Pagination.java

package cn.newgxu.bbs.common;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * 
 * @author polly
 * @since 4.0.0
 * @version $Revision 1.1$
 */
public class Pagination {

	private static final Log log = LogFactory.getLog(Pagination.class);

	private int offset = 5;

	private int page = 1;

	private int pageSize = Constants.DEFAULT_PAGE_SIZE;

	private int maxPage = 1;

	private int recordSize = 0;

	private String queryString = null;

	private String actionName = null;

	private String requestString = null;

	private Map<String, String[]> paramMap = new HashMap<String, String[]>();

	public Pagination() {
//		if (log.isDebugEnabled()) {
//			log.debug("Pagination=" + super.toString());
//		}
	}

	public Pagination(int page) {
		this();
		setPage(page);
	}

	public Pagination(int page, int pageSize) {
		this(page);
		setPageSize(pageSize);
	}

	public Pagination(int page, int pageSize, int recordSize) {
		this(page, pageSize);
		this.recordSize = recordSize;
	}

	public void setActionName(String actionName) {
		this.actionName = actionName;
	}

	public String getActionName() {
		if (this.actionName == null) {
			this.actionName = "/";
		}
		return this.actionName;
	}

	public int getPageSize() {
		return pageSize;
	}

	public void setPageSize(int size) {
		if (size >= 1 && size <= Constants.DEFAULT_MAX_SIZE) {
			this.pageSize = size;
		}
	}

	public int getFirst() {
		return (page - 1) * pageSize;
	}

	public int getPage() {
		if (this.page > getMaxPage()) {
			this.page = getMaxPage();
		}
		return page;
	}

	public void setPage(int page) {
		if (page < 1) {
			page = 1;
		}
		this.page = page;
	}

	public int getMaxPage() {
		this.maxPage = recordSize / pageSize;
		if (recordSize % pageSize > 0) {
			this.maxPage++;
		}

		this.maxPage = this.maxPage < 1 ? 1 : this.maxPage;

		return this.maxPage;
	}

	// public void setMaxPage(int maxPage) {
	// this.maxPage = maxPage;
	// }

	public int getRecordSize() {
		return recordSize;
	}

	public void setRecordSize(int recordSize) {
		this.recordSize = recordSize;
	}

	public Map<String, String[]> getParamMap() {
		return paramMap;
	}

	public void setParamMap(Map<String, String[]> paramMap) {
		this.paramMap = paramMap;
	}

	public void addParam(String paramName, String[] paramValues) {
		this.paramMap.put(paramName, paramValues);
	}

	public void addParam(String paramName, String paramValue) {
		addParam(paramName, new String[] { paramValue });
	}

	public boolean isFirstPage() {
		return (this.page == 1);
	}

	public boolean isLastPage() {
		return (this.page >= getMaxPage());
	}

	public boolean hasNextPage() {
		return !isLastPage();
	}

	public boolean hasPrevPage() {
		return !isFirstPage();
	}

	public boolean hasResult() {
		return recordSize > 0;
	}

	public String getQueryString() {
		if (this.queryString == null) {
			StringBuffer sb = new StringBuffer("");
			if (paramMap != null && paramMap.size() > 0) {
				for (Iterator<String> iter = paramMap.keySet().iterator(); iter
						.hasNext();) {
					String key = iter.next();
					String[] values = paramMap.get(key);
					for (int i = 0; i < values.length; i++) {
						if (!"page".equals(key)) {
							try {
								sb.append(key).append("=").append(
										URLEncoder.encode(values[i], "UTF-8"))
										.append("&");
							} catch (UnsupportedEncodingException e) {
								e.printStackTrace();
							}
						}
					}
				}
			}
			this.queryString = sb.toString();
		}
		return this.queryString;
	}

	public String getRequestString() {
		if (this.requestString == null) {
			StringBuffer sb = new StringBuffer("");
			sb.append(getActionName()).append("?").append(getQueryString());
			this.requestString = sb.toString();
		}
		return this.requestString;
	}

	public String getPageToDisplay() {
		// 如果没有结果，则不显示任何东西
		if (!hasResult()) {
			if (log.isDebugEnabled()) {
				log.debug("没有结果。recordsize=" + recordSize);
			}
			return "";
		}

		int maxPage = getMaxPage();

		StringBuffer sb = new StringBuffer();

		if (isFirstPage()) {
			sb.append("<span class=\"nextprev\">上一页  </span>");
		} else {
			sb.append("<a class=\"nextprev\" href='")
					.append(getRequestString()).append("page=").append(
							this.page - 1).append("'>").append("上一页  ").append(
							"</a>");
		}

		if (page - offset < 2) {
			// 1 2 3 4 page
			for (int i = 1; i < page; i++) {
				sb.append("<a href='").append(getRequestString()).append(
						"page=").append(i).append("'>").append("  " + i + "  ")
						.append("</a>");
			}
		} else {
			// 1...3 4 5 6 page
			sb.append("<a href='").append(getRequestString()).append("page=")
					.append(1).append("'>").append("  " + 1 + "  ").append(
							"</a>");
			sb.append("...");
			for (int i = page - offset; i < page; i++) {
				sb.append("<a href='").append(getRequestString()).append(
						"page=").append(i).append("'>").append("  " + i + "  ")
						.append("</a>");
			}
		}

		sb.append("<span class=\"current\">").append("  " + page + "  ")
				.append("</span>");

		if (page + offset + 1 > maxPage) {
			// page 7 8 9
			for (int i = page + 1; i <= maxPage; i++) {
				sb.append("<a href='").append(getRequestString()).append(
						"page=").append(i).append("'>").append("  " + i + "  ")
						.append("</a>");
			}
		} else {
			// page 7 8 9 10 ... 100
			for (int i = page + 1; i <= page + offset; i++) {
				sb.append("<a href='").append(getRequestString()).append(
						"page=").append(i).append("'>").append("  " + i + "  ")
						.append("</a>");
			}
			sb.append("<span class=\"break\">...</span>");
			sb.append("<a href='").append(getRequestString()).append("page=")
					.append(maxPage).append("'>").append("  " + maxPage + "  ")
					.append("</a>");
		}

		if (isLastPage()) {
			sb.append("<span class=\"nextprev\"> 下一页</span>");
		} else {
			sb.append("<a class=\"nextprev\" href='")
					.append(getRequestString()).append("page=").append(
							this.page + 1).append("'>").append(" 下一页").append(
							"</a>");
		}

		return sb.toString();
	}

	public String toString() {
		return this.getPageToDisplay();
	}

}