viewpagehelper.java

java分页bean

package com.page;

import java.util.HashMap;
import java.util.Map;

/* 分页辅助类,用于减化Controller中的代码
 */
public class ViewPageHelper {
	private static final int FIRST_PAGE_VALUE = 1;

	private static final int PREVIOUS_PAGE_VALUE = 2;

	private static final int NEXT_PAGE_VALUE = 3;

	private static final int LAST_PAGE_VALUE = 4;

	private static final int SPECIAL_PAGE_VALUE = 5;

	public static final String FIRST_PAGE = "FIRST_PAGE";

	public static final String PREVIOUS_PAGE = "PREVIOUS_PAGE";

	public static final String NEXT_PAGE = "NEXT_PAGE";

	public static final String LAST_PAGE = "LAST_PAGE";

	public static final String SPECIAL_PAGE = "SPECIAL_PAGE";

	/** 分页动作参数名* */
	public static final String PAGE_ACTION = "page_action";

	/** 分页对象属性名* */
	public static final String SESSION_PAGE = "session_page";

	/** 页号参数名* */
	public static final String PAGE_NO = "page_no";

	private static Map actionMap = new HashMap();
	static {
		actionMap.put(FIRST_PAGE, new Integer(FIRST_PAGE_VALUE));
		actionMap.put(PREVIOUS_PAGE, new Integer(PREVIOUS_PAGE_VALUE));
		actionMap.put(NEXT_PAGE, new Integer(NEXT_PAGE_VALUE));
		actionMap.put(LAST_PAGE, new Integer(LAST_PAGE_VALUE));
		actionMap.put(SPECIAL_PAGE, new Integer(SPECIAL_PAGE_VALUE));
	}

	/**
	 * 执行分页动作
	 * 
	 * @param page
	 *            分页对象
	 * @param action
	 *            分页动作参数
	 * @param pageIndex
	 *            页号
	 */
	public static void doAction(ViewPage page, String action, int pageIndex) {
		int actionIndex = 0;
		if (page == null) {
			throw new NullPointerException("Page对象null");
		}
		if (action == null || "".equals(action)) {
			throw new IllegalArgumentException("无效的分页动作参数null");
		}
		action = action.toUpperCase();
		if (!actionMap.containsKey(action)) {
			throw new UnsupportedOperationException("不支持的分页动作参数:" + action);
		}
		Integer index = (Integer) actionMap.get(action);
		actionIndex = index.intValue();
		switch (actionIndex) {
		case FIRST_PAGE_VALUE:
			page.gotoFirstPage();
			break;
		case PREVIOUS_PAGE_VALUE:
			page.gotoPreviousPage();
			break;
		case NEXT_PAGE_VALUE:
			page.gotoNextPage();
			break;
		case LAST_PAGE_VALUE:
			page.gotoLastPage();
			break;
		case SPECIAL_PAGE_VALUE:
			page.gotoPage(pageIndex);
		}
	}

	public static void doAction(ViewPage page, String action) {
		doAction(page, action, 1);
	}
}