几种常见mybatis分页实现方式

package com.xxx.mybatis.bean;
import java.util.List;
public class Pager<T> {
	private int page;//分页起始页
	private int size;//每页记录数
	private List<T> rows;//返回的记录集合
	private long total;//总记录条数
	public int getPage() {
		return page;
	}
	public void setPage(int page) {
		this.page = page;
	}
	public int getSize() {
		return size;
	}
	public void setSize(int size) {
		this.size = size;
	}
	public List<T> getRows() {
		return rows;
	}
	public void setRows(List<T> rows) {
		this.rows = rows;
	}
	public long getTotal() {
		return total;
	}
	public void setTotal(long total) {
		this.total = total;
	}
}

public List<User> findByPager(Map<String, Object> params);
public long count();

<select id="findByPager" resultType="com.xxx.mybatis.domain.User">
	select * from xx_user limit #{page},#{size}
</select>
<select id="count" resultType="long">
	select count(1) from xx_user
</select>

public Pager<User> findByPager(int page,int size){
	Map<String, Object> params = new HashMap<String, Object>();
	params.put("page", (page-1)*size);
	params.put("size", size);
	Pager<User> pager = new Pager<User>();
	List<User> list = userDao.findByPager(params);
	pager.setRows(list);
	pager.setTotal(userDao.count());
	return pager;
}

package com.xxx.mybatis.bean;
import java.sql.Connection;
import java.util.Map;
import java.util.Properties;
import org.apache.ibatis.executor.parameter.ParameterHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.SystemMetaObject;
@Intercepts({@Signature(type=StatementHandler.class,method="prepare",args={Connection.class,Integer.class})})
public class MyPageInterceptor implements Interceptor {
	
	private int page;
	private int size;
	@SuppressWarnings("unused")
	private String dbType;
 
	@SuppressWarnings("unchecked")
	@Override
	public Object intercept(Invocation invocation) throws Throwable {
		System.out.println("plugin is running...");
		StatementHandler statementHandler = (StatementHandler)invocation.getTarget();
		MetaObject metaObject = SystemMetaObject.forObject(statementHandler);
		while(metaObject.hasGetter("h")){
			Object object = metaObject.getValue("h");
			metaObject = SystemMetaObject.forObject(object);
		}
		while(metaObject.hasGetter("target")){
			Object object = metaObject.getValue("target");
			metaObject = SystemMetaObject.forObject(object);
		}
		MappedStatement mappedStatement = (MappedStatement)metaObject.getValue("delegate.mappedStatement");
		String mapId = mappedStatement.getId();
		if(mapId.matches(".+ByPager$")){
			ParameterHandler parameterHandler = (ParameterHandler)metaObject.getValue("delegate.parameterHandler");
			Map<String, Object> params = (Map<String, Object>)parameterHandler.getParameterObject();
			page = (int)params.get("page");
			size = (int)params.get("size");
			String sql = (String) metaObject.getValue("delegate.boundSql.sql");
			sql += " limit "+(page-1)*size +","+size;
			metaObject.setValue("delegate.boundSql.sql", sql);
		}
		return invocation.proceed();
	}
 
	@Override
	public Object plugin(Object target) {
		return Plugin.wrap(target, this);
	}
 
	@Override
	public void setProperties(Properties properties) {
		String limit = properties.getProperty("limit","10");
		this.page = Integer.parseInt(limit);
		this.dbType = properties.getProperty("dbType", "mysql");
	}
 
}

public Pager<User> findByPager(int page,int size){
	Map<String, Object> params = new HashMap<String, Object>();
	params.put("page", page);
	params.put("size", size);
	Pager<User> pager = new Pager<User>();
	List<User> list = userDao.findByPager(params);
	pager.setRows(list);
	pager.setTotal(userDao.count());
	return pager;
}

<dependency>
	<groupId>com.github.pagehelper</groupId>
	<artifactId>pagehelper</artifactId>
	<version>4.2.1</version>
 </dependency>

 <bean id="pageInterceptor" class="com.github.pagehelper.PageHelper">
	<property name="properties">
		<props>
			<prop key="helperDialect">mysql</prop>
			<prop key="reasonable">true</prop>
			<prop key="supportMethodsArguments">true</prop>
			<prop key="params">count=countSql</prop>
		</props>
	</property>
 </bean>
 
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
	<property name="dataSource" ref="dataSource" />
	<property name="mapperLocations"  value="classpath:com/xxx/mybatis/dao/*Mapper.xml"/>
	<property name="plugins" ref="pageInterceptor"></property>
</bean> 

public Pager<User> findByPager(int page,int size){
	Pager<User> pager = new Pager<User>();
	Page<User> res = PageHelper.startPage(page,size);
	userDao.findAll();
	pager.setRows(res.getResult());
	pager.setTotal(res.getTotal());
	return pager;
}