Servlet表单Get和Post读取

男娘i 2021-09-30 07:52 340阅读 0赞

新建一个maven的war工程，如果没有web.xml新增一个web.xml或者拷贝一个例如：

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
             xmlns="http://java.sun.com/xml/ns/javaee" 
             xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
             version="2.5">
    
    </web-app>

工程代码结构如图所示：

![1077977-20171227163841472-203042566.png][]

pom.xml添加相关依赖:

<project xmlns="http://maven.apache.org/POM/4.0.0" 
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
      <modelVersion>4.0.0</modelVersion>
      <groupId>servlet</groupId>
      <artifactId>servlet</artifactId>
      <version>1.0.0</version>
      <packaging>war</packaging>
      
      <dependencies>
        <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
          </dependency>
      </dependencies>
    </project>

## 一、HelloWorld入门示例 ##

java代码如下：

package servlet.enter;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class ServletEnter extends HttpServlet{
    
        private static final long serialVersionUID = -876565140384532446L;
        
        private String message;
        
        public void init() throws ServletException{        
            message="HelloWorld!";        
        }
        
        public void doGet(HttpServletRequest request,HttpServletResponse response)
            throws ServletException,IOException{
            response.setContentType("text/html");
            
            PrintWriter out=response.getWriter();
            out.println("<h1>"+message+"</h1>");
        }
        
        public void destroy(){
            
        }
    }

web.xml配置如下：

<servlet>
        <servlet-name>ServletEnter</servlet-name>
        <servlet-class>servlet.enter.ServletEnter</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>ServletEnter</servlet-name>
        <url-pattern>/ServletEnter</url-pattern>
      </servlet-mapping>

若是报以下错误，多半是Servlet-class的路径没有配对。重新修改下即可。

![1077977-20171227161322128-339519854.png][]

## 二、Get方式获取表单数据 ##

java代码如下：

package servlet.form;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    @WebServlet("/GetFormServlet")
    public class GetFormServlet extends HttpServlet {
        
        private static final long serialVersionUID = 1L;
        
        public GetFormServlet() {    
            super();
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            response.setContentType("text/html;charset=UTF-8");
            
            PrintWriter out=response.getWriter();
            String title="使用Get方法读取表单信息";
            String name= new String(request.getParameter("name").getBytes("ISO8859-1"),"UTF-8");
            String docType="<!DOCTYPE html> \n";
            out.println(docType+
                    "<html>\n" +
                    "<head><title>" + title + "</title></head>\n" +
                    "<body bgcolor=\"#f0f0f0\">\n" +
                    "<h1 align=\"center\">" + title + "</h1>\n" +
                    "<ul>\n" +
                    "  <li><b>站点名</b>："
                    + name + "\n" +
                    "  <li><b>网址</b>："
                    + request.getParameter("url") + "\n" +
                    "</ul>\n" +
                    "</body></html>");
        }
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doGet(request, response);
        }
    
    }

可以通过 @WebServlet("/GetFormServlet")来配置Servlet路径，这样就不要在web.xml里头配置Servlet了。
    Servlet通过request.getParameter来获取参数，当参数为中文的时候，要注意乱码处理

String name= new String(request.getParameter("name").getBytes("ISO8859-1"),"UTF-8");

Servlet 处理表单数据，这些数据会根据不同的情况使用不同的方法自动解析：

getParameter()：您可以调用 request.getParameter() 方法来获取表单参数的值。
    getParameterValues()：如果参数出现一次以上，则调用该方法，并返回多个值，例如复选框。
    getParameterNames()：如果您想要得到当前请求中的所有参数的完整列表，则调用该方法。

地址栏输入：

http://localhost:8081/servlet/GetFormServlet?name=shawWey&url=www.shawwey.com

浏览器效果如图：

![1077977-20171227163022753-769122302.png][]

## 三、Post方式获取表单数据 ##

java 代码如下：

package servlet.form;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    @WebServlet("/PostFormServlet")
    public class PostFormServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;
           
        public PostFormServlet() {
            super();
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            response.setContentType("text/html;charset=UTF-8");
            PrintWriter out=response.getWriter();
            String title="使用Post方法读取表单信息";
            String name= new String(request.getParameter("name").getBytes("ISO8859-1"),"UTF-8");
            String docType="<!DOCTYPE html> \n";
            out.println(docType+
                    "<html>\n" +
                    "<head><title>" + title + "</title></head>\n" +
                    "<body bgcolor=\"#f0f0f0\">\n" +
                    "<h1 align=\"center\">" + title + "</h1>\n" +
                    "<ul>\n" +
                    "  <li><b>站点名</b>："
                    + name + "\n" +
                    "  <li><b>网址</b>："
                    + request.getParameter("url") + "\n" +
                    "</ul>\n" +
                    "</body></html>");
        }
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doGet(request, response);
        }
    
    }

页面html代码如下：

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="utf-8">
    <title>测试教程</title>
    </head>
    <body>
    <form action="PostFormServlet" method="GET">
    网址名：<input type="text" name="name">
    <br />
    网址：<input type="text" name="url" />
    <input type="submit" value="提交" />
    </form>
    </body>
    </html>

浏览器效果：

![1077977-20171227163352660-1577685637.png][]       ![1077977-20171227163340128-222257094.png][]

##  四、另一个表单实例 ##

java代码如下：

package servlet.form;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.Enumeration;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class Form extends HttpServlet {
        private static final long serialVersionUID = 1L;
           
        public Form() {
            super();
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 设置响应内容类型
            response.setContentType("text/html;charset=UTF-8");
            PrintWriter out = response.getWriter();
            String title = "读取所有的表单数据";
            String docType =
                "<!doctype html public \"-//w3c//dtd html 4.0 " +
                "transitional//en\">\n";
                out.println(docType +
                "<html>\n" +
                "<head><meta charset=\"utf-8\"><title>" + title + "</title></head>\n" +
                "<body bgcolor=\"#f0f0f0\">\n" +
                "<h1 align=\"center\">" + title + "</h1>\n" +
                "<table width=\"100%\" border=\"1\" align=\"center\">\n" +
                "<tr bgcolor=\"#949494\">\n" +
                "<th>参数名称</th><th>参数值</th>\n"+
                "</tr>\n");
    
            Enumeration paramNames = request.getParameterNames();
    
            while(paramNames.hasMoreElements()) {
                String paramName = (String)paramNames.nextElement();
                out.print("<tr><td>" + paramName + "</td>\n");
                String[] paramValues =
                request.getParameterValues(paramName);
                // 读取单个值的数据
                if (paramValues.length == 1) {
                    String paramValue = paramValues[0];
                    if (paramValue.length() == 0)
                        out.println("<td><i>没有值</i></td>");
                    else
                        out.println("<td>" + paramValue + "</td>");
                } else {
                    // 读取多个值的数据
                    out.println("<td><ul>");
                    for(int i=0; i < paramValues.length; i++) {
                    out.println("<li>" + paramValues[i]);
                }
                    out.println("</ul></td>");
                }
                out.print("</tr>");
            }
            out.println("\n</table>\n</body></html>");
        }
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doGet(request, response);
        }
    
    }

配置web.xml

<servlet>
        <description></description>
        <display-name>Form</display-name>
        <servlet-name>Form</servlet-name>
        <servlet-class>servlet.form.Form</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>Form</servlet-name>
        <url-pattern>/Form</url-pattern>
      </servlet-mapping>

html页面代码如下：

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="utf-8">
    <title>菜鸟教程(runoob.com)</title>
    </head>
    <body>
    
    <form action="Form" method="POST" target="_blank">
    <input type="checkbox" name="maths" checked="checked" /> 数学
    <input type="checkbox" name="physics"  /> 物理
    <input type="checkbox" name="chemistry" checked="checked" /> 化学
    <input type="submit" value="选择学科" />
    </form>
    
    </body>
    </html>

本文代码示例： [代码下载][Link 1]

转载于:https://www.cnblogs.com/shawWey/p/8126492.html

[1077977-20171227163841472-203042566.png]: /images/20210725/a55bc4b006e64013a62dcadb3faa95e2.png
[1077977-20171227161322128-339519854.png]: /images/20210725/12a8a3ae42f54713bc3284bc952213f7.png
[1077977-20171227163022753-769122302.png]: /images/20210725/d63d2e581f6647bb95b48e3de5efc829.png
[1077977-20171227163352660-1577685637.png]: https://images2017.cnblogs.com/blog/1077977/201712/1077977-20171227163352660-1577685637.png
[1077977-20171227163340128-222257094.png]: /images/20210725/087b7df8f1ec49c38a987856fb2c2e97.png
[Link 1]: http://download.csdn.net/download/qiwei31229/10176265