servlet session管理的四种方式--一 url重写-白红宇

servlet session管理的四种方式--一 url重写

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发布时间：2019-06-12

本文共 3353 字，大约阅读时间需要 11 分钟。

servlet对于多页面共享信息提供四种方式。

1.url重写的方式

在下面的例子中，每一次请求都通过doGet方法进行“分流”。

如果在网址中含有参数city且不为空，就调用showAttribute()方法下所包含的servlet页面,如果没有该参数或该参数对应值为空，则调用mainPage()方法下的页面。

if (request.getParameter("city") != null){..............showAttribute(request, response, city, page);}esle showMainPage(request, response)

在执行showMainPage()方法中，可以通过选择选项，进行url重写

选择不同的选项，其后添加??city=london&page=1或者?city=pairs&page=1,url改写为localhost:8080/Rewrite?city=london&page=1或localhost:8080/Rewrite?city=pairs&page=1重新调用doGet方法，因为其含有city参数且不为空，不再调用showMainpage()方法，改为调用showAttribute(request, response, city, page)方法，实现了多页面共享信息的目的。

pw.println("select a city"				 + "london
"				 + "
pairs
"				 + "");

import java.io.IOException;import java.io.PrintWriter;import java.util.ArrayList;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/Rewrite")public class Rewrite extends HttpServlet {	private static final long serialVersionUID = 1L;    public Rewrite() {        super();    }        ArrayList
     
       londonAttr = new ArrayList<>(10);    ArrayList
      
        pairsAttr = new ArrayList<>(10);        public void init() throws javax.servlet.ServletException{    	for( int i = 0; i < 10; i++) {    		londonAttr.add("l " + (i+1));    	}    	    	for( int i = 0; i < 10; i++) {    		pairsAttr.add("p " + (i+1));    	}    }	protected void doGet(HttpServletRequest request, HttpServletResponse response) 			throws ServletException, IOException {		if(request.getParameter("city") != null) {			System.out.println("attribute");			String city = request.getParameter("city");			int page = 1;			int p = 1;			if (request.getParameter("page") != null){			    try {			        p = Integer.parseInt(request.getParameter("page"));			        //showAttribute(request, response, city, page);			    }catch (NumberFormatException e) {}			}			page = p;			showAttribute(request, response, city, page);		}else showMainPage(request, response);	}		public void showMainPage(HttpServletRequest request, HttpServletResponse response) 			throws ServletException, IOException{		response.setContentType("text/html");		PrintWriter pw = response.getWriter();		pw.println("
       select a city"				 + "
       london
       "				 + "
       pairs
       "				 + "");	}		public void showAttribute(HttpServletRequest request, HttpServletResponse response, String city, int page)			throws ServletException, IOException {		response.setContentType("text/html");		PrintWriter pw = response.getWriter();		pw.println("" + city +""				 + "
        
         ");		if(city.equals("london")) {			for (int i = 5 * (page-1) ; i < 5 * (page-1) + 5; i++) {				pw.println("
           "); } }else if(city.equals("pairs")) { for (int i = 5 * (page-1) ; i < 5 * (page-1) + 5; i++) { pw.println("
           "); } } pw.println("
                              " + londonAttr.get(i) + "           
                    
                     " + pairsAttr.get(i) + "           
                    
         
        
");		if(page == 1) pw.println("next
");		if(page == 2) pw.println("pass
");		pw.println("city list");		pw.println("");	}		protected void doPost(HttpServletRequest request, HttpServletResponse response) 			throws ServletException, IOException {		doGet(request, response);	}}

转载于:https://www.cnblogs.com/slowalker-lee/p/7868183.html

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