利用servlet转发技术实现统计form表单中字母次数

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需求是利用servlet转发技术，实现对html网页中用户输入的内容进行统计，统计每个字母出现的次数，忽略大小写。其中统计功能在一个servlet中，转发功能在另一个servlet中。

1.新建dynamic web project，命名为CounterCharacter

2.在webContent目录中新建index.html文件，设置form表单

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><body><form action="/CountCharacter/LetterCountServlet" method="post">请输入文章<textarea rows="5" cols="50" name="content"></textarea><input type="submit" value="提交"/></form></body></html>

3.在JavaResource/src目录下新建一个包，命名为servletDemo，在该包中新建一个servlet，命名为LetterCountServlet,主要负责统计用户输入的内容中每个字母出现的次数

package servletDemo;import java.io.IOException;import javax.servlet.RequestDispatcher;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class LetterCountServlet * 统计用户输入内容中每个字母出现次数 */@WebServlet(asyncSupported = true, urlPatterns = { "/LetterCountServlet" })public class LetterCountServlet extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public LetterCountServlet() {        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 stubSystem.out.println("Servlet works");//获得form表单提交的内容String content = request.getParameter("content");//忽略大小写，把用户输入全部转换成大写content = content.toUpperCase();int[] times = new int[26];for(int i = 0; i < content.length();i++){char c = content.charAt(i);//判断C是不是字母if(Character.isLetter(c))times[c-'A']++;}//交给下一个servlet显示结果ServletContext context = getServletContext();//添加count属性context.setAttribute("count", times);//跳转至下一个servletRequestDispatcher dispatcher = context.getRequestDispatcher("/ResulstServlet");dispatcher.forward(request, response);}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoGet(request,response);}}

4.在servletDemo包中新建一个servlet，命名为ResultServlet，主要负责统计结果的输出

package servletDemo;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class ResulstServlet * 显示统计结果 */@WebServlet(asyncSupported = true, urlPatterns = { "/ResulstServlet" })public class ResulstServlet extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public ResulstServlet() {        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 stubServletContext context = getServletContext();int[] times = (int[]) context.getAttribute("count");//输出结果response.setContentType("text/html;charset=utf-8");PrintWriter out = response.getWriter();for(int i = 0; i < times.length;i++){char c = (char) ('A'+ i);int frequency = times[i];out.println("字母："+c+"，出现次数"+frequency+"次！<br/>");}}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoGet(request,response);}}

5.OK,功能实现

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