Mybatis分页如何实现?四种常用分页方式你Get到没！

Posted 2021-05-20 Java小叮当

前言

关于Mybatis的知识点总结了一个思维导图分享给大家

数组分页

查询出全部数据，然后再list中截取需要的部分。2021面试题整理。

mybatis接口

List<Student> queryStudentsByArray();

xml配置文件

 <select id="queryStudentsByArray"  resultMap="studentmapper">
        select * from student
 </select>

service

接口
List<Student> queryStudentsByArray(int currPage, int pageSize);
实现接口
 @Override
    public List<Student> queryStudentsByArray(int currPage, int pageSize) {
        //查询全部数据
        List<Student> students = studentMapper.queryStudentsByArray();
        //从第几条数据开始
        int firstIndex = (currPage - 1) * pageSize;
        //到第几条数据结束
        int lastIndex = currPage * pageSize;
        return students.subList(firstIndex, lastIndex); //直接在list中截取
    }

controller

@ResponseBody
@RequestMapping("/student/array/{currPage}/{pageSize}")
public List getStudentByArray(@PathVariable(“currPage”) int currPage, @PathVariable(“pageSize”) int pageSize) {
List student = StuServiceIml.queryStudentsByArray(currPage, pageSize);
return student;
}

sql分页

mybatis接口

List<Student> queryStudentsBySql(Map<String,Object> data);

xml文件

<select id="queryStudentsBySql" parameterType="map" resultMap="studentmapper">
        select * from student limit #{currIndex} , #{pageSize}
</select>

service

接口
List<Student> queryStudentsBySql(int currPage, int pageSize);
实现类
public List<Student> queryStudentsBySql(int currPage, int pageSize) {
        Map<String, Object> data = new HashedMap();
        data.put("currIndex", (currPage-1)*pageSize);
        data.put("pageSize", pageSize);
        return studentMapper.queryStudentsBySql(data);
    }

拦截器分页

创建拦截器，拦截mybatis接口方法id以ByPage结束的语句

package com.autumn.interceptor;

import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.executor.parameter.ParameterHandler;
import org.apache.ibatis.executor.resultset.ResultSetHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.SystemMetaObject;

import java.sql.Connection;
import java.util.Map;
import java.util.Properties;

/**
 * @Intercepts 说明是一个拦截器
 * @Signature 拦截器的签名
 * type 拦截的类型 四大对象之一( Executor,ResultSetHandler,ParameterHandler,StatementHandler)
 * method 拦截的方法
 * args 参数,高版本需要加个Integer.class参数,不然会报错
 */
@Intercepts({@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class})})
public class MyPageInterceptor implements Interceptor {

    //每页显示的条目数
    private int pageSize;
    //当前现实的页数
    private int currPage;
    //数据库类型
    private String dbType;


    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        //获取StatementHandler，默认是RoutingStatementHandler
        StatementHandler statementHandler = (StatementHandler) invocation.getTarget();
        //获取statementHandler包装类
        MetaObject MetaObjectHandler = SystemMetaObject.forObject(statementHandler);

        //分离代理对象链
        while (MetaObjectHandler.hasGetter("h")) {
            Object obj = MetaObjectHandler.getValue("h");
            MetaObjectHandler = SystemMetaObject.forObject(obj);
        }

        while (MetaObjectHandler.hasGetter("target")) {
            Object obj = MetaObjectHandler.getValue("target");
            MetaObjectHandler = SystemMetaObject.forObject(obj);
        }

        //获取连接对象
        //Connection connection = (Connection) invocation.getArgs()[0];


        //object.getValue("delegate");  获取StatementHandler的实现类

        //获取查询接口映射的相关信息
        MappedStatement mappedStatement = (MappedStatement) MetaObjectHandler.getValue("delegate.mappedStatement");
        String mapId = mappedStatement.getId();

        //statementHandler.getBoundSql().getParameterObject();

        //拦截以.ByPage结尾的请求，分页功能的统一实现
        if (mapId.matches(".+ByPage$")) {
            //获取进行数据库操作时管理参数的handler
            ParameterHandler parameterHandler = (ParameterHandler) MetaObjectHandler.getValue("delegate.parameterHandler");
            //获取请求时的参数
            Map<String, Object> paraObject = (Map<String, Object>) parameterHandler.getParameterObject();
            //也可以这样获取
            //paraObject = (Map<String, Object>) statementHandler.getBoundSql().getParameterObject();

            //参数名称和在service中设置到map中的名称一致
            currPage = (int) paraObject.get("currPage");
            pageSize = (int) paraObject.get("pageSize");

            String sql = (String) MetaObjectHandler.getValue("delegate.boundSql.sql");
            //也可以通过statementHandler直接获取
            //sql = statementHandler.getBoundSql().getSql();

            //构建分页功能的sql语句
            String limitSql;
            sql = sql.trim();
            limitSql = sql + " limit " + (currPage - 1) * pageSize + "," + pageSize;

            //将构建完成的分页sql语句赋值个体'delegate.boundSql.sql'，偷天换日
            MetaObjectHandler.setValue("delegate.boundSql.sql", limitSql);
        }
        //调用原对象的方法，进入责任链的下一级
        return invocation.proceed();
    }


    //获取代理对象
    @Override
    public Object plugin(Object o) {
        //生成object对象的动态代理对象
        return Plugin.wrap(o, this);
    }

    //设置代理对象的参数
    @Override
    public void setProperties(Properties properties) {
        //如果项目中分页的pageSize是统一的，也可以在这里统一配置和获取，这样就不用每次请求都传递pageSize参数了。参数是在配置拦截器时配置的。
        String limit1 = properties.getProperty("limit", "10");
        this.pageSize = Integer.valueOf(limit1);
        this.dbType = properties.getProperty("dbType", "mysql");
    }
}

配置文件SqlMapConfig.xml

<configuration>

    <plugins>
        <plugin interceptor="com.autumn.interceptor.MyPageInterceptor">
            <property name="limit" value="10"/>
            <property name="dbType" value="mysql"/>
        </plugin>
    </plugins>

</configuration>

mybatis配置

<!--接口-->
List<AccountExt> getAllBookByPage(@Param("currPage")Integer pageNo,@Param("pageSize")Integer pageSize);
<!--xml配置文件-->
  <sql id="getAllBooksql" >
    acc.id, acc.cateCode, cate_name, user_id,u.name as user_name, money, remark, time
  </sql>
  <select id="getAllBook" resultType="com.autumn.pojo.AccountExt" >
    select
    <include refid="getAllBooksql" />
    from account as acc
  </select>

service

java
    public List<AccountExt> getAllBookByPage(String pageNo,String pageSize) {
        return accountMapper.getAllBookByPage(Integer.parseInt(pageNo),Integer.parseInt(pageSize));
    }

controller

@RequestMapping("/getAllBook")
@ResponseBody
public Page getAllBook(String pageNo,String pageSize,HttpServletRequest request,HttpServletResponse response){
    pageNo=pageNo==null?"1":pageNo;   //当前页码
    pageSize=pageSize==null?"5":pageSize;   //页面大小
    //获取当前页数据
    List<AccountExt> list = bookService.getAllBookByPage(pageNo,pageSize);
    //获取总数据大小
    int totals = bookService.getAllBook();
    //封装返回结果
    Page page = new Page();
    page.setTotal(totals+"");
    page.setRows(list);
    return page;
}

Page实体类

package com.autumn.pojo;

import java.util.List;

/**
 * Created by Autumn on 2018/6/21.
 */
public class Page {
    private String pageNo = null;
    private String pageSize = null;
    private String total = null;
    private List rows = null;

    public String getTotal() {
        return total;
    }

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

    public List getRows() {
        return rows;
    }

    public void setRows(List rows) {
        this.rows = rows;
    }

    public String getPageNo() {
        return pageNo;
    }

    public void setPageNo(String pageNo) {
        this.pageNo = pageNo;
    }

    public String getPageSize() {
        return pageSize;
    }

    public void setPageSize(String pageSize) {
        this.pageSize = pageSize;
    }

}

前端

bootstrap-table接受数据格式

复制代码
{
  "total": 3,
  "rows": [
    {
      "id": 0,
      "name": "Item 0",
      "price": "$0"
    },
    {
      "id": 1,
      "name": "Item 1",
      "price": "$1"
    }
  ]
}

boostrap-table用法

var $table = $('#table');
    $table.bootstrapTable({
    url: "/${appName}/manager/bookController/getAllBook",
    method: 'post',
    contentType: "application/x-www-form-urlencoded",
    dataType: "json",
    pagination: true, //分页
    sidePagination: "server", //服务端处理分页
    pageList: [5, 10, 25],
    pageSize: 5,
    pageNumber:1,
    //toolbar:"#tb",
    singleSelect: false,
    queryParamsType : "limit",
    queryParams: function queryParams(params) {   //设置查询参数
      var param = {
        pageNo: params.offset/params.limit+1,  //offset为数据开始索引,转换为显示当前页
        pageSize: params.limit  //页面大小
      };
      console.info(params);   //查看参数是什么
      console.info(param);   //查看自定义的参数
      return param;
    },
    cache: false,
    //data-locale: "zh-CN", //表格汉化
    //search: true, //显示搜索框
    columns: [
            {
                checkbox: true
            },
            {
                title: '消费类型',
                field: 'cate_name',
                valign: 'middle'
            },
            {
                title: '消费金额',
                field: 'money',
                valign: 'middle',
                formatter:function(value,row,index){
                    if(!isNaN(value)){   //是数字
                        return value/100;
                    }
                }
            },
            {
                title: '备注',
                field: 'remark',
                valign: 'middle'
            },
            {
                title: '消费时间',
                field: 'time',
                valign: 'middle'
            },
            {
                title: '操作',
                field: '',
                formatter:function(value,row,index){
                    var f = '<a href="#" class="btn btn-gmtx-define1" οnclick="delBook(\\''+ row.id +'\\')">删除</a> ';
                    return f;
                   }
            }
        ]
      });
  });

RowBounds分页

数据量小时，RowBounds不失为一种好办法。但是数据量大时，实现拦截器就很有必要了。

mybatis接口加入RowBounds参数

public List queryUsersByPage(String userName, RowBounds rowBounds);

service

  @Override
    @Transactional(isolation = Isolation.READ_COMMITTED, propagation = Propagation.SUPPORTS)
    public List<RoleBean> queryRolesByPage(String roleName, int start, int limit) {
        return roleDao.queryRolesByPage(roleName, new RowBounds(start, limit));
    }

最后

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