}, # {birthday}, # {address}, # {sex}) </insert> <! -- Update --> <update id = "updateUserById" parameterType = "pojo. user "> update user set username =#{ username}, sex =#{ sex}, birthday =#{ birthday }, address = # {address} where id = # {id} </update> <! -- Delete --> <delete id = "deleteUserById" parameterType = "Integer"> delete from user where id =#{ vvvvv} </delete> </mapper>

 

The main configuration file sqlMapConfig. xml:

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configurationPUBLIC "-//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" />            <dataSource type="POOLED">                <property name="driver" value="com.mysql.jdbc.Driver" />                <property name="url"                    value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />                <property name="username" value="root" />                <property name="password" value="xuyiqing" />            </dataSource>        </environment>    </environments>    <mappers>        <mapper resource="mapper/UserMapper.xml"/>     </mappers></configuration>

 

 

Test class:

Package junit; import java. io. inputStream; 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. test; import mapper. userMapper; import pojo. user; public class MybatisMapperTest {@ Test public void teid apper () throws Exception {String resource = "sqlMapConfig. xml "; InputStream in = Resources. getResourceAsStream (resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder (). build (in); SqlSession sqlSession = sqlSessionFactory. openSession (); // SqlSession automatically generates an implementation class UserMapper userMapper = sqlSession for the interface. getMapper (UserMapper. class); User user = userMapper. findUserById (10); System. out. println (user );}}

 

 

We recommend that you use Mapper for dynamic proxy development.