说起数据库操作，分页绝对是少不了的，一般网站几乎都会有分页功能，下面我们就来了解一下基于mybatis和MySql的分页功能的几种实现方式吧。
一、Sql分页
具体实现：
1.接口下定义分页的方法
List < Student > queryStudentsBySql(Map < String, Object > data);
2.通过对应的xml文件获取所需节点的所有信息
<select id="queryStudentsBySql" parameterType="map" resultMap="studentmapper">
select * from student limit #{currIndex} , #{pageSize}
</select>3.编写service层
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);
}二、数组分页
具体实现：
1.接口定义所需方法
List < Student > queryStudentsByArray();
2.xml中获取需要节点
<select id="queryStudentsByArray" resultMap="studentmapper"> select * from student </select>
3.service层的定义
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
}4.编写控制层实现实现方法
@ResponseBody
@RequestMapping("/student/array/{currPage}/{pageSize}")
public List < Student > getStudentByArray(@PathVariable("currPage") int currPage, @PathVariable("pageSize") int pageSize)
{
List < Student > student = StuServiceIml.queryStudentsByArray(currPage, pageSize);
return student;
}三、拦截器分页
具体实现：
1.创建拦截器，拦截mybatis接口方法中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");
}
}2.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>
3.配置mybatis
<!--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>4.service定义
public List < AccountExt > getAllBookByPage(String pageNo, String pageSize)
{
return accountMapper.getAllBookByPage(Integer.parseInt(pageNo), Integer.parseInt(pageSize));
}5.编写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;
}以上就是mybatis分页的所有内容了，更多java常见问答相关知识请持续关注奇Q工具网了解吧。
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