通用分页2

1.首页在我们通用分页1博客的基础上新建Servlet

package com.hmc.web;

import java.io.IOException;
import java.util.List;
import java.util.Map;

import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.hmc.dao.BookDao;
import com.hmc.entity.Book;
import com.hmc.util.PageBean;

/**
 * Servlet implementation class BookServet
 */
@WebServlet("/BookServet")
public class BookServet extends HttpServlet implements Servlet {
	private static final long serialVersionUID = 1L;
    private BookDao bookDao=new BookDao(); 
	
    /**
     * @see HttpServlet#HttpServlet()
     */
    public BookServet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
   doPost(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stubo
   String bname=request.getParameter("bname");
   Book book=new Book();
   book.setBname(bname);
   PageBean bean=new PageBean();
  
   try {
	   bean.setRequest(request);
	List<Book> list=this.bookDao.list(book, bean);
   request.setAttribute("booklist", list);
   request.setAttribute("pagebean",bean);
  
   request.getRequestDispatcher("/book.jsp").forward(request, response);
   } catch (Exception e) {
	// TODO Auto-generated catch block
	e.printStackTrace();
}
	
	}

}

　　

 2.改造PageBen

package com.hmc.util;

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

import javax.servlet.http.HttpServletRequest;

/**
 * 分页工具类
 *
 */
public class PageBean {

	private int page = 1;// 页码

	private int rows = 10;// 页大小

	private int total = 0;// 总记录数
	
	private Map<String, String[]> paMap=new HashMap<String, String[]>();
	private String url;
	
	
   public void setRequest(HttpServletRequest request) {
	  
	   //保存上一次请求的所有参数
	   this.setPaMap( request.getParameterMap());
       this.setUrl(request.getRequestURL().toString());
       //在jsp页面来控制是否分页
       this.setPagination(request.getParameter("pagination"));
        //在jsp页面控制一页展示多少条
       this.setRows(request.getParameter("rows"));
       this.setPage(request.getParameter("page"));
   }
	 
	private void setPage(String page) {
  	this.page=StringUtils.isNotBlank(page) ? Integer.valueOf(page) : this.page;
}

	private void setPagination(String pagination) {
     this.pagination=StringUtils.isNotBlank(pagination) ? !"false".equals(pagination) : this.pagination;
     
}

	private void setRows(String rows) {
	  this.rows=StringUtils.isNotBlank(rows) ? Integer.valueOf(rows) : this.rows;
    }
  
	public Map<String, String[]> getPaMap() {
		return paMap;
	}

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

	public String getUrl() {
		return url;
	}

	public void setUrl(String url) {
		this.url = url;
	}

	private boolean pagination = true;// 是否分页

	public PageBean() {
		super();
	}

	public int getPage() {
		return page;
	}

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

	public int getRows() {
		return rows;
	}

	public void setRows(int rows) {
		this.rows = rows;
	}

	public int getTotal() {
		return total;
	}

	public void setTotal(int total) {
		this.total = total;
	}

	public void setTotal(String total) {
		this.total = Integer.parseInt(total);
	}

	public boolean isPagination() {
		return pagination;
	}

	public void setPagination(boolean pagination) {
		this.pagination = pagination;
	}

	/**
	 * 获得起始记录的下标
	 * 
	 * @return
	 */
	public int getStartIndex() {
		return (this.page - 1) * this.rows;
	}

	@Override
	public String toString() {
		return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]";
	}
 
	
	 /**
	  * 获取最大的页面数
	  * @return
	  */
	public int getMaxPage() {
		return this.total%this.rows==0 ? this.total/this.rows :(this.total/this.rows)+1;
	}
	/**
	 * 获取下一页
	 * @return
	 */
	public int getNextPage() {
		return this.page<this.getMaxPage()? this.page+1:this.page;
		
	}
	/**
	 * 获取上一页
	 * @return
	 */
   public int getPreviousPage() {
	   return this.page>1 ? this.page-1:this.page;
   }
	
}

　3　创建自定义分页标签

3.1

新建助手类PageTag.java

package com.hmc.tag;

import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;

import com.hmc.util.PageBean;

public class PageTag extends  BodyTagSupport {
	
	
	private PageBean bean;

	public PageBean getBean() {
		return bean;
	}

	public void setBean(PageBean bean) {
		this.bean = bean;
	}
	
	@Override
	public int doStartTag() throws JspException {
     JspWriter out= pageContext.getOut();
	  try {
		out.print(tohtml());
	} catch (IOException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	  return  super.doStartTag();
	}
	
	private String tohtml() {
		StringBuilder sb=new StringBuilder();
		//拼接下一次发送请求所要提交的隐藏的form表单
	   sb.append("<form id='pageBeanForm' action='"+bean.getUrl()+"' method='post'>");
	   sb.append(" <input type='hidden' name='page'>");
	  
	   Map<String, String[]> paMap = bean.getPaMap();
	   if(paMap!=null&&paMap.size()>0) {
		   Set<Entry<String, String[]>> entrySet = paMap.entrySet();
	   for (Entry<String, String[]> entry : entrySet) {
	   //上一次请求可能携带页面name=page的参数，但是改参数在前面已经单独赋值
	//为什么要单独赋值呢？因为上一次请求是第一页的数据，下一次可能是第二页，因为这前后请求page对应的值是不一样的，要单独赋值
		   if(!"page".equals(entry.getKey())) {
			for(String val:entry.getValue()) {
				sb.append("<input type='hidden' name='"+entry.getKey()+"' value='"+val+"'>");
			}
		}
	}
	   }
	   sb.append(" </form>");
	  
		//拼接分页条
	   sb.append("<div style='text-align: right; font-size: 12px;'>");
	   sb.append(" 每页"+bean.getRows()+"条，共"+bean.getTotal()+"条，第"+bean.getPage()+"页，共"+bean.getMaxPage()+"页  <a href='javascript:gotoPage(1)'>首页");
	   sb.append(" </a>  <a");
	   sb.append(" href='javascript:gotoPage("+bean.getPreviousPage()+")'>上一页</a>  <a");
	   sb.append(" href='javascript:gotoPage("+bean.getNextPage()+")'>下一页</a>  <a");
	   sb.append(" href='javascript:gotoPage("+bean.getMaxPage()+")'>尾页</a>  <input type='text'");
	   
	   sb.append(" id='skipPage'");
	   sb.append(" style='text-align: center; font-size: 12px;  50px;'>  <a");
	   sb.append(" href='javascript:skipPage()'>Go</a>");
	   sb.append(" </div>");
	   //拼接所需要的js代码
	   sb.append(" <script type='text/javascript'>");
	   sb.append(" function gotoPage(page) {");
	   sb.append("   document.getElementById('pageBeanForm').page.value = page;");
	   sb.append("    document.getElementById('pageBeanForm').submit();");
	   sb.append(" }");
	   sb.append(" function skipPage() {");
	   sb.append("   var page = document.getElementById('skipPage').value;");
	   sb.append("   if(!page || isNaN(page) || parseInt(page)<1 || parseInt(page)>"+bean.getMaxPage()+"){");
	   sb.append("    alert('请输入1~N的数字');");
	   sb.append("    return;");
	   sb.append(" }");
	   sb.append("   gotoPage(page);");
	   sb.append("}");
	   sb.append("</script>");
	   return sb.toString();
	
	}
}

　　3.2创建tld文件index.tld(要与助手类的属性一一对应)

<tag>
  <name>page</name>
  <tag-class>com.hmc.tag.PageTag</tag-class>
  <body-content>JSP</body-content>
  <attribute>
    <name>bean</name>
     <required>true</required>
     <rtexprvalue>true</rtexprvalue>
  </attribute>
  </tag>

　　

4.掉用过滤器EncodingFiter.java处理中文乱码问题

@WebFilter(urlPatterns="/*")使用的是servlet3.0注解技术。

package com.hmc.util;

import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 中文乱码处理
 * 
 */
@WebFilter(urlPatterns="/*")
public class EncodingFiter implements Filter {
	private String encoding = "UTF-8";// 默认字符集

	public EncodingFiter() {
		super();
	}

	public void destroy() {
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest req = (HttpServletRequest) request;
		HttpServletResponse res = (HttpServletResponse) response;

		// 中文处理必须放到 chain.doFilter(request, response)方法前面
		res.setContentType("text/html;charset=" + this.encoding);
		if (req.getMethod().equalsIgnoreCase("post")) {
			req.setCharacterEncoding(this.encoding);
		} else {
			Map map = req.getParameterMap();// 保存所有参数名=参数值(数组)的Map集合
			Set set = map.keySet();// 取出所有参数名
			Iterator it = set.iterator();
			while (it.hasNext()) {
				String name = (String) it.next();
				String[] values = (String[]) map.get(name);// 取出参数值[注：参数值为一个数组]
				for (int i = 0; i < values.length; i++) {
					values[i] = new String(values[i].getBytes("ISO-8859-1"),
							this.encoding);
				}
			}
		}

		chain.doFilter(request, response);
	}

	public void init(FilterConfig filterConfig) throws ServletException {
		String s = filterConfig.getInitParameter("encoding");// 读取web.xml文件中配置的字符集
		if (null != s && !s.trim().equals("")) {
			this.encoding = s.trim();
		}
	}

}

　　5.新建jsp进行测试

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@page isELIgnored="false" %>
    <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"  %>
    <%@taglib prefix="z" uri="/MyJSP" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>小说目录</h2>
	<br>

	<form action="${pageContext.request.contextPath}/BookServet"
		method="post">
		书名：<input type="text" name="bname"> <input type="submit"
			value="确定">
	</form>
	<table border="1" width="100%">
		<tr>
			<td>编号</td>
			<td>名称</td>
			<td>价格</td>
		</tr>
		<c:forEach items="${booklist }" var="b">
			<tr>
				<td>${b.bid }</td>
				<td>${b.bname }</td>
				<td>${b.price }</td>
			</tr>
		</c:forEach>
	</table>
<z:page bean="${pagebean }"></z:page>
	
</body>
</html>

　　结果如下

所有数据展示

模糊查询结果

查询所有的第二页数据

 尾页数据

 这就是一个整体的一个单表通用分页效果

主要就是将上一次查询请求再发一次
String contextPath = req.getContextPath();//根目录
String url = req.getServletPath();//请求的地址
req.getRequestURL() //获取请求全路径
Map<String, String[]> parameterMap = req.getParameterMap();//获得请求中的所有参数

  注1：不能将分页表单嵌套到其它表单中，否则不能提交表单！！！