mybatis学习(47):嵌套查询--一对一

数据库

 

 

 

 

目录结构

 

 

映入jar包和junit单元测试

com.geyao.mybatis.mapper

AuthorMapper类
 

package com.geyao.mybatis.mapper;
 
import com.geyao.mybatis.pojo.Author;
public interface AuthorMapper {
    Author selectAuthorById(Integer id);
}
BlogMapper类

package com.geyao.mybatis.mapper;
 
 
import com.geyao.mybatis.pojo.Blog;
 
public interface BlogMapper {
    Blog selectBlogById(Integer id);
}
AuthorMapper.xml

   
   
 
   
   
   select * from author where id=#{id}
   

BlogMapper.xml

   
                                        
             select="com.geyao.mybatis.mapper.AuthorMapper.selectAuthorById">
   
   
   
   
   select * from Blog where id=#{id}
   

com.geyao.mybatis.pojo

Author类

package com.geyao.mybatis.pojo;
 
public class Author {
    private Integer id;
    private String username;
    private String password;
    private String email;
    private String bio;
    private String favouriteSection;
    private String nickname;
    private String realname;
    public Author() {
        super();
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getBio() {
        return bio;
    }
    public void setBio(String bio) {
        this.bio = bio;
    }
    public String getFavouriteSection() {
        return favouriteSection;
    }
    public void setFavouriteSection(String favouriteSection) {
        this.favouriteSection = favouriteSection;
    }
    public String getNickname() {
        return nickname;
    }
    public void setNickname(String nickname) {
        this.nickname = nickname;
    }
    public String getRealname() {
        return realname;
    }
    public void setRealname(String realname) {
        this.realname = realname;
    }
    public Author(Integer id, String username, String password, String email, String bio, String favouriteSection,
            String nickname, String realname) {
        super();
        this.id = id;
        this.username = username;
        this.password = password;
        this.email = email;
        this.bio = bio;
        this.favouriteSection = favouriteSection;
        this.nickname = nickname;
        this.realname = realname;
    }
    @Override
    public String toString() {
        return "Author [id=" + id + ", username=" + username + ", password=" + password + ", email=" + email + ", bio="
                + bio + ", favouriteSection=" + favouriteSection + ", nickname=" + nickname + ", realname=" + realname
                + "]";
    }
    
    
    
}
Blog类

package com.geyao.mybatis.pojo;
 
import java.io.Serializable;
 
public class Blog implements Serializable {
 
    private static final long serialVersionUID = 1L;
    private Integer id;
    private String title;
    private Author author;
    private String state;
    private boolean featured;
    private String style;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public Author getAuthor() {
        return author;
    }
    public void setAuthor(Author author) {
        this.author = author;
    }
    public String getState() {
        return state;
    }
    public void setState(String state) {
        this.state = state;
    }
    public boolean isFeatured() {
        return featured;
    }
    public void setFeatured(boolean featured) {
        this.featured = featured;
    }
    public String getStyle() {
        return style;
    }
    public void setStyle(String style) {
        this.style = style;
    }
    public static long getSerialversionuid() {
        return serialVersionUID;
    }
    @Override
    public String toString() {
        return "Blog [id=" + id + ", title=" + title + ", author=" + author + ", state=" + state + ", featured="
                + featured + ", style=" + style + "]";
    }
    
    
    
 
}
com.geyao.mybatis.util

MybatisUtil类

package com.geyao.mybatis.util;
 
import java.io.InputStream;
import java.io.Reader;
 
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 
public class MyBatisUtil {
    private static SqlSessionFactory sqlSessionFactory =null;
    static {
        try {
            InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    private MyBatisUtil() {}
    
    public static SqlSession getSqlSession() {
        return sqlSessionFactory.openSession();
    }
}
com.geyao.mybatis.mapper测试类

BlogMapperTest

package com.geyao.mybatis.mapper;
 
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
 
import com.geyao.mybatis.pojo.Author;
import com.geyao.mybatis.pojo.Blog;
import com.geyao.mybatis.util.MyBatisUtil;
 
public class BlogMapperTest {
    @Test
    public void testSelectBlog() {
        SqlSession session =MyBatisUtil.getSqlSession();
        BlogMapper blogMapper =session.getMapper(BlogMapper.class);
        
        Blog blog = blogMapper.selectBlogById(1);
        session.close();
        System.out.println(blog);
    }
    
 
}

mybatis-config.xml

    


    
    

   
       
           
           
           
               
               
               
               
           
       
   
     
       
         
         
     

log4j.properties

### \u914D\u7F6E\u6839 ###
log4j.rootLogger = debug,console ,fileAppender,dailyRollingFile,ROLLING_FILE,MAIL,DATABASE
 
### \u8BBE\u7F6E\u8F93\u51FAsql\u7684\u7EA7\u522B\uFF0C\u5176\u4E2Dlogger\u540E\u9762\u7684\u5185\u5BB9\u5168\u90E8\u4E3Ajar\u5305\u4E2D\u6240\u5305\u542B\u7684\u5305\u540D ###
log4j.logger.org.apache=dubug
log4j.logger.java.sql.Connection=dubug
log4j.logger.java.sql.Statement=dubug
log4j.logger.java.sql.PreparedStatement=dubug
log4j.logger.java.sql.ResultSet=dubug
 
### \u914D\u7F6E\u8F93\u51FA\u5230\u63A7\u5236\u53F0 ###
log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.Target = System.out
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern =  %d{ABSOLUTE} %5p %c{1}:%L - %m%n
运行结果