import java.util.List;
public class Blog {
private int id;
private String title;
private String content;
private String owner;

private List<Comment> comments;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public String getOwner() {
return owner;
}
public void setOwner(String owner) {
this.owner = owner;
}

public List<Comment> getComments() {
return comments;
}

public void setComments(List<Comment> comments) {
this.comments = comments;
}
@Override
public String toString() {
return " ----------------博客-----------------n id: " + id + "n title: " + title + "n content: " + content
+ "n owner: " + owner;
}
}

<typeAlias alias="Blog" type="com.tiantian.mybatis.model.Blog"/><!--来自MyBatis的配置文件mybatis_config.xml-->
<select id="selectBlog" parameterType="int" resultType="Blog">
select * from t_blog where id = #{id}
</select><!--来自SQL映射文件BlogMapper.xml-->

<resultMap type="Blog" id="BlogResult">
<id column="id" property="id"/>
<result column="title" property="title"/>
<result column="content" property="content"/>
<result column="owner" property="owner"/>
</resultMap>
<select id="selectBlog" parameterType="int" resultMap="BlogResult">
select * from t_blog where id = #{id}
</select>

import java.util.Date;
public class Comment {
private int id;
private String content;
private Date commentDate = new Date();
private Blog blog;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public Date getCommentDate() {
return commentDate;
}
public void setCommentDate(Date commentDate) {
this.commentDate = commentDate;
}
public Blog getBlog() {
return blog;
}
public void setBlog(Blog blog) {
this.blog = blog;
}
public String toString() {
return blog + "n ----------------评论-----------------n id: " + id + "n content: " + content + "n commentDate: " + commentDate;
}
}

<!--来自CommentMapper.xml文件 -->
<resultMap type="Comment" id="CommentResult">
<association property="blog" select="selectBlog" column="blog" javaType="Blog"/>
</resultMap>
<select id="selectComment" parameterType="int" resultMap="CommentResult">
select * from t_Comment where id = #{id}
</select>
<select id="selectBlog" parameterType="int" resultType="Blog">
select * from t_Blog where id = #{id}
</select>

<!-- 来自BlogMapper.xml文件 -->
<resultMap type="Blog" id="BlogResult">
<id column="id" property="id"/>
<collection property="comments" select="selectCommentsByBlog" column="id" ofType="Comment"></collection>
</resultMap>
<resultMap type="Comment" id="CommentResult">
<association property="blog" javaType="Blog" column="blog" select="selectBlog"/>
</resultMap>
<select id="selectBlog" parameterType="int" resultMap="BlogResult">
select * from t_blog where id = #{id}
</select>
<!-- 通过Blog来查找Comment -->
<select id="selectCommentsByBlog" parameterType="int" resultMap="CommentResult">
select * from t_Comment where blog = #{blogId}
</select>

@Test
public void selectCommentsByBlogTest() {
SqlSession session = Util.getSqlSessionFactory().openSession();
CommentMapper commentMapper = session.getMapper(CommentMapper.class);
List<Comment> comments = commentMapper.selectCommentsByBlog(6);
for (Comment comment : comments)
System.out.println(comment);
session.close();
}
/**
* 查询单条记录
*/
@Test
public void testSelectOne() {
SqlSession session = Util.getSqlSessionFactory().openSession();
BlogMapper blogMapper = session.getMapper(BlogMapper.class);
Blog blog = blogMapper.selectBlog(6);
List<Comment> comments = blog.getComments();
if (comments != null) {
System.out.println("--------------Comments Size------------" + comments.size());
for (Comment comment : comments)
System.out.println(comment);
}
session.close();
}