pagingutils.java

一个JAVA分页解决方案

package com.ctic.core.pub.common;

import java.util.Map;

import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.PropertyUtils;

import com.ctic.core.prod.common.extproperty.DynamicBean;

/**
 * 处理分页信息的工具类
 * 
 * @author Tu_Minglei
 */
public class PagingUtils {
	private static final boolean debug = true;

	/**
	 * 是否能支持分页信息的存取
	 * @param obj
	 * @return
	 */
	public static boolean canSupportPaging(Object obj){
		if((obj instanceof DynamicBean) || (obj instanceof Map)) return true;
		if(PropertyUtils.isReadable(obj, "skipResults") && PropertyUtils.isWriteable(obj, "skipResults")
				&& PropertyUtils.isReadable(obj, "maxResults") && PropertyUtils.isWriteable(obj, "maxResults"))
			return true;
		
		if(debug)
			System.out.println("in PagingUtils.canSupportPaging() -- >> Cannot support paging: "+obj);
		
		return false;
	}
	
	/**
	 * 重置分页相关的参数值
	 * @param obj
	 */
	public static void resetPagingParams(Object obj){
		if(canSupportPaging(obj)){
			setSkipResults(obj, IBATIS_NO_SKIPPED_RESULTS);
			setMaxResults(obj, IBATIS_NO_MAXIMUM_RESULTS);
		}
	}
	
	/**++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*
	 * 						存取分页参数信息
	 **++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
	/**
	 * 填入需忽略的记录数
	 * @param paramObject
	 * @param skipResults
	 */
	public static void setSkipResults(Object paramObject, int skipResults){
		if(paramObject instanceof DynamicBean){
			((DynamicBean)paramObject).set("skipResults", skipResults);
			return;
		}
		
		if(paramObject instanceof Map){
			((Map)paramObject).put("skipResults", skipResults);
			return;
		}
		
		try {
			BeanUtils.setProperty(paramObject, "skipResults", skipResults);
		} catch (Exception e) {
			if(debug)
				System.out.println("in PagingUtils.setSkipResults() -- >> Cannot set value for property skipResults");
		}
	}
	
	/**
	 * 填入欲获取的最大记录数
	 * @param paramObject
	 * @param maxResults
	 */
	public static void setMaxResults(Object paramObject, int maxResults){
		if(paramObject instanceof DynamicBean){
			((DynamicBean)paramObject).set("maxResults", maxResults);
			return;
		}
		
		if(paramObject instanceof Map){
			((Map)paramObject).put("maxResults", maxResults);
			return;
		}
		
		try {
			BeanUtils.setProperty(paramObject, "maxResults", maxResults);
		} catch (Exception e) {
			if(debug)
				System.out.println("in PagingUtils.setMaxResults() -- >> Cannot set value for property maxResults");
		}
	}
	
	/**
	 * 获得需忽略的记录数
	 * @param paramObject
	 * @return
	 */
	public static int getSkipResults(Object paramObject){
		if(paramObject instanceof DynamicBean){
			Object temp = ((DynamicBean)paramObject).get("skipResults");
			return (temp == null) ? IBATIS_NO_SKIPPED_RESULTS : (Integer)temp;
		}
		
		if(paramObject instanceof Map){
			Object temp = ((Map)paramObject).get("skipResults");
			return (temp == null) ? IBATIS_NO_SKIPPED_RESULTS : (Integer)temp;
		}
		
		try {
			return Integer.valueOf(BeanUtils.getProperty(paramObject, "skipResults"));
		} catch (Exception e) {
			if(debug)
				System.out.println("in PagingUtils.getSkipResults() -- >> Cannot find value for property skipResults");
		}
		return IBATIS_NO_SKIPPED_RESULTS;
	}
	
	/**
	 * 获得欲获取的最大记录数
	 * @param paramObject
	 * @return
	 */
	public static int getMaxResults(Object paramObject){
		if(paramObject instanceof DynamicBean){
			Object temp = ((DynamicBean)paramObject).get("maxResults");
			return (temp == null) ? IBATIS_NO_MAXIMUM_RESULTS : (Integer)temp;
		}
		
		if(paramObject instanceof Map){
			Object temp = ((Map)paramObject).get("maxResults");
			return (temp == null) ? IBATIS_NO_MAXIMUM_RESULTS : (Integer)temp;
		}
		
		try {
			return Integer.valueOf(BeanUtils.getProperty(paramObject, "maxResults"));
		} catch (Exception e) {
			if(debug)
				System.out.println("in PagingUtils.getMaxResults() -- >> Cannot find value for property maxResults");
		}
		return IBATIS_NO_MAXIMUM_RESULTS;
	}
	
	private static final int IBATIS_NO_SKIPPED_RESULTS = 0;			//== SqlExecutor.NO_SKIPPED_RESULTS
	private static final int IBATIS_NO_MAXIMUM_RESULTS = -999999;	//== SqlExecutor.NO_MAXIMUM_RESULTS
	
}