JSP应用的自我理解之三：JSP+Servlet实现表单验证

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示例说明：通过一个表单提交页面提交给Servlet，Servlet获取信息，经过处理后，将信息存入request对象中，如果用户提交姓名为空，将重新返回登录首页，否则，把提交的信息全部显示出来

下面具体实现了~~

1、新建一个Dynamic WEB工程，名为formtt

2、新建一个登录界面index.jsp，完成登录界面的编写，具体代码如下：

<%@ page language="java" contentType="text/html; charset=GBK"    pageEncoding="GBK"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=GBK"><title>表单提交</title></head><body><br/><form id="form1" name="form1" method="post" action="test">  <p align="center"><strong>表单提交</strong></p>  <table width="331" height="147" border="1" align="center" cellpadding="0" cellspacing="0">    <tr>      <td width="76" height="35">username：</td>      <td width="183"><label>        <input type="text" name="name" id="textfield"  height="20"/>      </label></td>      <td width="50"> </td>    </tr>    <tr>      <td>sex：</td>      <td><input type="radio" name="sex" value="boy"/>boy<input type="radio" name="sex"  value="girl"/>girl</td>      <td> </td>    </tr>    <tr>      <td>address：</td>      <td><input type="text" name="address" id="textfield3" height="20"/></td>      <td> </td>    </tr>    <tr>      <td>likes：</td>      <td><label>      <input type="checkbox" name="likes" id="checkbox" value="sing" />sing      <input type="checkbox" name="likes" id="checkbox2"  value="dance"/>dance      <input type="checkbox" name="likes" id="checkbox3"   value="game"/>game      </label></td>      <td> </td>    </tr>    <tr>      <td> </td>      <td><input name="" type="submit" value="submit" />      <input name="" type="reset" value="reset" /></td>      <td> </td>    </tr>  </table></form></body></html>

具体的界面如下：

3、在服务器端建立一个包org.luojs.servlet，然后在该包下新建一个TestServlet的Java类，完成服务器端对表单的处理

具体代码如下：

package org.luojs.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class TestServlet extends HttpServlet{public void destroy() {super.destroy();}public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {this.doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {// 获取表单信息String name = request.getParameter("name");String sex = request.getParameter("sex");String address = request.getParameter("address");String[] likes = request.getParameterValues("likes");String URL = "index.jsp";String likes2 = "";if (null != likes) {for (String string : likes) {likes2 += string + "  ";}}if (null != name && !name.equals("")) {// 把从页面获取的内容放入request中request.setAttribute("name", name);request.setAttribute("sex", sex);request.setAttribute("address", address);request.setAttribute("likes", likes2);URL = "result.jsp";}request.getRequestDispatcher(URL).forward(request, response);}public void init() throws ServletException {}}

4、配置web.xml文件

<?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">    <!-- 注册servlet信息 -->  <servlet>  <servlet-name>TestServlet</servlet-name>  <servlet-class>org.luojs.servlet.TestServlet</servlet-class>  </servlet>  <servlet-mapping>  <servlet-name>TestServlet</servlet-name>  <url-pattern>/test</url-pattern>  </servlet-mapping>  <welcome-file-list>  <welcome-file>index.jsp</welcome-file>  </welcome-file-list> </web-app>

5、跑一跑试试看，发现还行，

但输入中文文字时，出现的是乱码

所以，你要用filter监听器技术来实现中文乱码解决的问题~~

（1）在org.luojs.servlet包下新建一个CharaterEncoding的Java类，具体代码如下：

package org.luojs.servlet;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;public class CharacterEncoding implements Filter{private FilterConfig config;//此filter被释放时的回调方法public void destroy() {}//主要做过滤工作的方法//FilterChain用于调用过滤器链中的下一个过滤器public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {//获取此Filter的初始参数的值String encoding = config.getInitParameter("encoding");if(null != encoding && !"".equals(encoding)){request.setCharacterEncoding(encoding);  //设置请求数据的编码方式}         //把请求和响应对象传给过滤链中的下一个要调用的过滤器或Sevletchain.doFilter(request, response);}//些filter初始化时的回调方法//FilterConfig接口实例中封装了这个Filter的初始化参数public void init(FilterConfig config) throws ServletException {this.config = config;}}

（2）在web.xml中加入如下代码：

  <!-- 解决中文乱码问题 -->  <filter>  <filter-name>CharacterEncoding</filter-name>  <filter-class>org.luojs.servlet.CharacterEncoding</filter-class>  <init-param>  <param-name>encoding</param-name>  <param-value>GBK</param-value>  </init-param>  </filter><filter-mapping><filter-name>CharacterEncoding</filter-name><url-pattern>/*</url-pattern></filter-mapping>

然后，你再跑跑，看到中文字符了，差不多了~~

参考书目：《JSP基础与案例开发详解》，清华大学出版社

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