java web基础 --- form提交

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1、servlet裸奔

2、重写了Servlet的init方法后一定要记得调用父类的init方法，否则在service/doGet/doPost方法中使用getServletContext()方法获取ServletContext对象时就会出现java.lang.NullPointerException异常

3、转码支持中文显示

myform.html

<!DOCTYPE html><html><head><meta http-equiv="content-type" content="text/html;charset=utf-8"><title>Insert title here</title></head><body><h1>表单数据提交</h1><form action="helloWorld" method="POST">姓名:<input type="text" name="name_str"/><br/><br/>职业:<input type="text" name="occyp_str"/><br/><br/>年龄:<input type="text" name="age_num"/><br/><br/><input type="submit" value="提交"/></form></body></html>

HelloWorldServlet.java

package com.web1.hello;import java.io.IOException;import java.io.PrintWriter;import java.util.Enumeration;import javax.servlet.RequestDispatcher;import javax.servlet.ServletConfig;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 HelloWorldServlet */@WebServlet("/HelloWorldServlet")public class HelloWorldServlet extends HttpServlet {private static final long serialVersionUID = 1L;    private String message;    /**     * @see HttpServlet#HttpServlet()     */    public HelloWorldServlet() {        super();        // TODO Auto-generated constructor stub    }/** * @see Servlet#init(ServletConfig) */public void init(ServletConfig config) throws ServletException {message = "Hello world, Servlet Example!";/*重写了Servlet的init方法后一定要记得调用父类的init方法，否则在service/doGet/doPost方法中使用getServletContext()方法获取ServletContext对象时就会出现java.lang.NullPointerException异常*/super.init(config);}/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {/*response.setContentType("text/html");PrintWriter out = response.getWriter();out.println("<h1>" +message+ "</h1>");out.close();*///最原始的页面跳转String formPage = "/pages/myform.html";RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(formPage);dispatcher.forward(request, response);}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {Enumeration<String> names = request.getParameterNames();response.setHeader("Content-type", "text/html;charset=UTF-8");response.setCharacterEncoding("UTF-8");PrintWriter writer = response.getWriter();writer.println("<h1>显示提交表单数据</h1>");while (names.hasMoreElements()) {String name = names.nextElement();writer.print("<p>");writer.print(name + " ： ");//在Tomcat中request和response的默认编码格式//为ISO-8859-1//转码成UTF-8String value = request.getParameter(name);value = new String(value.getBytes("ISO-8859-1"), "UTF-8");writer.print(value);writer.print("</p>");}writer.println("<h1>提交成功</h1>");writer.close();}@Overridepublic void destroy() {// TODO Auto-generated method stubsuper.destroy();}}

web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http;//www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/javaee                             http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"version="3.0" metadata-complete="true"><description> Hello World Servlet</description><display-name>Hello World Servlet</display-name><servlet><servlet-name>helloWorld</servlet-name><servlet-class>com.web1.hello.HelloWorldServlet</servlet-class></servlet><servlet-mapping><servlet-name>helloWorld</servlet-name><url-pattern>/helloWorld</url-pattern></servlet-mapping></web-app>

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