轉自：http://blog.csdn.net/yulei_qq/article/details/22039815

工程的目錄結構：

有兩個表，一個文章表article ，一個用戶表user。

1. create table article (id int(11) not null auto_increment,
2. userid int(11) not null,
3. title varchar(100) not null,
4. content text not null,
5. primary key (id))ENGINE=InnoDB DEFAULT CHARSET=utf8;
7. insert into article(id,userid,title,content) values(1,1,‘test_title‘,‘text_content‘);
9. insert into article(id,userid,title,content) values(2,1,‘test_title_2‘,‘text_content_2‘);
10. insert into article(id,userid,title,content) values(3,1,‘test_title_3‘,‘text_content_3‘);
11. insert into article(id,userid,title,content) values(4,1,‘test_title_4‘,‘text_content_4‘);
14. create table user (id int(11) not null auto_increment,
15. userName varchar(50) default null,
16. userAge int(11) default null,
17. userAddress varchar(200) default null,
18. primary key(id)) ENGINE=InnoDB DEFAULT CHARSET=utf8;
21. insert into user(id,userName,userAge,userAddress) values(1,‘summer‘,‘100‘,‘上海‘);

現在要查詢,根據用戶的ID來查詢他所擁有的文章。那麽需要編寫SQL語句如下：

1. select a.id, a.userName ,a.userAddress ,b.id aid, b.title,b.content
2. from user a,article b
3. where a.id=b.userid and a.id=#{id}

現在就來貼下相關的JAVA代碼和映射文件吧,該說的都在註釋裏了。

User.java

1. package com.mybatis.model;
3. public class User {
4. private int id;
5. private String userName;
6. private String userAge;
7. private String userAddress;
9. public int getId() {
10. return id;
11. }
12. public void setId(int id) {
13. this.id = id;
14. }
15. public String getUserName() {
16. return userName;
17. }
18. public void setUserName(String userName) {
19. this.userName = userName;
20. }
21. public String getUserAge() {
22. return userAge;
23. }
24. public void setUserAge(String userAge) {
25. this.userAge = userAge;
26. }
27. public String getUserAddress() {
28. return userAddress;
29. }
30. public void setUserAddress(String userAddress) {
31. this.userAddress = userAddress;
32. }
34. }

Article.java

1. package com.mybatis.model;
3. public class Article {
5. private int id;
6. private User user; //文章的用戶定義一個User對象，而不是int 類型
7. private String title;
8. private String content;
10. public int getId() {
11. return id;
12. }
13. public void setId(int id) {
14. this.id = id;
15. }
16. public User getUser() {
17. return user;
18. }
19. public void setUser(User user) {
20. this.user = user;
21. }
22. public String getTitle() {
23. return title;
24. }
25. public void setTitle(String title) {
26. this.title = title;
27. }
28. public String getContent() {
29. return content;
30. }
31. public void setContent(String content) {
32. this.content = content;
33. }
35. }

接口類

IUserDao.java

1. package com.mybatis.dao;
3. import java.util.List;
4. import com.mybatis.model.Article;
6. public interface IUserDao {
8. public List<Article> getUserArticles(int id);
9. }

總配置文件configution.xml

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. <typeAliases>
7. <!-- 給實體類去一個別名 -->
8. <typeAlias type="com.mybatis.model.User" alias="User"/>
9. <typeAlias type="com.mybatis.model.Article" alias="Article"/>
10. </typeAliases>
12. <!-- 數據源配置，這裏用MySQL數據庫 -->
13. <environments default="development">
14. <environment id="development">
15. <transactionManager type="JDBC"/>
16. <dataSource type="POOLED">
17. <property name="driver" value="com.mysql.jdbc.Driver"/>
18. <property name="url" value="jdbc:mysql://127.0.0.1:3306/test"/>
19. <property name="username" value="root"/>
20. <property name="password" value="123456"/>
21. </dataSource>
22. </environment>
23. </environments>
25. <mappers>
26. <!-- book.xml裝載進來，等同於把Dao的實現類裝載進來 -->
27. <mapper resource="com/mybatis/model/User.xml"/>
28. </mappers>
30. </configuration>

User.xml

1. <?xml version="1.0" encoding="UTF-8" ?>
2. <!DOCTYPE mapper PUBLIC
3. "-//mybatis.org//DTD Mapper 3.0//EN"
4. "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
6. <mapper namespace="com.mybatis.dao.IUserDao">
7. <!-- User聯合Article進行查詢 (多對一的方式)-->
8. <resultMap type="Article" id="resultUserArticleList">
9. <id property="id" column="aid"/>
10. <result property="title" column="title"/>
11. <result property="content" column="content"/>
13. <!--關聯一個用戶 ,如果是關聯多個的話,就需要用collection了-->
14. <association property="user" javaType="User"> <!-- 這個 property="user" 對應的是Article中的User user屬性-->
15. <id property="id" column="id"/>
16. <result property="userName" column="userName"/>
17. <result property="userAddress" column="userAddress"/>
18. </association>
19. </resultMap>
21. <select id="getUserArticles" parameterType="int" resultMap="resultUserArticleList">
22. select a.id, a.userName ,a.userAddress ,b.id aid, b.title,b.content
23. from user a,article b
24. where a.id=b.userid and a.id=#{id}
25. </select>
26. </mapper>

總後，編寫個測試類.

1. package com.mybatis.test;
3. import java.io.IOException;
4. import java.util.List;
6. import org.apache.ibatis.io.Resources;
7. import org.apache.ibatis.session.SqlSession;
8. import org.apache.ibatis.session.SqlSessionFactory;
9. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
11. import com.mybatis.dao.IUserDao;
12. import com.mybatis.model.Article;
14. public class Test {
16. /***
17. * 獲得MyBatis SqlSessionFactory
18. * SqlSessionFactory 負責創建SqlSession ,一旦創建成功，就可以用SqlSession實例來執行映射語句
19. * ，commit,rollback,close等方法
20. * @return
21. */
22. private static SqlSessionFactory getSessionFactory(){
23. SqlSessionFactory sessionFactory=null;
24. String resource="configuration.xml";
25. try {
26. sessionFactory=new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource));
27. } catch (IOException e) {
28. e.printStackTrace();
29. }
30. return sessionFactory;
31. }
33. /**
34. * main 方法
35. * @param args
36. */
37. public static void main(String[] args) {
39. SqlSession session=getSessionFactory().openSession();
40. try {
41. IUserDao userDao=session.getMapper(IUserDao.class);
42. //傳入用戶的id=1
43. List<Article> listArticle=userDao.getUserArticles(1);
44. for(Article article:listArticle){
45. System.out.println(article.getTitle()+":"+article.getContent()+
46. ":作者是:"+article.getUser().getUserName()+":地址:"+
47. article.getUser().getUserAddress());
48. }
49. } catch (Exception e) {
50. e.printStackTrace();
51. }
53. finally{
54. session.close();
55. }
56. }
57. }

運行後結果如下：

1. test_title:text_content:作者是:summer:地址:上海
2. test_title_2:text_content_2:作者是:summer:地址:上海
3. test_title_3:text_content_3:作者是:summer:地址:上海
4. test_title_4:text_content_4:作者是:summer:地址:上海

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