Java应用程序模拟向Servlet发送POST请求

在某些情况下，需要用Java applicatioin来模拟form，向服务器(本文以servlet为例)发送http post请求，包括提交表单域中的数据以及上传文件。如果仅仅是传递form中的数据，而不包含上传文件，那是很简单的，比如Java application可以这么写：

package com.pat.postrequestemulator;

importjava.io.BufferedReader;

importjava.io.InputStream;

importjava.io.InputStreamReader;

importjava.io.OutputStreamWriter;

importjava.net.HttpURLConnection;

importjava.net.URL;

public classPostRequestEmulator

{

public static void main(String[] args)throws Exception

{

// 服务地址

URL url = newURL("http://127.0.0.1:8080/test/upload");

// 设定连接的相关参数

HttpURLConnection connection= (HttpURLConnection) url.openConnection();

connection.setDoOutput(true);

connection.setRequestMethod("POST");

OutputStreamWriter out = newOutputStreamWriter(connection.getOutputStream(), "UTF-8");

// 向服务端发送key = value对

out.write("username=kevin&password=pass");

out.flush();

out.close();

// 获取服务端的反馈

String strLine="";

String strResponse ="";

InputStream in =connection.getInputStream();

BufferedReader reader = newBufferedReader(new InputStreamReader(in));

while((strLine =reader.readLine()) != null)

{

strResponse +=strLine +"\n";

}

System.out.print(strResponse);

}

}

服务端的servlet可以这么写：

packagecom.pat.handlinghttprequestservlet;

importjava.io.IOException;

importjava.io.PrintWriter;

importjavax.servlet.ServletException;

importjavax.servlet.http.HttpServlet;

importjavax.servlet.http.HttpServletRequest;

importjavax.servlet.http.HttpServletResponse;

public classHandlingHttpRequestServlet extends HttpServlet

{

private static final longserialVersionUID = 1L;

@Override

protected void doGet(HttpServletRequestreq, HttpServletResponse resp)

throws ServletException, IOException

{

super.doGet(req, resp);

}

@Override

protected voiddoPost(HttpServletRequest req, HttpServletResponse resp)

throwsServletException, IOException

{

String username =req.getParameter("username"); //获取username所对应的value

String password =req.getParameter("password"); //获取password所对应的value

System.out.println("Thereceived username and password is: " + username + "/" +password);

// 向请求端发回反馈信息

PrintWriter out =resp.getWriter();

out.print("OK");

out.flush();

out.close();

super.doPost(req, resp);

}

}

一切看起来都不复杂。但是如果要模拟的表单，除了要向服务器传递如上面的“key = value”这样的普通信息，同时还要上传文件，事情就复杂得多。下面详解如下：

1. 准备

玄机逸士很久没有开发web方面的应用了，所以机器上没有现成的环境，为此先要进行这方面的准备。

a) 到http://tomcat.apache.org 上下载tomcat压缩包apache-tomcat-6.0.33.zip，将其解压到指定目录即可，

如：D:\Tomcat6

b) 到http://commons.apache.org上下载用于文件上传的两个包：commons-fileupload-1.2.2-bin.zip

和commons-io-2.1-bin.zip， commons-fileupload依赖于commons-io，但在编程的过程中，

不会直接用到commons-io

c) 检查Tomcat的安装是否成功。双击D:\Tomcat6\bin目录中的startup.bat文件，就可以启动tomcat。

打开浏览器，访问http://localhost:8080/，如果出现tomcat相关的页面，则说明tomcat安装成功。

d) 在D:\Tomcat6\webapps目录下创建一个test子目录，我们等会开发的servlet就将部署在这里。在

test目录下再建立两个目录WEB-INF(必须大写)和upload，在WEB-INF下面 创建两个目录classes和lib，

同时在新建一个web.xml文件；在upload目录下，创建一个temp子目录，这些工作做完以后，test目录

下面的目录文件结构如下图所示。

其中的classes目录，用来存放将要开发的servlet，lib用来存放commons-fileupload和commons-io相关的jar包，web.xml是一些应用描述信息；upload用于存放客户端(即我们要开发的Java application)上传过来的文件，temp则用于存放上传过程中可能产生的一些临时文件。

e) 将commons-fileupload-1.2.2-bin.zip和commons-io-2.1-bin.zip解压，可以得到commons-fileupload-

1.2.2.jar和commons-io-2.1.jar，我们将这两个文件拷贝到d)中创建的lib目录中。

f) 编辑web.xml使之如下：

<?xmlversion="1.0" encoding="ISO-8859-1"?>

<!--

Licensed to the Apache Software Foundation(ASF) under one or more

contributor license agreements. See the NOTICE file distributed with

this work for additional informationregarding copyright ownership.

The ASF licenses this file to You under theApache License, Version 2.0

(the "License"); you may not usethis file except in compliance with

the License.You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreedto in writing, software

distributed under the License is distributedon an "AS IS" BASIS,

WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,either express or implied.

See the License for the specific languagegoverning permissions and

limitations under the License.

-->

<web-appxmlns="http://java.sun.com/xml/ns/javaee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/javaeehttp://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"

version="2.5">

<servlet>

<servlet-name>Hello</servlet-name>

<servlet-class>com.pat.handlinghttprequestservlet.HandlingHttpRequestServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>Hello</servlet-name>

<url-pattern>/upload</url-pattern>

</servlet-mapping>

</web-app>

这个web.xml可以先从D:\Tomcat6\webapps\examples\WEB-INF下面拷贝过来，再进行如上黑体字所示的修改即可。<servlet>标签描述的是servlet代码方面的资料，其中<servlet-name>Hello</servlet-name>是给这个servlet起一个名字Hello，它必须和下面的<servlet-mapping>中的<servlet-name>一致，该名字具体是什么可以随意写定。

<servlet-class>com.pat.handlinghttprequestservlet.HandlingHttpRequestServlet</servlet-class>说明了完整的servlet类名，即servlet的类名为HandlingHttpRequestServlet，它位于包com.pat.handlinghttprequestservlet中。

<url-pattern>/upload</url-pattern>，说明了如果客户端向“http://Web服务器的URL地址:端口号/test/upload”发出了请求，则该请求将由位于包com.pat.handlinghttprequestservlet中的HandlingHttpRequestServlet进行处理。

到此，前期准备工作结束。下面准备写代码。

2.Servlet的代码

packagecom.pat.handlinghttprequestservlet;

importjava.io.File;

importjava.io.IOException;

importjava.io.PrintWriter;

importjava.util.ArrayList;

importjavax.servlet.ServletException;

importjavax.servlet.http.HttpServlet;

importjavax.servlet.http.HttpServletRequest;

importjavax.servlet.http.HttpServletResponse;

importorg.apache.commons.fileupload.FileItem;

importorg.apache.commons.fileupload.disk.DiskFileItemFactory;

importorg.apache.commons.fileupload.servlet.ServletFileUpload;

public classHandlingHttpRequestServlet extends HttpServlet

{

private static final longserialVersionUID = 1L;

@Override

protected void doGet(HttpServletRequestreq, HttpServletResponse resp)

throws ServletException, IOException

{

super.doGet(req, resp);

}

@SuppressWarnings({"unchecked", "deprecation" })

@Override

protected voiddoPost(HttpServletRequest req, HttpServletResponse resp)

throwsServletException, IOException

{

DiskFileItemFactory factory =new DiskFileItemFactory();

String path = req.getRealPath("/upload"); //得到绝对文件夹路径，比如

// "D:\\Tomcat6\\webapps\\test\\upload"

String repositoryPath =req.getRealPath("/upload/temp"); //临时文件夹路径

factory.setRepository(newFile(repositoryPath)); // 设定临时文件夹为repositoryPath

factory.setSizeThreshold(1024* 1024); // 设定上传文件的阈值，如果上传文件大于1M，

// 就可能在repository所代 表的文件夹中产生

// 临时文件，否则直接在内存中进行处理

//System.out.println("----"+ req.getContextPath()); // 得到相对文件夹路径，比如 "/test"

// 创建一个ServletFileUpload对象

ServletFileUpload uploader =new ServletFileUpload(factory);

try

{

// 调用uploader中的parseRequest方法，可以获得请求中的相关内容，

// 即一个FileItem类型的ArrayList。FileItem是在

// org.apache.commons.fileupload中定义的，它可以代表一个文件，

// 也可以代表一个普通的form field

ArrayList<FileItem>list = (ArrayList<FileItem>)uploader.parseRequest(req);

System.out.println(list.size());

for(FileItemfileItem : list)

{

if(fileItem.isFormField()) // 如果是普通的form field

{

Stringname = fileItem.getFieldName();

Stringvalue = fileItem.getString();

System.out.println(name+ " = " + value);

}

else // 如果是文件

{

Stringvalue = fileItem.getName();

intstart = value.lastIndexOf("\\");

StringfileName = value.substring(start + 1);

// 将其中包含的内容写到path(即upload目录)下，

// 名为fileName的文件中

fileItem.write(newFile(path, fileName));

}

}

}

catch(Exception e)

{

e.printStackTrace();

}

// 向客户端反馈结果

PrintWriter out =resp.getWriter();

out.print("OK");

out.flush();

out.close();

super.doPost(req, resp);

}

}

再在classes目录建立如下目录结构com\pat\handlinghttprequestservlet，这用来代表HandlingHttpRequestServlet这个servlet所在的包名，将编译好的HandlingHttpRequestServlet.class，拷贝到这个目录下，然后启动(或者重新启动)tomcat

3.Java application的代码

package com.pat.postrequestemulator;

importjava.io.BufferedReader;

importjava.io.DataInputStream;

importjava.io.File;

import java.io.FileInputStream;

importjava.io.InputStream;

importjava.io.InputStreamReader;

importjava.io.OutputStream;

importjava.io.Serializable;

importjava.net.HttpURLConnection;

importjava.net.URL;

importjava.util.ArrayList;

public classPostRequestEmulator

{

public static void main(String[] args)throws Exception

{

// 设定服务地址

String serverUrl ="http://127.0.0.1:8080/test/upload";

// 设定要上传的普通Form Field及其对应的value

ArrayList<FormFieldKeyValuePair>ffkvp = new ArrayList<FormFieldKeyValuePair>();

ffkvp.add(newFormFieldKeyValuePair("username", "Patrick"));

ffkvp.add(newFormFieldKeyValuePair("password", "HELLOPATRICK"));

ffkvp.add(newFormFieldKeyValuePair("hobby", "Computer programming"));

// 设定要上传的文件

ArrayList<UploadFileItem>ufi = new ArrayList<UploadFileItem>();

ufi.add(newUploadFileItem("upload1", "E:\\Asturias.mp3"));

ufi.add(newUploadFileItem("upload2", "E:\\full.jpg"));

ufi.add(newUploadFileItem("upload3", "E:\\dyz.txt"));

HttpPostEmulator hpe = newHttpPostEmulator();

String response =hpe.sendHttpPostRequest(serverUrl, ffkvp, ufi);

System.out.println("Responsefrom server is: " + response);

}

}

classHttpPostEmulator

{

//每个post参数之间的分隔。随意设定，只要不会和其他的字符串重复即可。

private static final String BOUNDARY ="----------HV2ymHFg03ehbqgZCaKO6jyH";

public StringsendHttpPostRequest(String serverUrl,

ArrayList<FormFieldKeyValuePair>generalFormFields,

ArrayList<UploadFileItem>filesToBeUploaded) throws Exception

{

// 向服务器发送post请求

URL url = newURL(serverUrl/*"http://127.0.0.1:8080/test/upload"*/);

HttpURLConnection connection= (HttpURLConnection) url.openConnection();

// 发送POST请求必须设置如下两行

connection.setDoOutput(true);

connection.setDoInput(true);

connection.setUseCaches(false);

connection.setRequestMethod("POST");

connection.setRequestProperty("Connection","Keep-Alive");

connection.setRequestProperty("Charset","UTF-8");

connection.setRequestProperty("Content-Type","multipart/form-data; boundary=" + BOUNDARY);

// 头

String boundary = BOUNDARY;

// 传输内容

StringBuffer contentBody =new StringBuffer("--" + BOUNDARY);

// 尾

String endBoundary ="\r\n--" + boundary + "--\r\n";

OutputStream out =connection.getOutputStream();

// 1. 处理文字形式的POST请求

for(FormFieldKeyValuePairffkvp : generalFormFields)

{

contentBody.append("\r\n")

.append("Content-Disposition: form-data; name=\"")

.append(ffkvp.getKey() + "\"")

.append("\r\n")

.append("\r\n")

.append(ffkvp.getValue())

.append("\r\n")

.append("--")

.append(boundary);

}

String boundaryMessage1 =contentBody.toString();

out.write(boundaryMessage1.getBytes("utf-8"));

// 2. 处理文件上传

for(UploadFileItem ufi :filesToBeUploaded)

{

contentBody = newStringBuffer();

contentBody.append("\r\n")

.append("Content-Disposition:form-data; name=\"")

.append(ufi.getFormFieldName() +"\"; ") // form中field的名称

.append("filename=\"")

.append(ufi.getFileName() +"\"") //上传文件的文件名，包括目录

.append("\r\n")

.append("Content-Type:application/octet-stream")

.append("\r\n\r\n");

StringboundaryMessage2 = contentBody.toString();

out.write(boundaryMessage2.getBytes("utf-8"));

// 开始真正向服务器写文件

File file = newFile(ufi.getFileName());

DataInputStream dis= new DataInputStream(new FileInputStream(file));

int bytes = 0;

byte[] bufferOut =new byte[(int) file.length()];

bytes =dis.read(bufferOut);

out.write(bufferOut,0, bytes);

dis.close();

contentBody.append("------------HV2ymHFg03ehbqgZCaKO6jyH");

StringboundaryMessage = contentBody.toString();

out.write(boundaryMessage.getBytes("utf-8"));

//System.out.println(boundaryMessage);

}

out.write("------------HV2ymHFg03ehbqgZCaKO6jyH--\r\n".getBytes("UTF-8"));

// 3. 写结尾

out.write(endBoundary.getBytes("utf-8"));

out.flush();

out.close();

// 4. 从服务器获得回答的内容

String strLine="";

String strResponse ="";

InputStream in =connection.getInputStream();

BufferedReader reader = newBufferedReader(new InputStreamReader(in));

while((strLine =reader.readLine()) != null)

{

strResponse +=strLine +"\n";

}

//System.out.print(strResponse);

return strResponse;

}

}

classFormFieldKeyValuePair implements Serializable

{

private static final longserialVersionUID = 1L;

// The form field used for receivinguser's input,

// such as "username" in "<inputtype="text" name="username"/>"

private String key;

// The value entered by user in thecorresponding form field,

// such as "Patrick" the abovementioned formfield "username"

private String value;

public FormFieldKeyValuePair(Stringkey, String value)

{

this.key = key;

this.value = value;

}

public String getKey()

{

return key;

}

public void setKey(String key)

{

this.key = key;

}

public String getValue()

{

return value;

}

public void setValue(String value)

{

this.value = value;

}

}

classUploadFileItem implements Serializable

{

private static final longserialVersionUID = 1L;

// The form field name in a form used foruploading a file,

// such as "upload1" in "<inputtype="file" name="upload1"/>"

private String formFieldName;

// File name to be uploaded, thefileName contains path,

// such as "E:\\some_file.jpg"

private String fileName;

public UploadFileItem(StringformFieldName, String fileName)

{

this.formFieldName =formFieldName;

this.fileName = fileName;

}

public String getFormFieldName()

{

return formFieldName;

}

public void setFormFieldName(StringformFieldName)

{

this.formFieldName =formFieldName;

}

public String getFileName()

{

return fileName;

}

public void setFileName(StringfileName)

{

this.fileName = fileName;

}

}

4.运行结果

运行PostRequestEmulator之前，服务器的upload目录下的情况：

运行PostRequestEmulator后，服务器的upload目录下的情况：

PostRequestEmulator从服务端得到的反馈情况：

Response fromserver is: OK

Tomcat控制台输出：

如果上传的文件中有大于1M的情况，第二次执行PostRequestEmulator的时候，就会在temp目录中产生临时文件。

本文参考材料：

http://v.youku.com/v_show/id_XMjc0ODMxMTA4.html

http://www.iteye.com/topic/1116110(在Android中用Application模拟http post请求)

http://apps.hi.baidu.com/share/detail/46728849

http://www.eoeandroid.com/thread-22679-1-1.html

http://blog.zhaojie.me/2011/03/html-form-file-uploading-programming.html