Mybatis中配置Mapper的方法-CFANZ编程社区

现假设我有这样一个实体类：

Java代码

1. package com.tiantian.mybatis.model; 
2. 
3. public class User { 
4. 
5. private int id; 
6. private String name; 
7. private int age; 
8. public int getId() { 
9. return id; 
10. } 
11. public void setId(int id) { 
12. this.id = id; 
13. } 
14. public String getName() { 
15. return name; 
16. } 
17. public void setName(String name) { 
18. this.name = name; 
19. } 
20. public int getAge() { 
21. return age; 
22. } 
23. public void setAge(int age) { 
24. this.age = age; 
25. } 
26. 
27. }

package com.tiantian.mybatis.model; public class User { private int id; private String name; private int age; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } }

它对应的数据库表结构是这样的：

然后我要利用Mybatis对它做一个简单的增删改查操作，那么如果利用xml配置Mapper的方式来定义的话，我对应的UserMapper.xml文件会是这样：

Xml代码

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. 
6. <mapper  namespace="com.tiantian.mybatis.mapper.UserMapper"> 
7. <insert  id="insertUser"  parameterType="User"  useGeneratedKeys="true"  keyColumn="id"> 
8. insert into t_user(name, age) values(#{name}, #{age}) 
9. </insert> 
10. 
11. <update  id="updateUser"  parameterType="User"> 
12. update t_user set name=#{name},  age=#{age} where id=#{id} 
13. </update> 
14. 
15. <select  id="findById"  parameterType="int"  resultType="User"> 
16. select * from t_user where id=#{id} 
17. </select> 
18. 
19. <delete  id="deleteUser"  parameterType="int"> 
20. delete from t_user where id=#{id} 
21. </delete> 
22. </mapper>

<?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.tiantian.mybatis.mapper.UserMapper"> <insert id="insertUser" parameterType="User" useGeneratedKeys="true" keyColumn="id"> insert into t_user(name, age) values(#{name}, #{age}) </insert> <update id="updateUser" parameterType="User"> update t_user set name=#{name}, age=#{age} where id=#{id} </update> <select id="findById" parameterType="int" resultType="User"> select * from t_user where id=#{id} </select> <delete id="deleteUser" parameterType="int"> delete from t_user where id=#{id} </delete></mapper>

如果使用接口加注解的方式，那么我们的UserMapper接口应该这样定义：

Java代码

1. package com.tiantian.mybatis.mapperinterface; 
2. 
3. import org.apache.ibatis.annotations.Delete; 
4. import org.apache.ibatis.annotations.Insert; 
5. import org.apache.ibatis.annotations.Select; 
6. import org.apache.ibatis.annotations.Update; 
7. 
8. import com.tiantian.mybatis.model.User; 
9. 
10. public interface UserMapper { 
11. 
12. @Insert("insert into t_user(name, age) values(#{name}, #{age})") 
13. public void insertUser(User user); 
14. 
15. @Update("update t_user set name=#{name}, age=#{age} where id=#{id}") 
16. public void updateUser(User user); 
17. 
18. @Select("select * from t_user where id=#{id}") 
19. public User findById(int id); 
20. 
21. @Delete("delete from t_user where id=#{id}") 
22. public void deleteUser(int id); 
23. 
24. }

package com.tiantian.mybatis.mapperinterface; import org.apache.ibatis.annotations.Delete;import org.apache.ibatis.annotations.Insert;import org.apache.ibatis.annotations.Select;import org.apache.ibatis.annotations.Update; import com.tiantian.mybatis.model.User; public interface UserMapper { @Insert("insert into t_user(name, age) values(#{name}, #{age})") public void insertUser(User user); @Update("update t_user set name=#{name}, age=#{age} where id=#{id}") public void updateUser(User user); @Select("select * from t_user where id=#{id}") public User findById(int id); @Delete("delete from t_user where id=#{id}") public void deleteUser(int id); }

注意看这里我故意把UserMapper接口的namespace也就是它的包名置为与UserMapper.xml的namespace属性不一样。这主要是为了要更好的讲以下的内容。

接下来要做的就是把Mapper信息注册到Mybatis的配置中，告诉Mybatis我们定义了哪些Mapper信息。这主要是在Mybatis的配置文件中通过mappers元素来进行的。在以前版本的Mybatis中我们在Mybatis的配置文件中需要这样定义Mapper信息资源的位置。

Xml代码

1. <mappers> 
2. <mapper  resource="com/tiantian/mybatis/mapper/UserMapper1.xml"/> 
3. <mapper  url="file:///E:/UserMapper.xml"/> 
4. </mappers>

这主要是通过mapper元素的resource和url属性来指定的，resource属性指定的是相对于跟类路径下的资源，url属性指定的是通过URL可以获取到的资源。这有一点不好的地方，当我们使用Mapper接口加注解来定义当前Mapper的操作信息时，我们还需要定义一个与它对应的Mapper.xml文件。如：

Xml代码

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="com.tiantian.mybatis.mapperinterface.UserMapper"> 
6. 
7. </mapper>

Java代码

1. package com.tiantian.mybatis.mapperinterface; 
2. 
3. import org.apache.ibatis.annotations.Delete; 
4. import org.apache.ibatis.annotations.Insert; 
5. import org.apache.ibatis.annotations.Select; 
6. import org.apache.ibatis.annotations.Update; 
7. 
8. import com.tiantian.mybatis.model.User; 
9. 
10. public interface UserMapper { 
11. 
12. @Insert("insert into t_user(name, age) values(#{name}, #{age})") 
13. public void insertUser(User user); 
14. 
15. @Update("update t_user set name=#{name}, age=#{age} where id=#{id}") 
16. public void updateUser(User user); 
17. 
18. @Select("select * from t_user where id=#{id}") 
19. public User findById(int id); 
20. 
21. @Delete("delete from t_user where id=#{id}") 
22. public void deleteUser(int id); 
23. 
24. }

我发现在现在使用的这个Mybatis3.2.1中这个问题已经得到了改善，现在我们在定义基于接口的定义的Mapper时可以通过一个class属性来指定接口。

Xml代码

1. <mappers> 
2. <mapper  class="com.tiantian.mybatis.mapperinterface.UserMapper"/> 
3. </mappers>

除了通过class属性指定Mapper接口外，Mybatis还为我们提供了一个可以同时指定多个Mapper接口的方法。在现在的Mybatis版本中我们可以在mappers元素下面定义一个package子元素，用以指定Mapper接口所在的包，这样Mybatis就会把这个包下面的所有Mapper接口都进行注册。

Xml代码

1. <mappers> 
2. <package  name="com.tiantian.mybatis.mapperinterface"/> 
3. </mappers>

这里的一个package只针对于一个包。当在多个包里面定义有Mapper接口时，我们需要定义对应的多个package元素。

这四种注册Mapper的方式就是我想在这篇文章中表达的。总结一下：

Xml代码

1. <mappers> 
2. <!-- 通过package元素将会把指定包下面的所有Mapper接口进行注册 --> 
3. <package  name="com.tiantian.mybatis.mapperinterface"/> 
4. <!-- 通过mapper元素的resource属性可以指定一个相对于类路径的Mapper.xml文件 --> 
5. <mapper  resource="com/tiantian/mybatis/mapper/UserMapper.xml"/> 
6. <!-- 通过mapper元素的url属性可以指定一个通过URL请求道的Mapper.xml文件 --> 
7. <mapper  url="file:///E:/UserMapper.xml"/> 
8. <!-- 通过mapper元素的class属性可以指定一个Mapper接口进行注册 --> 
9. <mapper  class="com.tiantian.mybatis.mapperinterface.UserMapper"/> 
10. </mappers>

当使用mapper元素进行Mapper定义的时候需要注意：mapper的三个属性resource、url和class对于每个mapper元素只能指定一个，要么指定resource属性，要么指定url属性，要么指定class属性，不能都指定，也不能都不指定。

下面将对上面的代码给出一些对应的测试代码。先贴出测试对应的Mybatis的配置文件：

Xml代码

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. <configuration> 
6. 
7. <properties  resource="config/jdbc.properties"></properties> 
8. <typeAliases> 
9. <package  name="com.tiantian.mybatis.model"/> 
10. </typeAliases> 
11. <environments  default="development"> 
12. <environment  id="development"> 
13. <transactionManager  type="JDBC" /> 
14. <dataSource  type="POOLED"> 
15. <property  name="driver"  value="${jdbc.driver}" /> 
16. <property  name="url"  value="${jdbc.url}" /> 
17. <property  name="username"  value="${jdbc.username}" /> 
18. <property  name="password"  value="${jdbc.password}" /> 
19. </dataSource> 
20. </environment> 
21. </environments> 
22. <mappers> 
23. <package  name="com.tiantian.mybatis.mapperinterface"/> 
24. <mapper  resource="com/tiantian/mybatis/mapper/UserMapper.xml"/> 
25. </mappers> 
26. </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> <properties resource="config/jdbc.properties"></properties> <typeAliases> <package name="com.tiantian.mybatis.model"/> </typeAliases> <environments default="development"> <environment id="development"> <transactionManager type="JDBC" /> <dataSource type="POOLED"> <property name="driver" value="${jdbc.driver}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> </dataSource> </environment> </environments> <mappers> <package name="com.tiantian.mybatis.mapperinterface"/> <mapper resource="com/tiantian/mybatis/mapper/UserMapper.xml"/> </mappers></configuration>

1.对于使用xml方式定义的UserMapper.xml，然后直接使用SqlSession访问定义在其中的statement的测试：

Java代码

1. package com.tiantian.mybatis.test; 
2. 
3. import org.apache.ibatis.session.SqlSession; 
4. import org.apache.ibatis.session.SqlSessionFactory; 
5. import org.junit.Before; 
6. import org.junit.Test; 
7. 
8. import com.tiantian.mybatis.model.User; 
9. import com.tiantian.mybatis.util.Util; 
10. 
11. /** 
12. * 
13. * 这个类主要用来测试直接使用SqlSession访问定义在UserMapper.xml文件中的statement 
14. * 
15. */ 
16. public class UserMapperTest { 
17. 
18. SqlSessionFactory sqlSessionFactory = null; 
19. 
20. @Before
21. public void before() { 
22. sqlSessionFactory = Util.getSqlSessionFactory(); 
23. } 
24. 
25. @Test
26. public void testInsert() { 
27. SqlSession sqlSession = sqlSessionFactory.openSession(); 
28. try { 
29. User user = new User(); 
30. user.setName("张三"); 
31. user.setAge(30); 
32. sqlSession.insert("com.tiantian.mybatis.mapper.UserMapper.insertUser", user); 
33. sqlSession.commit(); 
34. } finally { 
35. sqlSession.close(); 
36. } 
37. } 
38. 
39. @Test
40. public void testUpdate() { 
41. SqlSession sqlSession = sqlSessionFactory.openSession(); 
42. try { 
43. User user = new User(); 
44. user.setId(1); 
45. user.setName("李四"); 
46. user.setAge(34); 
47. sqlSession.update("com.tiantian.mybatis.mapper.UserMapper.updateUser", user); 
48. sqlSession.commit(); 
49. } finally { 
50. sqlSession.close(); 
51. } 
52. } 
53. 
54. @Test
55. public void testFind() { 
56. SqlSession sqlSession = sqlSessionFactory.openSession(); 
57. try { 
58. User user = sqlSession.selectOne("com.tiantian.mybatis.mapper.UserMapper.findById", 1); 
59. System.out.println(user.getId() + "--" + user.getName() + "--" + user.getAge()); 
60. } finally { 
61. sqlSession.close(); 
62. } 
63. } 
64. 
65. @Test
66. public void testDelele() { 
67. SqlSession sqlSession = sqlSessionFactory.openSession(); 
68. try { 
69. sqlSession.delete("com.tiantian.mybatis.mapper.UserMapper.deleteUser",  2); 
70. sqlSession.commit(); 
71. } finally { 
72. sqlSession.close(); 
73. } 
74. } 
75. 
76. }

package com.tiantian.mybatis.test; import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.junit.Before;import org.junit.Test; import com.tiantian.mybatis.model.User;import com.tiantian.mybatis.util.Util; /** * * 这个类主要用来测试直接使用SqlSession访问定义在UserMapper.xml文件中的statement * */public class UserMapperTest { SqlSessionFactory sqlSessionFactory = null; @Before public void before() { sqlSessionFactory = Util.getSqlSessionFactory(); } @Test public void testInsert() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { User user = new User(); user.setName("张三"); user.setAge(30); sqlSession.insert("com.tiantian.mybatis.mapper.UserMapper.insertUser", user); sqlSession.commit(); } finally { sqlSession.close(); } } @Test public void testUpdate() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { User user = new User(); user.setId(1); user.setName("李四"); user.setAge(34); sqlSession.update("com.tiantian.mybatis.mapper.UserMapper.updateUser", user); sqlSession.commit(); } finally { sqlSession.close(); } } @Test public void testFind() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { User user = sqlSession.selectOne("com.tiantian.mybatis.mapper.UserMapper.findById", 1); System.out.println(user.getId() + "--" + user.getName() + "--" + user.getAge()); } finally { sqlSession.close(); } } @Test public void testDelele() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { sqlSession.delete("com.tiantian.mybatis.mapper.UserMapper.deleteUser", 2); sqlSession.commit(); } finally { sqlSession.close(); } } }

2.对于使用Mapper接口加对应的注解来定义的Mapper信息直接使用SqlSession访问Mapper接口中使用注解定义好的statement的测试：

Java代码

1. package com.tiantian.mybatis.test; 
2. 
3. import org.apache.ibatis.session.SqlSession; 
4. import org.apache.ibatis.session.SqlSessionFactory; 
5. import org.junit.Before; 
6. import org.junit.Test; 
7. 
8. import com.tiantian.mybatis.model.User; 
9. import com.tiantian.mybatis.util.Util; 
10. 
11. /** 
12. * 
13. *这个类是测试直接使用SqlSession访问UserMapper接口中使用注解定义好的statement 
14. * 
15. */ 
16. public class UserMapperTest2 { 
17. 
18. SqlSessionFactory sqlSessionFactory = null; 
19. 
20. @Before
21. public void before() { 
22. sqlSessionFactory = Util.getSqlSessionFactory(); 
23. } 
24. 
25. @Test
26. public void testInsert() { 
27. SqlSession sqlSession = sqlSessionFactory.openSession(); 
28. try { 
29. User user = new User(); 
30. user.setName("张三"); 
31. user.setAge(30); 
32. sqlSession.insert("com.tiantian.mybatis.mapperinterface.UserMapper.insertUser", user); 
33. sqlSession.commit(); 
34. } finally { 
35. sqlSession.close(); 
36. } 
37. } 
38. 
39. @Test
40. public void testUpdate() { 
41. SqlSession sqlSession = sqlSessionFactory.openSession(); 
42. try { 
43. User user = new User(); 
44. user.setId(1); 
45. user.setName("李四"); 
46. user.setAge(34); 
47. sqlSession.update("com.tiantian.mybatis.mapperinterface.UserMapper.updateUser", user); 
48. sqlSession.commit(); 
49. } finally { 
50. sqlSession.close(); 
51. } 
52. } 
53. 
54. @Test
55. public void testFind() { 
56. SqlSession sqlSession = sqlSessionFactory.openSession(); 
57. try { 
58. User user = sqlSession.selectOne("com.tiantian.mybatis.mapperinterface.UserMapper.findById", 1); 
59. System.out.println(user.getId() + "--" + user.getName() + "--" + user.getAge()); 
60. } finally { 
61. sqlSession.close(); 
62. } 
63. } 
64. 
65. @Test
66. public void testDelele() { 
67. SqlSession sqlSession = sqlSessionFactory.openSession(); 
68. try { 
69. sqlSession.delete("com.tiantian.mybatis.mapperinterface.UserMapper.deleteUser", 3); 
70. sqlSession.commit(); 
71. } finally { 
72. sqlSession.close(); 
73. } 
74. } 
75. 
76. }

package com.tiantian.mybatis.test; import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.junit.Before;import org.junit.Test; import com.tiantian.mybatis.model.User;import com.tiantian.mybatis.util.Util; /** * *这个类是测试直接使用SqlSession访问UserMapper接口中使用注解定义好的statement * */public class UserMapperTest2 { SqlSessionFactory sqlSessionFactory = null; @Before public void before() { sqlSessionFactory = Util.getSqlSessionFactory(); } @Test public void testInsert() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { User user = new User(); user.setName("张三"); user.setAge(30); sqlSession.insert("com.tiantian.mybatis.mapperinterface.UserMapper.insertUser", user); sqlSession.commit(); } finally { sqlSession.close(); } } @Test public void testUpdate() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { User user = new User(); user.setId(1); user.setName("李四"); user.setAge(34); sqlSession.update("com.tiantian.mybatis.mapperinterface.UserMapper.updateUser", user); sqlSession.commit(); } finally { sqlSession.close(); } } @Test public void testFind() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { User user = sqlSession.selectOne("com.tiantian.mybatis.mapperinterface.UserMapper.findById", 1); System.out.println(user.getId() + "--" + user.getName() + "--" + user.getAge()); } finally { sqlSession.close(); } } @Test public void testDelele() { SqlSession sqlSession = sqlSessionFactory.openSession(); try { sqlSession.delete("com.tiantian.mybatis.mapperinterface.UserMapper.deleteUser", 3); sqlSession.commit(); } finally { sqlSession.close(); } } }

3.对于使用Mapper接口加注解定义好的Mapper信息通过SqlSession获取其对应的Mapper接口来操作其中定义好的statement的测试：

Java代码

1. package com.tiantian.mybatis.test; 
2. 
3. import org.apache.ibatis.session.SqlSession; 
4. import org.apache.ibatis.session.SqlSessionFactory; 
5. import org.junit.Before; 
6. import org.junit.Test; 
7. 
8. import com.tiantian.mybatis.mapperinterface.UserMapper; 
9. import com.tiantian.mybatis.model.User; 
10. import com.tiantian.mybatis.util.Util; 
11. 
12. /** 
13. * 
14. *这个类是测试使用SqlSession获取UserMapper接口来执行使用注解定义在UserMapper接口中的statement 
15. * 
16. */ 
17. public class UserMapperTest3 { 
18. 
19. SqlSessionFactory sqlSessionFactory = null; 
20. 
21. @Before
22. public void before() { 
23. sqlSessionFactory = Util.getSqlSessionFactory(); 
24. } 
25. 
26. @Test
27. public void testInsert() { 
28. SqlSession sqlSession = sqlSessionFactory.openSession(); 
29. try { 
30. User user = new User(); 
31. user.setName("张三"); 
32. user.setAge(30); 
33. UserMapper userMapper = sqlSession.getMapper(UserMapper.class); 
34. userMapper.insertUser(user); 
35. sqlSession.commit(); 
36. } finally { 
37. sqlSession.close(); 
38. } 
39. } 
40. 
41. @Test
42. public void testUpdate() { 
43. SqlSession sqlSession = sqlSessionFactory.openSession(); 
44. try { 
45. User user = new User(); 
46. user.setId(1); 
47. user.setName("李四"); 
48. user.setAge(34); 
49. UserMapper userMapper = sqlSession.getMapper(UserMapper.class); 
50. userMapper.updateUser(user); 
51. sqlSession.commit(); 
52. } finally { 
53. sqlSession.close(); 
54. } 
55. } 
56. 
57. @Test
58. public void testFind() { 
59. SqlSession sqlSession = sqlSessionFactory.openSession(); 
60. try { 
61. UserMapper userMapper = sqlSession.getMapper(UserMapper.class); 
62. User user = userMapper.findById(1); 
63. System.out.println(user.getId() + "--" + user.getName() + "--" + user.getAge()); 
64. } finally { 
65. sqlSession.close(); 
66. } 
67. } 
68. 
69. @Test
70. public void testDelele() { 
71. SqlSession sqlSession = sqlSessionFactory.openSession(); 
72. try { 
73. UserMapper userMapper = sqlSession.getMapper(UserMapper.class); 
74. userMapper.deleteUser(5); 
75. sqlSession.commit(); 
76. } finally { 
77. sqlSession.close(); 
78. } 
79. } 
80. 
81. }