mybatis的xml映射文件，dao接口类，entity实体类

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/swjtu2014112194/article/details/85644786

xml映射文件的头文件：

<?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">

Book实体类（成员变量与数据库的一张表的属性一一对应）：

package com.cm.entity;

import java.util.Date;

import com.mysql.cj.xdevapi.Result;

/**
 * 图书实体
 */
public class Book {
    /**
     * 编号
     */
    private int id;
    /**
     * 书名
     */
    private String title;
    /**
     * 价格
     */
    private double price;
    /**
     * 出版日期
     */
    private Date publishDate;

    public Book(int id, String title, double price, Date publishDate) {
        this.id = id;
        this.title = title;
        this.price = price;
        this.publishDate = publishDate;
    }
    
    public Book() {
    }

    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 double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public Date getPublishDate() {
        return publishDate;
    }

    public void setPublishDate(Date publishDate) {
        this.publishDate = publishDate;
    }
    
    public String toString() {
    	String result = "id:" + id
    			+ " title:" + title
    			+ " price:" + price
    			+ " publishDate:" + publishDate;
    	return result;
    }
}

BookDAO接口（定义了对Book所对应的表的各种操作，但没有实现）:

package com.cm.dao;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import com.cm.entity.Book;



/**
 * 图书数据访问接口
 */
public interface BookDAO {
    /**
     * 获得所有图书
     */
    public List<Book> getAllBooks();
    /**
     * 根据图书编号获得图书对象
     */
    public Book getBookById(@Param("id") int id);
    /**
     * 添加图书
     */
    public int add(Book entity);
    /**
     * 根据图书编号删除图书
     */
    public int delete(int id);
    /**
     * 更新图书
     */
    public int update(Book entity);
}

BookMapper.xml实例（用sql语句实现dao接口的方法）：

<?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.cm.dao.BookDAO">
	<select id="getAllBooks" resultType="com.cm.entity.Book">
		select id, title, price, publishDate from books
	</select>
	<select id="getBookById">
		select id, title, price, publishDate from books where id=#{id}
	</select>
	<insert id="add">
        insert into books(title,price,publishDate)
        values(#{title},#{price},#{publishDate})
    </insert>
    <delete id="delete">
        delete from books where id=#{id}
    </delete>
    <update id="update">
        update books set title=#{title},price=#{price},publishDate=#{publishDate}
        where id=#{id}
    </update>
</mapper>

<mapper namespace = “dao接口完整的包名和接口名”>
<select>用于sql查询语句
<insert>用于sql新增语句
<update>用于sql更新语句
<delete>用于sql删除语句