HTTP Status 500 – Internal Server Error

web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">

  <display-name>FirstServlet</display-name>

  <welcome-file-list>

    <welcome-file>index.html</welcome-file>

    <welcome-file>index.htm</welcome-file>

    <welcome-file>index.jsp</welcome-file>

    <welcome-file>default.html</welcome-file>

    <welcome-file>default.htm</welcome-file>

    <welcome-file>default.jsp</welcome-file>

  </welcome-file-list>

  <!--FirstServlet文件  -->

  <!--声明servlet  -->

  <servlet>

      <!--Servlet名称  -->

      <servlet-name>first</servlet-name>

      <!--Servlet文件目录  -->

      <servlet-class>com.imooc.servlet.FirstServlet</servlet-class>

  </servlet>

  <!-- 将servlet与URL绑定 -->

  <servlet-mapping>

      <!--<servlet-name>配置的是与<servlet-mapping>对应的Servlet名称  -->

      <servlet-name>first</servlet-name>

      <!--用于配置Servlet的映射地址  访问路径localhost:8080/FirstServlet/hi?name=qqq -->

      <url-pattern>/hi</url-pattern>

  </servlet-mapping>

  <!--Servlet15文件  -->

  <!-- 声明servlet -->

  <servlet>

        <servlet-name>Servlet15</servlet-name>

        <servlet-class>com.imooc.servlet.Servlet15</servlet-class>   

  </servlet>

  <!-- 将servlet与URL绑定 -->

  <servlet-mapping>

        <servlet-name>Servlet15</servlet-name>

        <url-pattern>/Servlet15</url-pattern>

  </servlet-mapping>

</web-app>

Servlet15.java

package com.imooc.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class Servlet15 extends HttpServlet{

             public void service(HttpServletRequest request,HttpServletResponse response) {

                      String StringFiveteen= request.getParameter("15");

                      int IntFiveteen=Integer.parseInt(StringFiveteen);//字符串转换为整数

                      String html="<h1 style='color:red'>"+IntFiveteen+"</h1>";

                      try {

PrintWriter out=response.getWriter();

out.println(html);

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

             }

}