mybatis四种分页方式

public List<User> queryByArray(int currPage, int pageSize) {
        //查询数据
        List<User> list= mapper.query();
        //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;
        //直接在list中截取
        return list.subList(firstIndex, lastIndex); 
    }    

<select id="queryBySql" parameterType="map" resultMap="usermapper">
        select * from user limit #{currIndex} , #{pageSize}
</select>

public List<User> queryBySql(int currPage, int pageSize) {
        Map<String, Object> data = new HashedMap();
        data.put("currIndex", (currPage-1)*pageSize);
        data.put("pageSize", pageSize);
        return mapper.queryBySql(data);
    }

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");
    }
}

    public List<User> queryByRowBounds( int start, int limit) {
        return mapper.query(new RowBounds(start, limit));
    }