步骤1:先运行，看到成果，再学习
步骤2:模拟和排错
步骤3:减少100条catgory数据
步骤4:批改Category.xml
步骤5:测试
步骤6:注解形式
步骤 1 : 先运行，看到成果，再学习
老规矩，先下载下载区(点击进入)的可运行我的项目，配置运行起来，确认可用之后，再学习做了哪些步骤以达到这样的成果。
步骤 2 : 模拟和排错
在确保可运行我的项目可能正确无误地运行之后，再严格照着教程的步骤，对代码模拟一遍。
模拟过程不免代码有出入，导致无奈失去冀望的运行后果，此时此刻通过比拟正确答案 ( 可运行我的项目 ) 和本人的代码，来定位问题所在。
采纳这种形式，学习有成果，排错有效率，能够较为显著地晋升学习速度，跨过学习路上的各个槛。
举荐应用diffmerge软件，进行文件夹比拟。把你本人做的我的项目文件夹，和我的可运行我的项目文件夹进行比拟。
这个软件很牛逼的，能够晓得文件夹里哪两个文件不对，并且很显著地标记进去
这里提供了绿色装置和应用教程：diffmerge 下载和应用教程
步骤 3 : 减少100条catgory数据
为了察看分页查问的成果，把分类表里的数据都删除掉，而后新增100个数据
package com.how2java;import java.io.IOException;import java.io.InputStream;import java.util.List;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import com.how2java.pojo.Category;public class TestMybatis { public static void main(String[] args) throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sqlSessionFactory.openSession(); List<Category> cs = session.selectList("listCategory"); for (Category c : cs) { session.delete("deleteCategory", c); } for (int i = 0; i < 100; i++) { Category c = new Category(); c.setName("category name " + i); session.insert("addCategory", c); } List<Category> cs2 = session.selectList("listCategory"); for (Category c : cs2) { System.out.println(c.getName()); } session.commit(); session.close(); }}步骤 4 : 批改Category.xml
新增limit
<?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.how2java.pojo"> <insert id="addCategory" parameterType="Category" > insert into category_ ( name ) values (#{name}) </insert> <delete id="deleteCategory" parameterType="Category" > delete from category_ where id= #{id} </delete> <select id="getCategory" parameterType="_int" resultType="Category"> select * from category_ where id= #{id} </select> <update id="updateCategory" parameterType="Category" > update category_ set name=#{name} where id=#{id} </update> <select id="listCategory" resultType="Category"> select * from category_ <if test="start!=null and count!=null"> limit #{start},#{count} </if> </select></mapper>步骤 5 : 测试
用注解形式再做一遍
注： start是指从第0个开始，如果是第二页，那么就是第5个开始。
注： count参数是指每页有5条数据
- CategoryMapper.java
- TestMybatis.java
package com.how2java.mapper;import java.util.List;import org.apache.ibatis.annotations.Many;import org.apache.ibatis.annotations.Param;import org.apache.ibatis.annotations.Result;import org.apache.ibatis.annotations.Results;import org.apache.ibatis.annotations.Select;import com.how2java.pojo.Category;public interface CategoryMapper { public List<Category> list(); public List<Category> listByPage(@Param("start") int start, @Param("count")int count);}package com.how2java;import java.io.IOException;import java.io.InputStream;import java.util.HashMap;import java.util.List;import java.util.Map;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import com.how2java.mapper.CategoryMapper;import com.how2java.pojo.Category;public class TestMybatis { public static void main(String[] args) throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sqlSessionFactory.openSession();// xmlWay(session); annotationWay(session); session.commit(); session.close(); } private static void xmlWay(SqlSession session) { Map<String,Object> params = new HashMap<>(); params.put("start", 0); params.put("count", 5); List<Category> cs =session.selectList("listCategory", params); for (Category c : cs) { System.out.println(c); } } private static void annotationWay(SqlSession session) { CategoryMapper mapper = session.getMapper(CategoryMapper.class); List<Category> cs =mapper.listByPage(0, 5); for (Category c : cs) { System.out.println(c); } }}步骤 6 : 注解形式
- CategoryMapper.java
- TestMybatis.java
package com.how2java.mapper;import java.util.List;import org.apache.ibatis.annotations.Many;import org.apache.ibatis.annotations.Param;import org.apache.ibatis.annotations.Result;import org.apache.ibatis.annotations.Results;import org.apache.ibatis.annotations.Select;import com.how2java.pojo.Category;public interface CategoryMapper { @Select(" select * from category_ ") @Results({@Result(property = "products", javaType = List.class, column = "id", many = @Many(select = "com.how2java.mapper.ProductMapper.listByCategory"))}) public List<Category> list(); @Select(" select * from category_ limit #{start},#{count}") public List<Category> listByPage(@Param("start") int start, @Param("count")int count);}package com.how2java;import java.io.IOException;import java.io.InputStream;import java.util.List;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import com.how2java.mapper.CategoryMapper;import com.how2java.pojo.Category;public class TestMybatis { public static void main(String[] args) throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sqlSessionFactory.openSession(); CategoryMapper mapper = session.getMapper(CategoryMapper.class); List<Category> cs =mapper.listByPage(0, 5); for (Category c : cs) { System.out.println(c); } session.commit(); session.close(); }}更多内容，点击理解： https://how2j.cn/k/mybatis/mybatis-annotation-pagination/1100.html