jsp 分页

package com.jmail.code.util;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Enumeration;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

/**
 * @author zero
 * 
 * <pre>
 *  分页类
 *  使用:new Page(request).setRowsCount(120).useGroupPage(10).setNextPage(" >>").setPrePage("<< ").buildPagination();
 *  控制器中可以使用Page 提供的getParameterValue() 等方法获取传来的数据
 *  
 *  获取总记录数:${rowsCount}
 *  获取总页数:${totalPages}
 *  获取当前页数:${p}
 *  获取当前页第一条记录序号:${firstRow}
 *  获取分页代码:${pagesUrl}
 *  获取Page对象:${page}
 *  
 *  定义样式参考:
 *  .currentPage: 定义当前页样式
 *  .otherPage: 定义非当前页样式
 *  .prePage: 上一页
 *  .nextPage: 下一页
 * </pre>
 */
public class Page {
	private static final String PAGE = "p";

	public static final String ENCODING_UTF8 = "utf-8";
	public static final String ENCODING_GBK = "gbk";

	public static final int PAGESIZE_5 = 5;
	public static final int PAGESIZE_10 = 10;
	public static final int PAGESIZE_15 = 15;
	public static final int PAGESIZE_20 = 20;
	public static final int PAGESIZE_30 = 30;
	public static final int PAGESIZE_50 = 50;
	public static final int PAGESIZE_100 = 100;

	// private boolean useEncoding=false;
	private String encoding = ENCODING_UTF8;

	private int totalPages;
	private int currentPage;
	private StringBuilder pagesUrl = new StringBuilder();

	// 配置项
	private int pageSize = PAGESIZE_10;
	private int groupPageSize = 5;
	private boolean useGroupPage = false;

	private HttpServletRequest request;
	private int rowsCount;

	private int currentPageFirstRow;

	// 显示文本
	private String prePage = "上一页";
	private String nextPage = "下一页";
	private String firstPage = "首页";
	private String lastPage = "尾页";

	private boolean displayPreAndNextPageLink = false;

	// 当前页数据
	private List<Object> data;

	public Page(HttpServletRequest request) {
		this.init(request);
		this.request = request;
	}

	/**
	 * @param rowsCount
	 *            总记录数
	 * @param request
	 *            HttpServletRequest
	 */
	public Page(int rowsCount, HttpServletRequest request) {
		this.init(request);
		this.rowsCount = rowsCount;
		this.request = request;
	}

	private void init(HttpServletRequest request) {
		String cp = request.getParameter(PAGE);
		if (cp == null) {
			request.setAttribute(PAGE, 1);
			this.currentPage = 1;
		} else {
			this.currentPage = Integer.parseInt(request.getParameter(PAGE));
		}
	}

	public boolean isDisplayPreAndNextPageLink() {
		return displayPreAndNextPageLink;
	}

	/**
	 * 当当前页面为第一页时,是否显示"上一页".
	 * 
	 * @return
	 */
	public Page displayPreAndNextPageLink() {
		this.displayPreAndNextPageLink = true;
		return this;
	}

	public HttpServletRequest getRequest() {
		return request;
	}

	public String getPagesUrl() {
		return this.pagesUrl.toString();
	}

	public int getTotalPages() {
		return totalPages;
	}

	public int getCurrentPage() {
		return currentPage;
	}

	public int getPageSize() {
		return pageSize;
	}

	public int getRowsCount() {
		return rowsCount;
	}

	public Page setRowsCount(int rowsCount) {
		this.rowsCount = rowsCount;
		return this;
	}

	public int getGroupPageSize() {
		return groupPageSize;
	}

	public boolean isGroupPage() {
		return useGroupPage;
	}

	public Page setPageSize(int pageSize) {
		this.pageSize = pageSize;
		return this;
	}

	/**
	 * 使用组分,默认不使用.
	 * 
	 * @return
	 */
	public Page useGroupPage() {
		this.useGroupPage = true;
		return this;
	}

	public Page useGroupPage(int size) {
		this.useGroupPage = true;
		this.groupPageSize = size;
		return this;
	}

	public int getCurrentPageFirstRow() {
		return currentPageFirstRow = (this.currentPage - 1) * pageSize;
	}

	/**
	 * 设置上一页的显示文本
	 * 
	 * @param prePage
	 */
	public Page setPrePage(String prePage) {
		this.prePage = prePage;
		return this;
	}

	/**
	 * 设置下一页的显示文本
	 * 
	 * @param nextPage
	 */
	public Page setNextPage(String nextPage) {
		this.nextPage = nextPage;
		return this;
	}

	/**
	 * 同页面编码,默认为UTF-8
	 * 
	 * @param encoding
	 * @return
	 */
	public Page useEncoding(String encoding) {
		this.encoding = encoding;
		return this;
	}

	public void setData(List<Object> data) {
		this.data = data;
	}

	public void buildPagination() {
		this.totalPages = (rowsCount + pageSize - 1) / pageSize;
		StringBuilder next = new StringBuilder();
		StringBuilder pre = new StringBuilder();
		StringBuilder otherPageLinks = null;
		StringBuilder url = new StringBuilder(128);
		String baseUrl = request.getRequestURI();

		// 构造查询字符串
		StringBuilder query = new StringBuilder();
		query.append(baseUrl);
		query.append("?");
		Enumeration<?> enume = request.getParameterNames();
		try {
			while (enume.hasMoreElements()) {
				String parName = (String) enume.nextElement();
				if ("uc".equalsIgnoreCase(parName))
					continue;

				if (!PAGE.equalsIgnoreCase(parName)) {
					String v = request.getParameter(parName);
					if (v == null || v.trim().length() == 0)
						continue;
					String value = getParameterValue(parName);
					query.append(parName);
					query.append("=");
					query.append(URLEncoder.encode(value, encoding));
					query.append("&");
					request.setAttribute(parName, value);// ...
				}
			}
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		query.append("uc=y&p=");
		url.append(query);

		if (this.currentPage > this.totalPages || this.currentPage < 1) {
			this.currentPage = 1;
		}

		// 下一页
		if (this.currentPage > 0 && this.currentPage < totalPages) {
			next.append("<a href='").append(url).append(this.currentPage + 1)
					.append("' class='nextPage'>").append(nextPage)
					.append("</a>");
		} else {
			if (this.displayPreAndNextPageLink && totalPages > 1) {
				next.append("<a>").append(this.nextPage).append("</a>");
			}
		}
		// 上一页
		if (this.currentPage > 1 && this.currentPage <= totalPages) {
			pre.append("<a href='").append(url).append(this.currentPage - 1)
					.append("' class='prePage'>").append(prePage)
					.append("</a>");
		} else {
			if (this.displayPreAndNextPageLink && totalPages > 1) {
				pre.append("<a>").append(this.prePage).append("</a>");
			}
		}

		this.pagesUrl.append(pre);// 上一页
		// -----------------------组分页------------------
		if (useGroupPage && this.totalPages > 1) {
			otherPageLinks = new StringBuilder(64);
			if (this.groupPageSize > this.totalPages) {
				this.groupPageSize = this.totalPages;
			}

			int tmp = groupPageSize / 2;
			int leftFirst = 1;
			if (this.currentPage > tmp + 1) {
				leftFirst = this.currentPage - tmp;// 最左边页码
			}
			if (this.currentPage + tmp > this.totalPages) {
				leftFirst = this.totalPages - this.groupPageSize + 1;// 最左边页码
			}
			for (int i = leftFirst; i < this.groupPageSize + leftFirst; i++) {
				if (i == this.currentPage) {
					otherPageLinks.append("<a  class='currentPage'><span>")
							.append(i).append("</span></a>");
				} else if (i <= this.totalPages) {
					otherPageLinks.append("<a href='").append(url).append(i)
							.append("' class='otherPage'><span>").append(i)
							.append("</span></a>");
				}
			}
			this.pagesUrl.append(otherPageLinks);// 组分页
		}
		this.pagesUrl.append(next);// 下一页

		currentPageFirstRow = (this.currentPage - 1) * pageSize;
		
		request.setAttribute(PAGE, this.currentPage);
		request.setAttribute("firstRow", this.currentPageFirstRow);
		request.setAttribute("totalPages", this.totalPages);
		request.setAttribute("pageSize", this.pageSize);
		request.setAttribute("rowsCount", this.rowsCount);
		request.setAttribute("pagesUrl", this.pagesUrl);
		System.out.println(pagesUrl);
		request.setAttribute("data", data);
		request.setAttribute("page", this);
	}

	public  String getParameterValue(String name) {
		return Page.getParameterValue(request, name, encoding);
	}
	public static  String getParameterValue(HttpServletRequest request,String name) {
		return Page.getParameterValue(request, name, ENCODING_UTF8);
	}

	public static String getParameterValue(HttpServletRequest request,
			String name, String encoding) {
		if (name == null)
			return null;
		String value = request.getParameter(name);
		if (value == null)
			return null;
		if ("post".equalsIgnoreCase(request.getMethod())) {
			return value.trim();
		} else {
			try {
				return new String(value.trim().getBytes("iso8859-1"), encoding);
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
		}// .....
		return null;
	}

}