利用servlet转发技术实现统计form表单中字母次数

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 stub
		System.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servlet
		RequestDispatcher 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 stub
		doGet(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 stub
		ServletContext 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 stub
		doGet(request,response);
	}

}

5.OK,功能实现

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