mybatis implements the association relationship between tables and objects _ dynamic nodes
- 2020-10-07 18:41:47
- OfStack
Other tools or techniques needed:
Project management tool: Maven
Test run tool: Junit
Database: Derby
Maven Dependencies:
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.2.7</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.9</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.derby</groupId>
<artifactId>derby</artifactId>
<version>10.10.2.0</version>
</dependency>
<dependency>
<groupId>org.apache.derby</groupId>
<artifactId>derbyclient</artifactId>
<version>10.10.2.0</version>
</dependency>
</dependencies>
SQL table creation and data insertion (create 1 USER_TEST_TB_RELATIONSHIP table, then CopyUSER_TEST_TB table, Derby does not support column name changes in table structure, only do so) :
CREATE TABLE USER_TEST_TB_RELATIONSHIP(
USER_ID INT PRIMARY KEY,
USER_USERNAME VARCHAR(20) NOT NULL,
USER_PASSWORD VARCHAR(20) NOT NULL,
USER_NICKNAME VARCHAR(20) NOT NULL
);
INSERT INTO USER_TEST_TB_RELATIONSHIP(USER_ID,USER_USERNAME,USER_PASSWORD,USER_NICKNAME) SELECT ID,USERNAME,PASSWORD,NICKNAME FROM USER_TEST_TB;
Mybatis profile src/main/resource source directory
test-mybatis-configuration.xml
<?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>
<properties>
<property name="driver" value="org.apache.derby.jdbc.ClientDriver" />
<property name="url" value="jdbc:derby://localhost:1527/bjpowernode;create=true" />
</properties>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${driver}" />
<property name="url" value="${url}" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/bjpowernode/practice/UserMapper.xml" />
</mappers>
</configuration>
User. java object classes (src/main/java/com/bjpowernode/practice directory)
package com.bjpowernode.practice;
public class User
{
private Integer id;
private String username;
private String password;
private String nickname;
public Integer getId()
{
return id;
}
public void setId(Integer id)
{
this.id = id;
}
public String getUsername()
{
return username;
}
public void setUsername(String username)
{
this.username = username;
}
public String getPassword()
{
return password;
}
public void setPassword(String password)
{
this.password = password;
}
public String getNickname()
{
return nickname;
}
public void setNickname(String nickname)
{
this.nickname = nickname;
}
}
UserMapper. xml Mapper file (src/main/java/com. bjpowernode. practice directory)
<?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">
<mapper namespace="com.bjpowernode.practice.UserMapper">
<!-- Object properties and table fields -->
<resultMap id="userResultMap" type="com.bjpowernode.practice.User">
<result property="id" column="USER_ID"/>
<result property="username" column="USER_USERNAME"/>
<result property="password" column="USER_PASSWORD"/>
<result property="nickname" column="USER_NICKNAME"/>
</resultMap>
<select id="getUser" resultMap="userResultMap">
select *
from USER_TEST_TB_RELATIONSHIP
</select>
</mapper>
UserMapper. java Mapper class (src/main/java/com. bjpowernode. practice directory)
package com.bjpowernode.practice;
import java.util.List;
public interface UserMapper
{
public List<User> getUser();
}
The test class TestMyBatis. Java (src/test/java/com. bjpowernode. practice directory)
package com.bjpowernode.practice;
import java.io.InputStream;
import java.text.MessageFormat;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;
public class TestMyBatis
{
private String source;
private InputStream inputStream;
private SqlSessionFactory sqlSessionFactory;
@Before
public void setUp()
{
/**
* To prepare Mybatis Runtime environment
*/
source = "test-mybatis-configuration.xml";
inputStream = TestMyBatis.class.getClassLoader().getResourceAsStream(source);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void testGet()
{
try
{
// To obtain Session The connection
SqlSession session = sqlSessionFactory.openSession();
// To obtain Mapper
UserMapper userMapper = session.getMapper(UserMapper.class);
// According to User information
System.out.println("Test Get start...");
this.printUsers(userMapper.getUser());
System.out.println("Test Get finished...");
}
catch (Exception e)
{
e.printStackTrace();
}
}
/**
*
* Print user information to the console
*
* @param users
*/
private void printUsers(final List<User> users)
{
int count = 0;
for (User user : users)
{
System.out.println(MessageFormat.format("==User[{0}]=================", ++count));
System.out.println("User Id: " + user.getId());
System.out.println("User UserName: " + user.getUsername());
System.out.println("User Password: " + user.getPassword());
System.out.println("User nickname: " + user.getNickname());
}
}
}
conclusion