mybatis动态SQL以及分页模糊查询和返回结果集处理

1. mybatis动态sql

BookMapper

List<Book> selectByIn(@Param("bookIds") List bookIds);


    /*模糊查询的方式*/
    List<Book> selectBylike1(@Param("bname") String bname);

    List<Book> selectBylike2(@Param("bname") String bname);

    List<Book> selectBylike3(@Param("bname") String bname);

//     3.1 使用r esultMap返回自定义类型集合
    List<Book> list1();


//    3.2 使用resultType返回List

    List<Book> list2();

//    3.3 使用resultType返回单个对象
    Book list3(BookVo bookVo);


//    3.4 使用resultType返回List
    List<Map> list4(Map map);

//3.5 使用resultType返回Map，适用于多表查询返回单个结果集
    Map list5(Map map);


//处理特殊字符的方式
    List<Map> list6(BookVo bookVo);

    List<Map> list7(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.lin.mapper.BookMapper" >
<!--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-->
<!--下面会使用到这个BaseResultMap-->

  <resultMap id="BaseResultMap" type="com.lin.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.lin.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.lin.model.Book" >
    insert into t_mvc_book
    <trim prefix="(" suffix=")" suffixOverrides="," >
 <!--  trim:一样的sql语句拼接：prefix前缀，suffi 后缀。suffixOverrides 后缀覆盖-->
      <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.lin.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.lin.model.Book" >
    update t_mvc_book
    set bname = #{bname,jdbcType=VARCHAR},
      price = #{price,jdbcType=REAL}
    where bid = #{bid,jdbcType=INTEGER}
  </update>


  <!--自己写的-->
  <select id="selectByIn" resultType="com.lin.model.Book" parameterType="java.util.List">
    select * from t_mvc_book where bid in 
   <!-- foreach 就是循环的意思，collection代表要被循环参数集合。
   open和close代表开始和结束拼接字符串。separator代表item之间的分割符。
   item就是当前正在循环的变量定义。就当java中的foreach看就能看懂了-->
    <foreach collection="bookIds" open="(" close=")" separator="," item="bid">
        #{bid}
    </foreach>
  </select>

  <!--模糊查的三种方式-->
  <!--注意：#{…}自带引号，${…}有sql注入的风险-->
  
  <!--推荐使用这种-->
  <select id="selectBylike1" resultType="com.lin.model.Book" parameterType="java.lang.String">
    select * from t_mvc_book where bname like #{bname}
  </select>
 <!--此方式不会自动加 双引号，存在sql注入的风险-->
  <select id="selectBylike2" resultType="com.lin.model.Book" parameterType="java.lang.String">
    select * from t_mvc_book where bname like '${bname}'
  </select>

 <!--这种方式也能实现，不过比较麻烦，一般每谁去使用 -->
  <select id="selectBylike3" resultType=com.lin.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.lin.model.Book">
    select * from t_mvc_book

  </select>
  <select id="list3" resultType="com.lin.model.Book" parameterType="com.lin.model.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" parameterMap="java.util.Map">
     select * from t_mvc_book
     <where>
     
     <!--如果 test 不为空，就进行if体的拼接-->
       <if test="null != bname and bname!=''" >
         and bname like #{bname} <! -- 这就是if体 -->
       </if>
     </where>
  </select>

  <select id="list5" resultType="java.util.Map" parameterMap="java.util.Map">
    select * from t_mvc_book
    <where>
      <!--如果 test 不为空，就进行if体的拼接-->
      <if test="null != bid and bid!=''" >
        and bid = #{bid}<! -- 这就是if体 -->
      </if>
    </where>
  </select>
  <select id="list6" resultType="java.util.Map" parameterType="com.lin.model.BookVo">
    select * from t_mvc_book
    <where>
      <if test="null != min and min != ''">
        <![CDATA[  and #{min} < price ]]>
      </if>
      <if test="null != max and max != ''">
        <![CDATA[ and #{max} > price ]]>
      </if>
    </where>
  </select>
  <select id="list7" resultType="java.util.Map" parameterType="com.lin.model.BookVo">
    select * from t_mvc_book
    <where>
      <if test="null != min and min != ''">
        and #{min} &lt; price
      </if>
      <if test="null != max and max != ''">
        and #{max} &gt; price
      </if>
    </where>
  </select>

</mapper>

2. 分页模糊查询和返回结果集处理

Pom依赖

• 动态sql、结果集处理和特殊字符处理上面注释写的都很清楚了，后面主要提一下分页的插件
• 导入分页插件pom

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

Mybatis.cfg.xml配置拦截器

• 将pagehelper插件配置到mybatis中,注意要配在运行环境之前

   <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>

BookService

package com.lin.service;

import com.lin.model.Book;
import com.lin.model.BookVo;
import com.lin.util.PageBean;

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


/**
 * @authorlinfan
 * @site www.linfanmage.com
 * @company xxx公司
 * @create  2019-09-20 18:17
 */
public interface BookService {
    int deleteByPrimaryKey(Integer bid);

    int insert(Book record);

    int insertSelective(Book record);

    Book selectByPrimaryKey(Integer bid);

    int updateByPrimaryKeySelective(Book record);

    int updateByPrimaryKey(Book record);

    List<Book> selectByIn( List bookIds);

    /*模糊查*/
    List<Book> selectBylike1(String bname);
    List<Book> selectBylike2(String bname);
    List<Book> selectBylike3(String bname);

    /*使用resultMap返回自定义类型集合*/
    List<Book> list1();
    
    /*使用resultType返回List*/
    List<Book> list2();
    
    /*使用resultType返回单个对象*/
    Book list3(BookVo bookVo);
 
   /* 使用resultType返回List适用于多表查询返回结果集*/
    List<Map> list4(Map map);

   /* 使用resultType返回Map适用于多表查询返回单个结果集*/
    Map list5(Map book);

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

    /*特殊字符处理*/
    List<Map> list6(BookVo bookVo);
    List<Map> list7(BookVo bookVo);


}

BookServiceImpl

package com.lin.service.impl;

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

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

/**
 * @authorlinfan
 * @site www.linfanmage.com
 * @company xxx公司
 * @create  2019-09-20 18:17
 */
public class BookServiceImpl implements BookService {
    private BookMapper bookMapper;

    public BookMapper getBookMapper() {
        return bookMapper;
    }

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

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

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

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

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

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

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

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

    @Override
    public List<Book> selectBylike1(String bname) {
        return bookMapper.selectBylike1(bname);
    }

    @Override
    public List<Book> selectBylike2(String bname) {
        return bookMapper.selectBylike2(bname);
    }

    @Override
    public List<Book> selectBylike3(String bname) {
        return bookMapper.selectBylike3(bname);
    }

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

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

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

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

    @Override
    public Map list5(Map book) {
        return bookMapper.list5(book);
    }
    
	//在业务逻辑成中写一个 listPager 的分页方法
    @Override
    public List<Map> listPager(Map map, PageBean pageBean) {
    //如果分页对象不为空就继续分页操作
        if(pageBean != null && pageBean.isPagination()){
            PageHelper.startPage(pageBean.getPage(),pageBean.getRows());
        }

        List<Map> list = this.bookMapper.list4(map);
        if(pageBean != null && pageBean.isPagination()){
        //如果分页对象不为空，就输出分页后的结果信息
            PageInfo pageInfo=new PageInfo(list);
            System.out.println("当前的页码："+pageInfo.getPageNum());
            System.out.println("页数据量："+pageInfo.getSize());
            System.out.println("总记录数:"+pageInfo.getTotal());
            pageBean.setTotal(pageInfo.getTotal()+"");
        }
        return list;
    }

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

    @Override
    public List<Map> list7(BookVo bookVo) {
        return bookMapper.list7(bookVo);
    }
}

PageBean

package com.lin.util;

import javax.servlet.http.HttpServletRequest;
import java.io.Serializable;
import java.util.Map;

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
				+ "]";
	}
}

StringUtils

package com.lin.util;

/**
 * @authorlinfan
 * @site www.linfanmage.com
 * @company xxx公司
 * @create  2019-09-20 18:17
 */
public class StringUtils {
    public static String toLikeStr(String str){
        return "%"+str+"%";
    }
}

BookVo

• vo类，就是value Object，用来处理查询条件所需要用到的而又不是数据库字段的属性
• 用来存放包括数据库表映射字段以及多余查询条件所用到的属性

package com.lin.model;

import java.util.List;

/**
 * @authorlinfan
 * @site www.linfanmage.com
 * @company xxx公司
 * @create  2019-09-20 18:17
 * vo用来存放包裹数据库表映射字段以及多余查询条件所需属性
 */
public class BookVo {
    private List<String> bookIds;
    private float min;
    private float max;

    public float getMin() {
        return min;
    }

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

    public float getMax() {
        return max;
    }

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

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

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


}

JUnit测试代码

package com.lin.test;

import com.lin.mapper.BookMapper;
import com.lin.model.Book;
import com.lin.model.BookVo;
import com.lin.service.BookService;
import com.lin.service.impl.BookServiceImpl;
import com.lin.util.PageBean;
import com.lin.util.SessionUtil;
import com.lin.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;


/**
 * @author 小李飞刀
 * @site www.javaxl.com
 * @company
 * @create  2019-09-19 15:35
 */
public class MapperSqlTest {
    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 selectByIn() {
        List list=new ArrayList();
        list.add(2);
        list.add(5);
        list.add(27);
        list.add(19);
        List<Book> books = this.bookService.selectByIn(list);
        for (Book book : books) {
            System.out.println(book);
        }
    }

    /**
     * 模糊查
     */
    @Test
    public void selectBylike() {
//        List books = this.bookService.selectBylike1("%圣墟%");
//        List books = this.bookService.selectBylike1(StringUtils.toLikeStr("圣墟"));
            /*${}需要在外面加引号，存在sql攻击的可能*/
//        List books = this.bookService.selectBylike2("%圣墟%");
        List<Book> books = this.bookService.selectBylike3("圣墟");
        for (Book book : books) {
            System.out.println(book);
        }
    }

    /**
     * 结果集处理
     */
    @Test
    public void list() {
        /*1、返回一个resultMap但是使用list*/
//        List books = this.bookService.list1();
        /*2、返回的是resulttype使用list接收*/
//        List books = this.bookService.list2();
//        for (Book b : books) {
//            System.out.println(b);
//        }

       /*3、返回的是resulttype使用T接收*/
//        BookVo bookVo=new BookVo();
//        List list=new ArrayList();
//        list.add(27);
//        bookVo.setBookIds(list);
//        Book book = this.bookService.list3(bookVo);
//        System.out.println(book);
//
        /*4、返回的是resulttype，然后用List
        Map map=new HashMap<>();
//        map.put("bname", StringUtils.toLikeStr("圣墟"));
//        List
//        for (Map m : list) {
//            System.out.println(m);
//        }

        /*5、返回的是resultType,然后用List
        map.put("bid",27);
        Map m = this.bookService.list5(map);
        System.out.println(m);
    }

    /**
     * 分页
     */
    @Test
    public void listPage(){
        Map map=new HashMap();
        map.put("bname", StringUtils.toLikeStr("圣墟"));
        PageBean pageBean=new PageBean();
        List<Map> list = this.bookService.listPager(map, pageBean);
        for (Map m : list) {
            System.out.println(m);
        }
    }

    /**
     * 特殊字符处理
     */
    @Test
    public void sqlSpecial(){
        BookVo bookVo=new BookVo();
        bookVo.setMax(30);
        bookVo.setMin(20);
//        List
        List<Map> list = this.bookService.list7(bookVo);
        for (Map m : list) {
            System.out.println(m);
        }
    }


}