J2EE基础之通用分页02

今天我们用下面这个页面进行本篇知识点的分享：

一、分页界面代码：

该页面代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>






书籍列表



	
		
			
		
		
	

	
		
			
				书籍ID
				书籍名
				价格
			
		
		
			
				1
				圣墟第1章
				1
			
			
				1
				圣墟第1章
				1
			

		
	
	
	
		
	
	
		首页
		<
		1
		2
		3
		>
		尾页
		到第页
		确定
		共666条

书籍ID	书籍名	价格
1	圣墟第1章	1
1	圣墟第1章	1

用到前面分享的知识，反射，封装tld（如果有不明白的可以去查阅一番哈哈）

二、封装分页代码

今天分享的知识点主要是这些类：

图中的util包里的很多类在上一篇博客有分享源代码，如果小伙伴需要的话，可以去粘取

助手类：

package tag;


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 util.PageBean;

public class PageTag extends BodyTagSupport{
	private PageBean pageBean;
	
	public PageBean getPageBean() {
		return pageBean;
	}

	public void setPageBean(PageBean pageBean) {
		this.pageBean = pageBean;
	}

	@Override
	public int doStartTag() throws JspException {
		JspWriter out = pageContext.getOut();
		try {
			out.print(toHTML());
		} catch (Exception e) {
			e.printStackTrace();
		}
		return super.doStartTag();
	}

	private String toHTML() {
		StringBuffer sb =new StringBuffer();
		//隐藏的form表单，作用保存上一次查询条件
		sb.append("");
		sb.append("	");
		Map parameterMap = pageBean.getParameterMap();
		if(parameterMap != null && parameterMap.size()>0) {
			Set> entrySet = parameterMap.entrySet();
			for (Entry entry : entrySet) {
				String key =entry.getKey();//name/likes/page/rows
				String[] values = entry.getValue();
				if(!"page".equals(key)) {
					for (String value : values) {
						sb.append("	");
					}
				}
			}
		}
		sb.append("");
		//分页条
		sb.append("");
		sb.append("	);
		sb.append("		href='javascript:gotoPage(1)'>首页");
		sb.append("	);
		sb.append("		href='javascript:gotoPage("+pageBean.previousPage()+")'><");
		sb.append("	"+pageBean.getPage()+"");
		sb.append("	+pageBean.nextPage()+")'>>");
		sb.append("	+pageBean.maxPage()+")'>尾页");
		sb.append("	到第页");
		sb.append("	);
		sb.append("		href='javascript:skipPage()'>确定");
		sb.append("	共"+pageBean.getTotal()+"条");
		sb.append("");
		//分页js代码
		sb.append("");
		return sb.toString();
	}
}

booklist.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
	<%@ taglib uri="http://jsp.pengshuai.ps" prefix="p" %>
	<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>






书籍列表



	
		
			
		
		
	

	
				
		
			
				书籍ID
				书籍名
				价格
			
		
		
			
					${b.bid }
					${b.bname }
					${b.price }

书籍ID	书籍名	价格
${b.bid }	${b.bname }	${b.price }

三、自定义标签

自定义一个标签来放通用分页代码,有一个属性，我们需要把分页类引用调用分页属性,再用StringBuffer拼接分页代码来输送到页面

助手类PageTag:

package tag;


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 util.PageBean;

public class PageTag extends BodyTagSupport{
	private PageBean pageBean;
	
	public PageBean getPageBean() {
		return pageBean;
	}

	public void setPageBean(PageBean pageBean) {
		this.pageBean = pageBean;
	}

	@Override
	public int doStartTag() throws JspException {
		JspWriter out = pageContext.getOut();
		try {
			out.print(toHTML());
		} catch (Exception e) {
			e.printStackTrace();
		}
		return super.doStartTag();
	}

	private String toHTML() {
		StringBuffer sb =new StringBuffer();
		//隐藏的form表单，作用保存上一次查询条件
		sb.append("");
		sb.append("	");
		Map parameterMap = pageBean.getParameterMap();
		if(parameterMap != null && parameterMap.size()>0) {
			Set> entrySet = parameterMap.entrySet();
			for (Entry entry : entrySet) {
				String key =entry.getKey();//name/likes/page/rows
				String[] values = entry.getValue();
				if(!"page".equals(key)) {
					for (String value : values) {
						sb.append("	");
					}
				}
			}
		}
		sb.append("");
		//分页条
		sb.append("");
		sb.append("	);
		sb.append("		href='javascript:gotoPage(1)'>首页");
		sb.append("	);
		sb.append("		href='javascript:gotoPage("+pageBean.previousPage()+")'><");
		sb.append("	"+pageBean.getPage()+"");
		sb.append("	+pageBean.nextPage()+")'>>");
		sb.append("	+pageBean.maxPage()+")'>尾页");
		sb.append("	到第页");
		sb.append("	);
		sb.append("		href='javascript:skipPage()'>确定");
		sb.append("	共"+pageBean.getTotal()+"条");
		sb.append("");
		//分页js代码
		sb.append("");
		return sb.toString();
	}
}

test.tld:




    
  JSTL 1.1 core library
  JSTL core
  1.1
  p
  http://jsp.这里可以随便命名.ps

  
    
        Provides core validation features for JSTL tags.
    
    
        org.apache.taglibs.standard.tlv.JstlCoreTLV
    
  

  
    page
    tag.PageTag
    JSP
      
         pageBean 
         true 
         true

booklist

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
	<%@ taglib uri="http://jsp.pengshuai.ps" prefix="p" %>
	<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>






书籍列表



	
		
			
		
		
	

	
				
		
			
				书籍ID
				书籍名
				价格
			
		
		
			
					${b.bid }
					${b.bname }
					${b.price }

书籍ID	书籍名	价格
${b.bid }	${b.bname }	${b.price }

再进行一个赋值：

写一个servlet：

package servlet;


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

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

@WebServlet("/book/search")
public class BookServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		PageBean pageBean =new PageBean();
		pageBean.setRequest(request);
		BookDao bookDao = new BookDao();
		Book book = new Book();
		book.setBname(request.getParameter("bname"));
		try {
			List books = bookDao.list2(book, pageBean);
			request.setAttribute("books", books);
		} catch (Exception e) {
			e.printStackTrace();
		}
		
		request.setAttribute("pagebean", pageBean);
		request.getRequestDispatcher("/booklist.jsp").forward(request, response);
		
	}

}

运行结果：

在调用方法导入数据时可能会遇到乱码，这里我们可以用到之前util包里面的那个解决乱码的类：EncodingFiter

package 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;


@WebFilter("/book/*")
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();
		}
	}

}

好啦！分享的通用分页知识就到这里啦！咱们下次再见！

J2EE基础之通用分页02

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