MyBatis的动态sql和分页

前言动态sqlforeach标签的使用模糊查询查询返回结果集 动态分页整体代码 遇到的错误 总结

前言

这篇博客主要为大家分享的是动态sql和分页的相关知识，基于我的上一篇博客MyBatis搭建好的基础上！

动态sql

使用的动态sql作用if判断trim去除字符串左右两端空格foreach遍历集合，批量查询、通常用于in关键字其他choose、set、where

这里博主着重讲一下foreach标签的使用！

foreach标签的使用

foreach的原始sql

select * from 表名 where id in 集合名

而foreach的动态sql对比原始的sql不同的是

in关键字后面接的集合名变成了一个动态的数组！

BookMapper中写一个遍历所有数据的方法

这里一定要记得加上参数的这个注解！

同步，BookService也需要加上同样的方法

BookServiceImpl中实现已创建好的接口

在对应的BookMapper.xml中配置

测试成功后的结果

模糊查询

StringUtils

用来模糊查询的工具类

package com.wangqiuping.util; /** * @author sunnyWang * @site 公司的网址 * @company xxx公司 * @create 2020-10-21 13:02 */ public class StringUtils { public static String toLikeStr(String str){ return "%"+str+"%"; } }

首先在BookMapper接口中加入模糊查询的三种方法

这里一定要记得加上注解

同步在BookService中也加入同样的方法

其次，在BookServiceImpl中加入实现的接口方法

第一种：参数中直接加入%%

在BookMapper.xml中配置需要注入的sql

第二种:使用${…}

注意这里不建议使用该方式，有SQL注入风险

第三种:SQL字符串拼接concat

最终模糊查询的结果

查询返回结果集

BookVo

用来展示页面数据和传参

package com.wangqiuping.model; import java.util.List; /** * @author sunnyWang * @site 公司的网址 * @company xxx公司 * @create 2020-10-21 14:25 * 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 Float min; private Float max; private List<Integer> bookIds; 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<Integer> getBookIds() { return bookIds; } public void setBookIds(List<Integer> bookIds) { this.bookIds = bookIds; } }

适合使用返回值是自定义实体类的情况 resultMap

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

动态分页

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

以下就是使用MyBatis的插件步骤

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中配置拦截器

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

<plugins> <plugin interceptor="com.github.pagehelper.PageInterceptor"> </plugin> </plugins>

插件该段代码块的位置

3、在BookMapper中配置分页插件

<select id="listPager" resultType="java.util.Map" parameterType="java.util.Map"> select * from t_mvc_book where bname like #{bname} </select>

4、BookMapper接口中加入分页的方法

List<Map> listPager(Map map);

5、BookService中加入分页的方法

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

6、BookServiceImpl实现分页的方法

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("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 list; }

4、测试类中处理分页结果

@Test public void listPager(){ Map map=new HashMap(); map.put("bname","%圣墟%"); PageBean pageBean=new PageBean(); List<Map> list = this.bookService.listPager(map, pageBean); for (Map map1 :list){ System.out.println(map1); } }

分页结果

分页相关信息

输出的分页条数

整体代码

pom

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.wangqiuping</groupId> <artifactId>MyBatis</artifactId> <version>1.0-SNAPSHOT</version> <properties> <maven.compiler.source>1.8</maven.compiler.source> <maven.compiler.target>1.8</maven.compiler.target> </properties> <dependencies> <!-- ********************** junit单元测试依赖 ********************** --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> <!-- ********************** Java Servlet API ********************** --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.0</version> <scope>provided</scope> </dependency> <!-- ********************** Mybatis依赖 ********************** --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.5</version> </dependency> <!-- ********************** Mysql JDBC驱动 ********************** --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.44</version> </dependency> <!-- ********************** 日志配置 ********************** --> <!--记得修改mybatis.cfg.xml添加如下内容--> <!--<setting name="logImpl" value="LOG4J2"/>--> <!--核心log4j2jar包--> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-core</artifactId> <version>2.9.1</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-api</artifactId> <version>2.9.1</version> </dependency> <!--web工程需要包含log4j-web，非web工程不需要--> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-web</artifactId> <version>2.9.1</version> </dependency> <!--这里配置分页需要使用的插件--> <dependency> <groupId>com.github.pagehelper</groupId> <artifactId>pagehelper</artifactId> <version>5.1.2</version> </dependency> </dependencies> <build> <resources> <!--解决mybatis-generator-maven-plugin运行时没有将XxxMapper.xml文件放入target文件夹的问题--> <resource> <directory>src/main/java</directory> <includes> <include>**/*.xml</include> </includes> </resource> <!--解决mybatis-generator-maven-plugin运行时没有将jdbc.properites文件放入target文件夹的问题--> <resource> <directory>src/main/resources</directory> <includes> <include>jdbc.properties</include> <include>*.xml</include> </includes> </resource> </resources> <plugins> <plugin> <groupId>org.mybatis.generator</groupId> <artifactId>mybatis-generator-maven-plugin</artifactId> <version>1.3.2</version> <dependencies> <!--使用Mybatis-generator插件不能使用太高版本的mysql驱动 --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.44</version> </dependency> </dependencies> <configuration> <overwrite>true</overwrite> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.8.0</version> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <version>2.22.1</version> <configuration> <skipTests>true</skipTests> </configuration> </plugin> </plugins> </build> </project>

BookMapper

package com.wangqiuping.mapper; import com.wangqiuping.model.Book; import com.wangqiuping.model.BookVo; import org.apache.ibatis.annotations.Param; import java.util.List; import java.util.Map; /** * 这个类就相当于Dao层 */ 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 * @param bookIds * @return */ List<Book> selectBooksList(@Param("bookIds") List bookIds); //模糊查询第一种方式 List<Book> selectBooksLike1(@Param("bname")String bname); //模糊查询第二种方式 List<Book> selectBooksLike2(@Param("bname")String bname); //模糊查询第三种方式 List<Book> selectBooksLike3(@Param("bname")String bname); /** * mybatis结果集处理的五种情况 * @return */ List<Book> list1(); List<Book> list2(); List<Book> list3(BookVo bookVo); List<Map> list4(Map map); Map list5(Map map); //动态分页 List<Map> listPager(Map map); }

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.wangqiuping.mapper.BookMapper" > <resultMap id="BaseResultMap" type="com.wangqiuping.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.wangqiuping.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.wangqiuping.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.wangqiuping.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.wangqiuping.model.Book" > update t_mvc_book set bname = #{bname,jdbcType=VARCHAR}, price = #{price,jdbcType=REAL} where bid = #{bid,jdbcType=INTEGER} </update> <!--foreach标签的使用--> <select id="selectBooksList" resultType="com.wangqiuping.model.Book" parameterType="java.util.List"> select *from t_mvc_book where bid in <foreach collection="bookIds" item="bid" open="(" close=")" separator=","> #{bid} </foreach> </select> <!--模糊查询第一种方式的使用--> <select id="selectBooksLike1" resultType="com.wangqiuping.model.Book" parameterType="java.lang.String" > select * from t_mvc_book where bname like #{bname} </select> <!--模糊查询第二种方式的使用--> <select id="selectBooksLike2" resultType="com.wangqiuping.model.Book" parameterType="java.lang.String" > select * from t_mvc_book where bname like '${bname}' </select> <!--模糊查询第三种方式的使用--> <select id="selectBooksLike3" resultType="com.wangqiuping.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.wangqiuping.model.Book"> select * from t_mvc_book </select> <select id="list3" resultType="com.wangqiuping.model.Book" parameterType="com.wangqiuping.model.BookVo"> select * from t_mvc_book where bid in <foreach collection="bookIds" item="bid" open="(" close=")" separator=","> #{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" item="bid" open="(" close=")" separator=","> #{bid} </foreach> </select> <!--<select id="list5" resultType="com.wangqiuping.model.Book" parameterType="java.util.Map"> select * from t_mvc_book where bid =#{bid} </select>--> <select id="list5" resultType="java.util.Map" parameterType="java.util.Map"> select * from t_mvc_book where bid = #{bid} </select> <!--动态分页--> <select id="listPager" resultType="java.util.Map" parameterType="java.util.Map"> select * from t_mvc_book where bname like #{bname} </select> </mapper>

mybatis.cfg.xml

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration> <!-- 引入外部配置文件 --> <properties resource="jdbc.properties"/> <settings> <setting name="logImpl" value="LOG4J2"/> </settings> <!-- 别名 --> <typeAliases> </typeAliases> <!--这里加入分页需要使用的插件--> <plugins> <plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin> </plugins> <!-- 配置mybatis运行环境 --> <environments default="development"> <environment id="development"> <!-- type="JDBC" 代表使用JDBC的提交和回滚来管理事务 --> <transactionManager type="jdbc"/> <!-- mybatis提供了3种数据源类型，分别是：POOLED,UNPOOLED,JNDI --> <!-- POOLED 表示支持JDBC数据源连接池 --> <!-- UNPOOLED 表示不支持数据源连接池 --> <!-- JNDI 表示支持外部数据源连接池 --> <dataSource type="POOLED"> <property name="driver" value="${jdbc.driver}"/> <property name="url" value="${jdbc.url}"/> <property name="username" value="${jdbc.username}"/> <property name="password" value="${jdbc.password}"/> </dataSource> </environment> </environments> <mappers> <!----> <mapper resource="com/wangqiuping/mapper/BookMapper.xml"></mapper> </mappers> </configuration>

BookService

package com.wangqiuping.service; import com.wangqiuping.model.Book; import com.wangqiuping.model.BookVo; import com.wangqiuping.util.PageBean; import org.apache.ibatis.annotations.Param; import java.util.List; import java.util.Map; /** * @author sunnyWang * @site 公司的网址 * @company xxx公司 * @create 2020-10-15 20:19 * 这个接口就相当于Biz层 * 只需要将生成的Mapper类中的方法复制过来u即可 */ 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); //foreach遍历 List<Book> selectBooksList(List bookIds); /** * MyBatis对模糊查询共有三种方式 * #{} * ${} * concat * @param bname * @return */ //模糊查询第一种方式 List<Book> selectBooksLike1(String bname); //模糊查询第二种方式 List<Book> selectBooksLike2(String bname); //模糊查询第三种方式 List<Book> selectBooksLike3(String bname); //查询返回结果集的五种方式 List<Book> list1(); List<Book> list2(); List<Book> list3(BookVo bookVo); List<Map> list3(Map map); List<Map> list4(Map map); Map list5(Map map); //动态分页 List<Map> listPager(Map map, PageBean pageBean); }

BookServiceImpl

package com.wangqiuping.service.Impl; import com.github.pagehelper.PageHelper; import com.github.pagehelper.PageInfo; import com.wangqiuping.mapper.BookMapper; import com.wangqiuping.model.Book; import com.wangqiuping.model.BookVo; import com.wangqiuping.service.BookService; import com.wangqiuping.util.PageBean; import java.util.List; import java.util.Map; /** * @author sunnyWang * @site 公司的网址 * @company xxx公司 * @create 2020-10-15 20:24 */ 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> selectBooksList(List bookIds) { return bookMapper.selectBooksList(bookIds); } @Override public List<Book> selectBooksLike1(String bname) { return bookMapper.selectBooksLike1(bname); } @Override public List<Book> selectBooksLike2(String bname) { return bookMapper.selectBooksLike2(bname); } @Override public List<Book> selectBooksLike3(String bname) { return bookMapper.selectBooksLike3(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> list3(Map map) { return bookMapper.list4(map); } @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> list = bookMapper.listPager(map); if(pageBean!=null&&pageBean.isPagination()){ PageInfo pageInfo=new PageInfo(list); 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 list; } }

BookServiceImplTest

package com.wangqiuping.service; import com.wangqiuping.mapper.BookMapper; import com.wangqiuping.model.Book; import com.wangqiuping.model.BookVo; import com.wangqiuping.service.Impl.BookServiceImpl; import com.wangqiuping.util.PageBean; import com.wangqiuping.util.SessionUtil; import com.wangqiuping.util.StringUtils; import org.apache.ibatis.session.SqlSession; import org.junit.After; import org.junit.Before; import org.junit.Test; import java.rmi.server.ObjID; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import static org.junit.Assert.*; /** * @author sunnyWang * @site 公司的网址 * @company xxx公司 * @create 2020-10-16 10:29 */ public class BookServiceTest { private BookService bookService; private SqlSession sqlSession; @Before public void setUp() throws Exception { BookServiceImpl bookService=new BookServiceImpl(); sqlSession= SessionUtil.openSession(); BookMapper mapper=sqlSession.getMapper(BookMapper.class); bookService.setBookMapper(mapper); this.bookService=bookService; } //增加 @Test public void insert() { Book book=new Book(); book.setBid(4108); book.setBname("使用MyBatis进行插入数据2"); book.setPrice(10f); this.bookService.insert(book); } //删除 @Test public void deleteByPrimary(){ this.bookService.deleteByPrimaryKey(26); } //查询 @Test public void selectByPrimaryKey() { Book book=this.bookService.selectByPrimaryKey(11); System.out.println(book); } //修改 @Test public void updateByPrimaryKey(){ Book b=this.bookService.selectByPrimaryKey(68); b.setBname("大话西游1"); b.setPrice(100f); this.bookService.updateByPrimaryKey(b); } //遍历数据 @Test public void selectBooksList(){ List list= new ArrayList(); list.add(12); list.add(16); list.add(18); List<Book> books = this.bookService.selectBooksList(list); for (Book b : books) { System.out.println(b); } } @Test public void selectBooksLike(){ String bname="大话西游"; //第一种方式 //List<Book> books = this.bookService.selectBooksLike1(StringUtils.toLikeStr(bname)); //第二种方式 List<Book> books = this.bookService.selectBooksLike2(StringUtils.toLikeStr(bname)); //第三种方式 //List<Book> books = this.bookService.selectBooksLike3(bname); for (Book b:books) { System.out.println(b); } } @Test public void list(){ //第一种方式 //List<Book> books = this.bookService.list1(); //第二种方式 //List<Book> books = this.bookService.list2(); //第三种方式 List list=new ArrayList(); list.add(12); list.add(22); list.add(33); /*BookVo bookVo=new BookVo(); bookVo.setBookIds(list); List<Book> books= this.bookService.list3(bookVo); for(Book b:books){ System.out.println(b); }*/ //第四种方式 Map map=new HashMap(); /* map.put("bookIds",list); List<Map> mapList=this.bookService.list4(map); for (Map m:mapList){ System.out.println(m); }*/ //第五种方式 map.put("bid",11); System.out.println(this.bookService.list5(map)); } //分页 @Test public void listPager(){ Map map=new HashMap(); map.put("bname","%圣墟%"); PageBean pageBean=new PageBean(); List<Map> list = this.bookService.listPager(map, pageBean); for (Map map1 :list){ System.out.println(map1); } } @After public void tearDown() throws Exception { sqlSession.commit(); sqlSession.close(); } }

PageBean

package com.wangqiuping.util; import javax.servlet.http.HttpServletRequest; import java.io.Serializable; import java.util.Map; /** * @author sunnyWang * @site 公司的网址 * @company xxx公司 * @create 2020-10-26 16:14 */ 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 + "]"; } }

遇到的错误

错误一

Maven:Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.12.4

报错截图

报错原因：maven中没有自动创建可以通过编译的插件！

解决方案：在pom的plugins下添加以下依赖就好

<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.8.0</version> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> <!--加入这个插件估计就不会报以上错误了--> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <version>2.22.1</version> <configuration> <skipTests>true</skipTests> </configuration> </plugin>

错误二

MyBatis中的congiuration标签报红

报错截图

解决方案

按照configuration的配置顺序进行调整

正确的配置顺序如下

1.properties 2.settings 3.typeAliases 4.typeHandlers 5.objectFactory 5.objectWrapperFactory 6.reflectorFactory 7.plugins 8.environments 9.databaseIdProvider 10.mappers

博主个人出现这个错误，是因为将plugins代码块的位置写错了~

总结

MyBatis的动态sql主要是根据原生sql演变而来的，而动态分页的实现过程只需要缕清思路就好，内容就分享到这里啦~