mybatis 最简单实例

1. 配置文件

 
  <?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" 
  />   
  
             
  < 
  dataSource  
  type 
  ="POOLED" 
  >   
  
                 
  < 
  property  
  name 
  ="driver" 
   value 
  ="com.mysql.jdbc.Driver" 
  />   
  
                 
  < 
  property  
  name 
  ="url" 
   value 
  ="jdbc:mysql://localhost:3306/orcl" 
  />   
  
                 
  < 
  property  
  name 
  ="username" 
   value 
  ="root" 
  />   
  
                 
  < 
  property  
  name 
  ="password" 
   value 
  ="xxxxxx" 
  />   
  
             
  </ 
  dataSource 
  >   
  
         
  </ 
  environment 
  >   
  
     
  </ 
  environments 
  >   
  
       
  
       
  
     
  < 
  mappers 
  > 
  
         
  < 
  mapper  
  resource 
  ="com/xiamen/domain/person.xml" 
    
  />         
  
     
  </ 
  mappers 
  >   
  
       
  
</ 
  configuration 
  >   
 

 包括两个部分 1. 数据库连接 2. sql映射文件Mapper

 

 2. ORM对象

 
  
    package com.xiamen.domain; 
  import java.io.Serializable; 
  

public class Person implements Serializable { 
  

    private int personId; 
  
    private String name; 
  
    private String age; 
  
     
  
    public int getPersonId() { 
  
        return personId; 
  
    } 
  
    public void setPersonId(int personId) { 
  
        this.personId = personId; 
  
    } 
  
    public String getName() { 
  
        return name; 
  
    } 
  
    public void setName(String name) { 
  
        this.name = name; 
  
    } 
  
    public String getAge() { 
  
        return age; 
  
    } 
  
    public void setAge(String age) { 
  
        this.age = age; 
  
    } 
  

     
  
} 
 

3. sql映射文件

 
  <?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.xiamen.mapper.PersonMapper" 
  > 
  
  
  < 
  select  
  id 
  ="getPersonById" 
   parameterType 
  ="int" 
   resultType 
  ="com.xiamen.domain.Person" 
  > 
  
       select * from person where personId=#{id} 
  
  
  </ 
  select 
  > 
  
  
  < 
  insert  
  id 
  ="insertvalues" 
   parameterType 
  ="com.xiamen.domain.Person" 
  > 
  
     insert into person (personId,name,age) values (#{personId},#{name},#{age}) 
  
  
  </ 
  insert 
  > 
  
</ 
  mapper 
  > 
 

注意mapper的namespace的名字是mapper对象的完整路径名com.xiamen.mapper.PersonMapper(这样session就可以getMapper了)

因为mybatis的作用就是：使得接口绑定成为可能 

 

4. mapper接口

映射器是创建绑定映射语句的接口,所以mapper接口就是映射器

 
  
    package com.xiamen.mapper; 
  import com.xiamen.domain.Person; 
  

public interface PersonMapper  
  
{ 
  
    Person getPersonById(int id); 
  
} 
 

5. 测试类

         String resource = "config/mybatis.xml";

Reader reader = Resources.getResourceAsReader(resource);
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader);
        SqlSession session = null;
        try {
            session = factory.openSession();
            Person person = (Person) session.selectOne(
            "com.xiamen.mapper.PersonMapper.getPersonById", 1);
            if(person == null)
                System.out.println("null");
            else
                System.out.println(person.toString());
            } 
        finally {
            session.close();
            }
        try {
            session = factory.openSession();
            PersonMapper mapper = session.getMapper(PersonMapper.class);
            Person person = mapper.getPersonById(1);
            if(person == null)
                System.out.println("null");
            else
                System.out.println(person.toString()); 
            } finally {
            session.close();
            }