mybatis动态sql与分页

1. 动态sql

延续前篇博文，进行mybatis动态sql，自己书写方法进行测试
BookMapper类中新增方法

根据id查询

鼠标选中方法名按Alt+Enter键进行自动生成实现

 <select id="selectBooksIn" resultType="com.tanle.model.Book" parameterType="java.util.List">
    select * from t_mvc_book where bid in
    <foreach collection="bookIds" open="(" close=")" separator="," item="bid">
      #{bid}
    </foreach>
  </select>

去service实现 选中按Alt+Enter键实现生成

BookServiceImpl中通过bookMapper调取

测试类

模糊查询
在BookMapper书写以下三种方式查询

#{...}
${...}
Concat
注意：#{...}自带引号，${...}有sql注入的风险

三种不能的查询语句

再去BookService中调取 同样是Alt+Enter建生成

测试类

这里所使用的到的工具类StringUtils为了模糊查询拼接%%
第三种模糊查询方式不需要通过这个拼接 Concat

package com.tanle.util;

/**
 * @author tanle
 * @site www.tanle.com
 * @company xxx公司
 * @create  2020-10-15 18:24
 */
public class StringUtils {
    public static String toLinkeStr(String str){
        return "%"+str+"%";
    }
}

查询返回结果集的处理
resultMap：适合使用返回值是自定义实体类的情况
resultType：适合使用返回值的数据类型是非自定义的，即jdk的提供的类型

使用resultMap返回自定义类型集合
使用resultType返回List
使用resultType返回单个对象
使用resultType返回List

书写一个BookVo实体类
mybatis hibernate都是orm框架，表所存在的列段在实体类model都有映射
实际开发中，会因为某一些需求改变model 破坏model的封装性
此时为了保证Model的封装性，就可以使用vo类来完成指定的需求

package com.tanle.model.vo;

import com.tanle.model.Book;

import java.util.List;

/**
 * @author tanle
 * @site www.tanle.com
 * @company xxx公司
 * @create  2020-10-15 18:40
 *
 *
 * vo介绍
 * mybatis hibernate都是orm框架，表所存在的列段在实体类model都有映射
 * 实际开发中，会因为某一些需求改变model 破坏model的封装性
 * 此时为了保证Model的封装性，就可以使用vo类来完成指定的需求
 *
 */
public class BookVo extends Book {
    private Integer min;
    private Integer max;
    private List<Integer> bookIds;

    public Integer getMin() {
        return min;
    }

    public void setMin(Integer min) {
        this.min = min;
    }

    public Integer getMax() {
        return max;
    }

    public void setMax(Integer max) {
        this.max = max;
    }

    public List<Integer> getBookIds() {
        return bookIds;
    }

    public void setBookIds(List<Integer> bookIds) {
        this.bookIds = bookIds;
    }
}

service

2. 分页查询

为什么要重写mybatis的分页？
Mybatis的分页功能很弱，它是基于内存的分页(查出所有记录再按偏移量offset和边界limit取结果)，在大数据量的情况下这样的分页基本上是没有用的

使用分页插件步奏
1、导入pom依赖

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper</artifactId>
    <version>5.1.2</version>
</dependency>

2、Mybatis.cfg.xml配置拦截器

<plugins>
    <!-- 配置分页插件PageHelper, 4.0.0以后的版本支持自动识别使用的数据库 -->
    <plugin interceptor="com.github.pagehelper.PageInterceptor">
    </plugin>
</plugins>

3、使用PageHelper进行分页

<select id="listPager" resultType="java.util.Map" parameterType="java.util.Map">
  select * from t_mvc_book where bname like concat(concat('%',#{bname}),'%')
</select>

Mapper层

List<Map> listPager(Map map);

Service层

List<Map> listPager(Map map, PageBean pageBean);

BookServiceImpl实现层

@Override
public List<Map> listPager(Map map, PageBean pageBean) {
    if(pageBean != null && pageBean.isPagination()){
        PageHelper.startPage(pageBean.getPage(),pageBean.getRows());
    }
    List<Map> list = bookMapper.listPager(map);
    if(pageBean != null && pageBean.isPagination()){
        PageInfo pageInfo = new PageInfo(list);
        System.out.println("页码："+pageInfo.getPageNum());
        System.out.println("页大小："+pageInfo.getPageSize());
        System.out.println("总记录："+pageInfo.getTotal());
        pageBean.setTotal(pageInfo.getTotal()+"");
    }
    return list;
}

PageBean工具类

package com.tanle.util;

import java.io.Serializable;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;

public class PageBean implements Serializable {

	private static final long serialVersionUID = 2422581023658455731L;

	//页码
	private int page=1;
	//每页显示记录数
	private int rows=10;
	//总记录数
	private int total=0;
	//是否分页
	private boolean isPagination=true;
	//上一次的请求路径
	private String url;
	//获取所有的请求参数
	private Map<String,String[]> map;
	
	public PageBean() {
		super();
	}
	
	//设置请求参数
	public void setRequest(HttpServletRequest req) {
		String page=req.getParameter("page");
		String rows=req.getParameter("rows");
		String pagination=req.getParameter("pagination");
		this.setPage(page);
		this.setRows(rows);
		this.setPagination(pagination);
		this.url=req.getContextPath()+req.getServletPath();
		this.map=req.getParameterMap();
	}
	public String getUrl() {
		return url;
	}

	public void setUrl(String url) {
		this.url = url;
	}

	public Map<String, String[]> getMap() {
		return map;
	}

	public void setMap(Map<String, String[]> map) {
		this.map = map;
	}

	public int getPage() {
		return page;
	}

	public void setPage(int page) {
		this.page = page;
	}
	
	public void setPage(String page) {
		if(null!=page&&!"".equals(page.trim()))
			this.page = Integer.parseInt(page);
	}

	public int getRows() {
		return rows;
	}

	public void setRows(int rows) {
		this.rows = rows;
	}
	
	public void setRows(String rows) {
		if(null!=rows&&!"".equals(rows.trim()))
			this.rows = Integer.parseInt(rows);
	}

	public int getTotal() {
		return total;
	}

	public void setTotal(int total) {
		this.total = total;
	}
	
	public void setTotal(String total) {
		this.total = Integer.parseInt(total);
	}

	public boolean isPagination() {
		return isPagination;
	}
	
	public void setPagination(boolean isPagination) {
		this.isPagination = isPagination;
	}
	
	public void setPagination(String isPagination) {
		if(null!=isPagination&&!"".equals(isPagination.trim()))
			this.isPagination = Boolean.parseBoolean(isPagination);
	}
	
	/**
	 * 获取分页起始标记位置
	 * @return
	 */
	public int getStartIndex() {
		//(当前页码-1)*显示记录数
		return (this.getPage()-1)*this.rows;
	}
	
	/**
	 * 末页
	 * @return
	 */
	public int getMaxPage() {
		int totalpage=this.total/this.rows;
		if(this.total%this.rows!=0)
			totalpage++;
		return totalpage;
	}
	
	/**
	 * 下一页
	 * @return
	 */
	public int getNextPage() {
		int nextPage=this.page+1;
		if(this.page>=this.getMaxPage())
			nextPage=this.getMaxPage();
		return nextPage;
	}
	
	/**
	 * 上一页
	 * @return
	 */
	public int getPreivousPage() {
		int previousPage=this.page-1;
		if(previousPage<1)
			previousPage=1;
		return previousPage;
	}

	@Override
	public String toString() {
		return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", isPagination=" + isPagination
				+ "]";
	}
}

4、处理分页结果

 @Test
    public void listPager() {
        Map map=new HashMap();
        map.put("bname","%圣墟%");
        PageBean pageBean=new PageBean();
        //不分页
        //pageBean.setPagination(false);
        //第二页
        pageBean.setPage(2);
        List<Map> maps = this.bookService.listPager(map, pageBean);
        for (Map map1 : maps) {
            System.out.println(map1);
        }
    }

3. 特殊字符处理

>(>)   
<(&lt;)  
&(&amp;) 
空格(&nbsp;)
<![CDATA[ <= ]]> 

4. 代码块

BookServiceTest 测试类代码块

package com.tanle.service;

import com.sun.javafx.collections.MappingChange;
import com.tanle.mapper.BookMapper;
import com.tanle.model.Book;
import com.tanle.model.vo.BookVo;
import com.tanle.service.impl.BookServiceImpl;
import com.tanle.util.PageBean;
import com.tanle.util.SessionUtil;
import com.tanle.util.StringUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import static org.junit.Assert.*;

/**
 * @author tanle
 * @site www.tanle.com
 * @company xxx公司
 * @create  2020-10-13 15:57
 */
public class BookServiceTest {
    //测试bookService接口是否有用
    //先测试不为空
    private BookService bookService;
    private SqlSession sqlSession;

    @Before
    public void setUp() throws Exception {
        BookServiceImpl bookServiceImpl = new BookServiceImpl();
        sqlSession = SessionUtil.openSession();
        bookServiceImpl.setBookMapper(sqlSession.getMapper(BookMapper.class));
        this.bookService = bookServiceImpl;
    }

    @After
    public void tearDown() throws Exception {
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void insert() {
        Book book = new Book();
        book.setBname("mybatis插入");
        book.setPrice(99f);
        int insert = bookService.insert(book);
        System.out.println(insert);
    }

    @Test
    public void selectByPrimaryKey() {
        Book book = bookService.selectByPrimaryKey(27);
        System.out.println(book.toString());
    }

    @Test
    public void selectBooksIn() {
        List list=new ArrayList();
        list.add(19);
        list.add(18);
        list.add(99);
        List<Book> books = this.bookService.selectBooksIn(list);
        for (Book book : books) {
            System.out.println(book);
        }
    }

    /*
    * #和$的区别
    * #号相当于单引号拼接执行sql
    *  select * from t_mvc_book where bname like '%圣墟%'
    * $会引起sql攻击
    * */
    @Test
    public void selectBooksI1() {
        String bname="圣墟";
        //第一种根据工具类拼接%进行模糊查询
        List<Book> books = this.bookService.selectBooksIn1(StringUtils.toLinkeStr(bname));
        //List<Book> books = this.bookService.selectBooksIn2(StringUtils.toLinkeStr(bname));
        //List<Book> books = this.bookService.selectBooksIn3(bname);
        for (Book book : books) {
            System.out.println(book);
        }
    }

    @Test
    public void list() {
       // List<Book> books = this.bookService.list1();
       // List<Book> books = this.bookService.list2();
        List list=new ArrayList();
        list.add(15);
        list.add(18);
        list.add(99);
       /* BookVo bookVo=new BookVo();
        bookVo.setBookIds(list);
        List<Book> books = this.bookService.list3(bookVo);*/
       /* for (Book book : books) {
            System.out.println(book);
        }*/

        Map map=new HashMap();
        /*map.put("bookIds",list);
        List<Map> books = this.bookService.list4(map);
        for (Map book : books) {
            System.out.println(book);
        }*/
        map.put("bid",19);
        Map map1 = this.bookService.list5(map);
        System.out.println(map1);
    }

    @Test
    public void listPager() {
        Map map=new HashMap();
        map.put("bname","%圣墟%");
        PageBean pageBean=new PageBean();
        //不分页
        //pageBean.setPagination(false);
        //第二页
        pageBean.setPage(2);
        List<Map> maps = this.bookService.listPager(map, pageBean);
        for (Map map1 : maps) {
            System.out.println(map1);
        }
    }
    @Test
    public void list6() {
        BookVo bookVo=new BookVo();
        bookVo.setMin(2);
        bookVo.setMax(20);
        List<Book> books = bookService.list6(bookVo);
        for (Book book : books) {
            System.out.println(book);
        }
    }

}

BookMapper

package com.tanle.mapper;

import com.tanle.model.Book;
import com.tanle.model.vo.BookVo;
import com.tanle.util.PageBean;
import org.apache.ibatis.annotations.Param;

import java.util.List;
import java.util.Map;

public interface BookMapper {
    int deleteByPrimaryKey(Integer bid);

    int insert(Book record);

    int insertSelective(Book record);

    Book selectByPrimaryKey(Integer bid);

    int updateByPrimaryKeySelective(Book record);

    int updateByPrimaryKey(Book record);

    /*
    * Param
    * 如果形参要在mapper.xml中使用就需要加上面注解
    * map name:zs age:12
    * @param bookIds
    *
    * */
    List<Book> selectBooksIn(@Param("bookIds") List bookIds);

    List<Book> selectBooksIn1(@Param("bname") String bname);
    List<Book> selectBooksIn2(@Param("bname") String bname);
    List<Book> selectBooksIn3(@Param("bname") String bname);


    /*
    * mybatis结果集处理的五种情况
    * */
    List<Book> list1();
    List<Book> list2();
    List<Book> list3(BookVo bookVo);
    List<Map> list4(Map map);
    Map list5(Map map);

    /*、
    * 分页
    * */
    List<Map> listPager(Map map);

    /*
    * mybatis特殊字符处理
    * 第一种写法
    *  select * from t_mvc_book where price &gt;#{min} and price &lt;#{max}
    *  第二种包含
    *      select * from t_mvc_book where  <![CDATA[ price > #{min} and price < #{max}]]>
    * * */
    List<Book> list6(BookVo bookVo);

}

BookMapper.xml

<?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.tanle.mapper.BookMapper" >
  <resultMap id="BaseResultMap" type="com.tanle.model.Book" >
    <constructor >
      <idArg column="bid" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="bname" jdbcType="VARCHAR" javaType="java.lang.String" />
      <arg column="price" jdbcType="REAL" javaType="java.lang.Float" />
    </constructor>
  </resultMap>
  <sql id="Base_Column_List" >
    bid, bname, price
  </sql>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from t_mvc_book
    where bid = #{bid,jdbcType=INTEGER}
  </select>

  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from t_mvc_book
    where bid = #{bid,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.tanle.model.Book" >
    insert into t_mvc_book (bid, bname, price
      )
    values (#{bid,jdbcType=INTEGER}, #{bname,jdbcType=VARCHAR}, #{price,jdbcType=REAL}
      )
  </insert>
  <insert id="insertSelective" parameterType="com.tanle.model.Book" >
    insert into t_mvc_book
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="bid != null" >
        bid,
      </if>
      <if test="bname != null" >
        bname,
      </if>
      <if test="price != null" >
        price,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="bid != null" >
        #{bid,jdbcType=INTEGER},
      </if>
      <if test="bname != null" >
        #{bname,jdbcType=VARCHAR},
      </if>
      <if test="price != null" >
        #{price,jdbcType=REAL},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.tanle.model.Book" >
    update t_mvc_book
    <set >
      <if test="bname != null" >
        bname = #{bname,jdbcType=VARCHAR},
      </if>
      <if test="price != null" >
        price = #{price,jdbcType=REAL},
      </if>
    </set>
    where bid = #{bid,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.tanle.model.Book" >
    update t_mvc_book
    set bname = #{bname,jdbcType=VARCHAR},
      price = #{price,jdbcType=REAL}
    where bid = #{bid,jdbcType=INTEGER}
  </update>

  <!--
    Foreach
    resultType 返回对象
    parameterType 返回参数
    collection 接收传过来的变量
    item 取名
  -->
  <select id="selectBooksIn" resultType="com.tanle.model.Book" parameterType="java.util.List">
    select * from t_mvc_book where bid in
    <foreach collection="bookIds" open="(" close=")" separator="," item="bid">
      #{bid}
    </foreach>
  </select>


  <select id="selectBooksIn1" resultType="com.tanle.model.Book" parameterType="java.lang.String">
    select * from t_mvc_book where bname like #{bname}
  </select>
  <select id="selectBooksIn2" resultType="com.tanle.model.Book" parameterType="java.lang.String">
    select * from t_mvc_book where bname like '${bname}'
  </select>
  <select id="selectBooksIn3" resultType="com.tanle.model.Book" parameterType="java.lang.String">
    select * from t_mvc_book where bname like concat(concat('%',#{bname}),'%')
  </select>


  <select id="list1" resultMap="BaseResultMap">
    select  * from t_mvc_book
  </select>
  <select id="list2" resultType="com.tanle.model.Book">
    select  * from t_mvc_book
  </select>
  <select id="list3" resultType="com.tanle.model.Book" parameterType="com.tanle.model.vo.BookVo">
    select * from t_mvc_book where bid in
    <foreach collection="bookIds" open="(" close=")" separator="," item="bid">
      #{bid}
    </foreach>
  </select>
  <select id="list4" resultType="java.util.Map" parameterType="java.util.Map">
    select * from t_mvc_book where bid in
    <foreach collection="bookIds" open="(" close=")" separator="," item="bid">
      #{bid}
    </foreach>
  </select>
  <select id="list5" resultType="java.util.Map" parameterType="java.util.Map">
    select * from t_mvc_book where bid = #{bid}
  </select>

  <select id="listPager" resultType="java.util.Map" parameterType="java.util.Map">
    select * from t_mvc_book where bname like concat(concat('%',#{bname}),'%')
  </select>
  <select id="list6" resultType="com.tanle.model.Book" parameterType="com.tanle.model.vo.BookVo">
    select * from t_mvc_book where  <![CDATA[ price > #{min} and price < #{max}]]>
  </select>


</mapper>

BookServiceImpl

package com.tanle.service.impl;

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.tanle.mapper.BookMapper;
import com.tanle.model.Book;
import com.tanle.model.vo.BookVo;
import com.tanle.service.BookService;
import com.tanle.util.PageBean;

import java.util.List;
import java.util.Map;

/**
 * @author tanle
 * @site www.tanle.com
 * @company xxx公司
 * @create  2020-10-13 14:11
 */
public class BookServiceImpl implements BookService {
    //依赖于Bookmapper
    private BookMapper bookMapper;

    public BookMapper getBookMapper() {
        return bookMapper;
    }

    public void setBookMapper(BookMapper bookMapper) {
        this.bookMapper = bookMapper;
    }

    public int deleteByPrimaryKey(Integer bid) {
        return bookMapper.deleteByPrimaryKey(bid);
    }

    public int insert(Book record) {
        return bookMapper.insert(record);
    }

    public int insertSelective(Book record) {
        return bookMapper.insertSelective(record);
    }

    public Book selectByPrimaryKey(Integer bid) {
        return bookMapper.selectByPrimaryKey(bid);
    }

    public int updateByPrimaryKeySelective(Book record) {
        return bookMapper.updateByPrimaryKeySelective(record);
    }

    public int updateByPrimaryKey(Book record) {
        return bookMapper.updateByPrimaryKey(record);
    }

    @Override
    public List<Book> selectBooksIn(List bookIds) {
        return bookMapper.selectBooksIn(bookIds);
    }

    @Override
    public List<Book> selectBooksIn1(String bname) {

        return bookMapper.selectBooksIn1(bname);
    }

    @Override
    public List<Book> selectBooksIn2(String bname) {
        return bookMapper.selectBooksIn2(bname);
    }

    @Override
    public List<Book> selectBooksIn3(String bname) {
        return bookMapper.selectBooksIn3(bname);
    }

    @Override
    public List<Book> list1() {
        return bookMapper.list1();
    }

    @Override
    public List<Book> list2() {
        return bookMapper.list2();
    }

    @Override
    public List<Book> list3(BookVo bookVo) {
        return bookMapper.list3(bookVo);
    }

    @Override
    public List<Map> list4(Map map) {
        return bookMapper.list4(map);
    }

    @Override
    public Map list5(Map map) {
        return bookMapper.list5(map);
    }

    @Override
    public List<Map> listPager(Map map, PageBean pageBean) {
        if(pageBean != null && pageBean.isPagination()){
            PageHelper.startPage(pageBean.getPage(),pageBean.getRows());
        }
        List<Map> maps = bookMapper.listPager(map);
        if(pageBean != null && pageBean.isPagination()){
            PageInfo pageInfo=new PageInfo(maps);
            System.out.println("总记录数："+pageInfo.getTotal());
            System.out.println("当前页："+pageInfo.getPageNum());
            System.out.println("页大小："+pageInfo.getPageSize());
            pageBean.setTotal(pageInfo.getTotal()+"");
            System.out.println("总页数："+pageBean.getMaxPage());
        }
        return maps;
    }

    @Override
    public List<Book> list6(BookVo bookVo) {
        return bookMapper.list6(bookVo);
    }
}