myBatis入门例子

淡淡的烟草味﹌ 2022-01-16 10:47 296阅读 0赞

1，本文采用的Mybatis框架版本为： mybatis-3.0.4.jar   
2， 以持久化一个简单的User bean为例   
User实体类的代码如下：

Java代码 ![收藏代码][Image 1]

1.  **package** bean; 
2.  
3.  **public** **class** User \{ 
4.  **private** String name; 
5.  **private** Integer age; 
6.  
7.  **public** String getName() \{ 
8.  **return** name; 
9.   \} 
10. **public** **void** setName(String name) \{ 
11. **this**.name = name; 
12.  \} 
13. **public** Integer getAge() \{ 
14. **return** age; 
15.  \} 
16. **public** **void** setAge(Integer age) \{ 
17. **this**.age = age; 
18.  \} 
19. **public** User(String name, Integer age) \{ 
20. **super**(); 
21. **this**.name = name; 
22. **this**.age = age; 
23.  \} 
24. 
25. **public** User() \{ 
26. **super**(); 
27.  \} //必须要有这个无参构造方法，不然根据UserMapper.xml中的配置，在查询数据库时，将不能反射构造出User实例 
28. \}

Java代码 ![收藏代码][Image 1]

User实体的映射器取名为UserMapper(接口)，其代码如下

Java代码 ![收藏代码][Image 1]

1.  **package** Mapper; 
2.  **import** bean.User; 
3.  
4.  **public** **interface** UserMapper \{ 
5.  **public** **void** insertUser(User user); 
6.  **public** User getUser(String name); 
7.  \}

Java代码 ![收藏代码][Image 1]

1.  **package** Mapper; 
2.  **import** bean.User; 
3.  
4.  **public** **interface** UserMapper \{ 
5.  **public** **void** insertUser(User user); 
6.  **public** User getUser(String name); 
7.  \}

注意，该接口类似于Hibernate中的DAO层接口，唯一不同的是，MyBatis中，只声明该接口就可以，不需要去实现.   
UserMapper映射器对应的配置文件如下(相当于Hibernate中的User.hbm.xml,当然这里面不是属性映射字段，而是直接是映射器中各种方法对应的sql语句)：

Xml代码 ![收藏代码][Image 1]

1.  **<?****xml** version="1.0" encoding="UTF-8" **?>**
2.  <!DOCTYPE mapper 
3.   PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 
4.   "http://mybatis.org/dtd/mybatis-3-mapper.dtd"**>**
5.  **<****mapper** namespace="Mapper.UserMapper"**>**
6.  
7.  **<****insert** id="insertUser" parameterType="User"**>**
8.   insert into vincent\_user(name,age) values(\#\{name\},\#\{age\}) 
9.  
10. **</****insert****>**
11. 
12. 
13. **<****select** id="getUser" resultType="User" parameterType="java.lang.String"**>**
14.  select \* from vincent\_user where name=\#\{name\} 
15. **</****select****>**
16. **</****mapper****>**

Xml代码 ![收藏代码][Image 1]

MyBatis的配置文件这里取名为mybatis-config.xml其配置代码如下(相当与Hibernate的hibernate.cfg.xml):

Xml代码 ![收藏代码][Image 1]

1.  **<?****xml** version="1.0" encoding="UTF-8"**?>**
2.  <!DOCTYPE configuration 
3.   PUBLIC "-//mybatis.org//DTD Config 3.0//EN" 
4.   "http://mybatis.org/dtd/mybatis-3-config.dtd"**>**
5.  
6.  **<****configuration****>**
7.  **<****settings****>**
8.  
9.  **<****setting** name="cacheEnabled" value="false" **/>**
10. **<****setting** name="useGeneratedKeys" value="true" **/>**
11. **<****setting** name="defaultExecutorType" value="REUSE" **/>**
12. **</****settings****>**
13. **<****typeAliases****>**
14. **<****typeAlias** alias="User" type="bean.User"**/>**
15. **</****typeAliases****>**
16. **<****environments** default="development"**>**
17. **<****environment** id="development"**>**
18. **<****transactionManager** type="jdbc"**/>**
19. **<****dataSource** type="POOLED"**>**
20. **<****property** name="driver" value="oracle.jdbc.driver.OracleDriver"**/>**
21. **<****property** name="url" value="jdbc:oracle:thin:@192.168.56.201:1521:system"**/>**
22. **<****property** name="username" value="vincent"**/>**
23. **<****property** name="password" value="1234"**/>**
24. **</****dataSource****>**
25. **</****environment****>**
26. **</****environments****>**
27. **<****mappers****>**
28. **<****mapper** resource="resource/UserMapper.xml" **/>**
29. **</****mappers****>**
30. **</****configuration****>**

Xml代码 ![收藏代码][Image 1]

加载配置文件得到sqlSessionFactory的工具类

Java代码 ![收藏代码][Image 1]

1.  **package** Util; 
2.  
3.  **import** java.io.IOException; 
4.  **import** java.io.Reader; 
5.  
6.  **import** org.apache.ibatis.io.Resources; 
7.  **import** org.apache.ibatis.session.SqlSessionFactory; 
8.  **import** org.apache.ibatis.session.SqlSessionFactoryBuilder; 
9.  
10. **public** **class** MyBatisUtil \{ 
11. **private** **final** **static** SqlSessionFactory sqlSessionFactory; 
12. **static** \{ 
13.  String resource = "resource/mybatis-config.xml"; 
14.  Reader reader = **null**; 
15. **try** \{ 
16.  reader = Resources.getResourceAsReader(resource); 
17.  \} **catch** (IOException e) \{ 
18.  System.out.println(e.getMessage()); 
19. 
20.  \} 
21.  sqlSessionFactory = **new** SqlSessionFactoryBuilder().build(reader); 
22.  \} 
23. 
24. **public** **static** SqlSessionFactory getSqlSessionFactory() \{ 
25. **return** sqlSessionFactory; 
26.  \} 
27. \}

Java代码 ![收藏代码][Image 1]

测试代码如下：

Java代码 ![收藏代码][Image 1]

1.  **package** TestMapper; 
2.  **import** org.apache.ibatis.session.SqlSession; 
3.  **import** org.apache.ibatis.session.SqlSessionFactory; 
4.  **import** org.junit.Test; 
5.  
6.  **public** **class** TestMapper \{ 
7.  **static** SqlSessionFactory sqlSessionFactory = **null**; 
8.  **static** \{ 
9.   sqlSessionFactory = MyBatisUtil.getSqlSessionFactory(); 
10.  \} 
11. 
12. @Test
13. **public** **void** testAdd() \{ 
14.  SqlSession sqlSession = sqlSessionFactory.openSession(); 
15. **try** \{ 
16.  UserMapper userMapper = sqlSession.getMapper(UserMapper.**class**); 
17.  User user = **new** User("tom",**new** Integer(5)); 
18.  userMapper.insertUser(user); 
19.  sqlSession.commit();//这里一定要提交，不然数据进不去数据库中 
20.  \} **finally** \{ 
21.  sqlSession.close(); 
22.  \} 
23.  \} 
24. 
25. @Test
26. **public** **void** getUser() \{ 
27.  SqlSession sqlSession = sqlSessionFactory.openSession(); 
28. **try** \{ 
29.  UserMapper userMapper = sqlSession.getMapper(UserMapper.**class**); 
30.  User user = userMapper.getUser("jun"); 
31.  System.out.println("name: "\+user.getName()+"|age: "\+user.getAge()); 
32.  \} **finally** \{ 
33.  sqlSession.close(); 
34.  \} 
35.  \} 
36. 
37. \}

Java代码 ![收藏代码][Image 1]

转载于:https://blog.51cto.com/quanju/1530283

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