Detailed tutorial on the use of Mybatis

jar package required by Mybatis:

You need to reference two jar packages, one is mybatis The other one is MySQL-connector-Java , if it is an maven project, it is ok to add dependencies in pom as follows.

<dependency>
 <groupId>org.mybatis</groupId>
 <artifactId>mybatis</artifactId>
 <version>3.2.3</version>
</dependency>
<dependency>
 <groupId>mysql</groupId>
 <artifactId>mysql-connector-java</artifactId>
 <version>5.1.26</version>
</dependency>

Data preparation:

Build point data in MySQL for testing:

CREATE DATABASE mybatis_test;
CREATE TABLE user
(
 age INTEGER NOT NULL,
 name VARCHAR(64) NOT NULL DEFAULT ''
);
insert user values(18,'zhanjindong');
insert user values(20,'zhangsan');

Profile:

There are two types of configuration files required. The first type is mybatis-config.xml, which is a very simple configuration.

<?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> 
 <settings> 
  <!-- changes from the defaults for testing --> 
  <setting name="cacheEnabled" value="false" /> 
  <setting name="useGeneratedKeys" value="true" /> 
  <setting name="defaultExecutorType" value="REUSE" /> 
 </settings> 
 <typeAliases> 
  <typeAlias alias="User" type="test.mybatis.User"/> 
 </typeAliases> 
 <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://192.168.71.38:3306/mybatis_test"/> 
    <property name="username" value="root"/> 
    <property name="password" value="123456"/> 
   </dataSource> 
  </environment> 
 </environments> 
 <mappers> 
  <mapper resource="mappers/UserMapper.xml" /> 
 </mappers> 
</configuration>

The other class is the data access interface mapping file: UserMapper.xml in the example. This file can be found under src/main/resource or in the subdirectory mybatis.xml is specified by resource of the mappers/mapper node in mybatis-config.xml.

<?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="test.mybatis.UserMapper">
 <!--  Here, namespace It must be UserMapper Interface path"  -->
 <insert id="insertUser" parameterType="User">
  insert into user(name,age) values(#{name},#{age})
  <!--  Here, sql No semicolons at the end, otherwise" ORA-00911 "Error  -->
 </insert>
 <!--  Here, id Must and UserMapper The interface method name in the interface is the same  -->
 <select id="getUser" resultType="User" parameterType="java.lang.String">
  select * from user where name=#{name}
 </select>
</mapper>

The corresponding mapping file is the UserMapper interface under the namespace test.mybatis, which only defines the interface to access the data table:

package test.mybatis;
public interface UserMapper {
 public void insertUser(User user);
 public User getUser(String name);
}

You need 1 POJO: User.java

package test.mybatis;
public class User {
 private String name;
 private Integer age;
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public Integer getAge() {
  return age;
 }
 public void setAge(Integer age) {
  this.age = age;
 }
 public User(String name, Integer age) {
  super();
  this.name = name;
  this.age = age;
 }
 public User() {
  super();
 }
}

Testing:

The database operation by MyBatis USES a class called SqlSession, which is generated by SqlSessionFactory. It is recommended to maintain 1 SqlSessionFactory globally.

TestMyBatis.java
package test.mybatis;
import java.io.IOException;
import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class MyBatisUtil {
 private final static SqlSessionFactory sqlSessionFactory;
 static {
  String resource = "mybatis-config.xml";
  Reader reader = null;
  try {
   reader = Resources.getResourceAsReader(resource);
  } catch (IOException e) {
   System.out.println(e.getMessage());
  }
  sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
 }
 public static SqlSessionFactory getSqlSessionFactory() {
  return sqlSessionFactory;
 }
}

The test code is as follows:

TestMyBatis.java
package test.mybatis;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
public class TestMyBatis {
 static SqlSessionFactory sqlSessionFactory = null;
 static {
  sqlSessionFactory = MyBatisUtil.getSqlSessionFactory();
 }
 public static void main(String[] args) {
  testAdd();
  getUser();
 }
 public static void testAdd() {
  SqlSession sqlSession = sqlSessionFactory.openSession();
  try {
   UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
   User user = new User("lisi", new Integer(25));
   userMapper.insertUser(user);
   sqlSession.commit();//  Here, 1 Must submit, otherwise the data will not go into the database 
  } finally {
   sqlSession.close();
  }
 }
 public static void getUser() {
  SqlSession sqlSession = sqlSessionFactory.openSession();
  try {
   UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
   User user = userMapper.getUser("zhangsan");
   System.out.println("name: " + user.getName() + "|age: "
     + user.getAge());
  } finally {
   sqlSession.close();
  }
 }
}

1. mybatis logs using log4j, but turning debug on seems to have a significant performance impact.

2. The query cache of mybatis has a great impact on performance. The difference between enabled and not enabled is very large

The above is the site for you to introduce the detailed use of Mybatis tutorial, I hope to help you, if you have any questions welcome to give me a message, this site will timely reply to you!