MyBatis一对多映射简单查询案例（嵌套Mapper映射文件中的sql语句）

一、案例描述

书本类别表和书本信息表，查询书本类别表中的某一记录，连带查询出所有该类别书本的信息。

二、数据库表格

书本类别表（booktypeid,booktypename）

书本信息表（bookid,booktypeid,bookname...）

三、java代码

1.书本类别

BookType.java

package com.yh.entity;

import java.util.List;

public class BookType {

    private int bookTypeId;

    private String bookTypeName;

    private List<Book> books;

    public int getBookTypeId() {

        return bookTypeId;

    }

    public void setBookTypeId(int bookTypeId) {

        this.bookTypeId = bookTypeId;

    }

    public String getBookTypeName() {

        return bookTypeName;

    }

    public void setBookTypeName(String bookTypeName) {

        this.bookTypeName = bookTypeName;

    }

    public List<Book> getBooks() {

        return books;

    }

    public void setBooks(List<Book> books) {

        this.books = books;

    }

}

BookTypeMapper.xml

<!DOCTYPE mapper

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.yh.mybatis.mapper.BookTypeMapper">

    <select id="findTypeById" parameterType="int"

        resultMap="bookTypeMap">

        select *from booktype where booktypeid = #{id}

    </select>

    <resultMap type="BookType" id="bookTypeMap">

        <id property="bookTypeId" column="booktypeid"></id>

        <result property="bookTypeName" column="booktypename"></result>

        <collection property="books" column="booktypeid"

            select="com.yh.mybatis.mapper.BookMapper.findBookInfosByType" ofType="Book"></collection>

    </resultMap>

</mapper>

BookTypeMapper.java

package com.yh.mybatis.mapper;

import com.yh.entity.BookType;

public interface BookTypeMapper {

    BookType findTypeById(int id);

}

2.书本信息

Book.java（省略getter()、setter()方法）

package com.yh.entity;

import java.sql.Timestamp;

import java.sql.Date;

import com.yh.dao.DBAddRecord;

public class Book {

    // 自动赋值

    private int bookId;

    private int bookTypeId;

    private int sellerId;

    private String bookName;

    private String press;

    private Date publishDate;

    private short bookSize;

    private short bookVersion;

    private String author;

    private String translator;

    private String isbn;

    private float price;

    private int pageNumber;

    private String introduction;

    private float marketPrice;

    private float memberPrice;

}

BookMapper.xml

<!DOCTYPE mapper

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.yh.mybatis.mapper.BookMapper">

    <select id="findBookInfosByType" parameterType="int"

        resultType="Book">

        select bookname,dealamount,price,press,imgurl,bookid

        from book where booktypeid = #{id}

    </select>

</mapper>

BookMapper.java

package com.yh.mybatis.mapper;

import java.util.List;

import com.yh.entity.Book;

public interface BookMapper {

    List<Book> findBookInfosByType(String type);

}

3.测试代码

@ResponseBody

@RequestMapping(value="/byType",produces = "application/json; charset=utf-8")

public String byType(

        @RequestParam(value="type") String type){

    this.init();

    BookTypeMapper btm = sqlSession.getMapper(BookTypeMapper.class);

    BookType books = btm.findTypeById(Integer.valueOf(type));

    this.destroy();

    return JSON.toJSONString(books);

}

巴特西

MyBatis一对多映射简单查询案例（嵌套Mapper映射文件中的sql语句）

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