使用Java提交HTML表单数据以从jsp应用程序中检索下载 [英] Submit HTML form data using Java to retrieve a download from a jsp application

问题描述

我有一个模糊的问题。我正在将一些Perl移植到Java的过程中，并且Perl代码中的一种方法发布到一个jsp应用程序并下载一个zip文件。 Perl代码的工作部分如下，它似乎使用get来检索文件。

  $ mech-> ; get（$ url）; 
 $ mech-> submit_form（
 fields => {
 upload => variable1，
 selectValue => variable2，
}，
 ）; 
  

jsp页面如下：

 <！DOCTYPE HTML PUBLIC -  // W3C // DTD HTML 4.01 Transitional // EN> 
< html> 
< head> 
< meta http-equiv =Content-Typecontent =text / html; charset = ISO-8859-1> 
< title>提取特征< / title> 
< / head> 
 
< body> 
< form action =extract.zipmethod =postenctype =multipart / form-data> 
< table> 
< tr> 
< th align =left>档案：< / th> 
< td>< input type =filename =upload>< / td> 
< / tr> 
< tr> 
< th align =left>代码：< / th> 
< td>< select name =selectValue> 
< option value =13selected =selected> 13< / option> 
< option value =14> 14< / option> 
< option value =15> 15< / option> 
< / select>< / td> 
< / tr> 
 
< tr> 
< td align =centercolspan =2>< input type =submitvalue =Submit>< / td> 
< / tr> 
< / table> 
< / form> 
< / body> 
< / html> 
  

我正在使用的Java代码尝试访问它：

  URL url = new URL（s.getUrlScheme（），s.getUrlHost（），s.getUrlFile（））; 
 String urlParameters =upload = C：\\testFile.txt& selectValue = 14; 
 HttpURLConnection连接=（HttpURLConnection）url.openConnection（）; 
 connection.setDoInput（true）; 
 connection.setDoOutput（true）; 
 connection.setInstanceFollowRedirects（false）; 
 connection.setRequestMethod（POST）; 
 connection.setRequestProperty（Content-Type，text / html）; 
 connection.setRequestProperty（charset，ISO-8859-1）; 
 connection.setRequestProperty（Content-Length，Integer.toString（urlParameters.length（）））; 
 connection.setUseCaches（false）; 
 DataOutputStream wr = new DataOutputStream（connection.getOutputStream（））; 
 wr.writeBytes（urlParameters）; 
 wr.flush（）; 
 wr.close（）; 
 InputStream is = connection.getInputStream（）; 
 OutputStream os = new FileOutputStream（。\\test.html）; 
 
 int数据; （（data = is.read（））！= -1）{
 os.write（data）; 
} 
 
 is.close（）; 
 os.close（）; 
 connection.disconnect（）; 
  

解决方案

首先抱歉，评论。我以为你试图通过提交一些值来执行简单的 POST 请求。我错过了你也在上传文件。因此，由于您还在上传文件（请注意，您不只是在此传递文件名），这是一个 mutlipart请求（您可以在您的jsp中看到： enctype = multipart / form-data），并且有更多工作可以通过编程来完成。

当您提交多部分表单时看起来像这样：

  ---------------------- ------- 253171262814565 
内容处理：表单数据; NAME = MYFILE; filename =test.bin
 Content-Type：application / octet-stream 
 
测试数据
 ---------------- ------------- 253171262814565 
 Content-Disposition：form-data; name =submit
 
提交
 ----------------------------- 253171262814565-- 
  

奇怪的字母数字称为边界（由浏览器随机选择）并用于在提交的字段（文件或普通字段）之间进行区分。在上面的例子中，提交的字段是：

• 名为myfile的字段是< input type =文件> 的形式。用户选择了名为 test.bin 的文件。文件数据是一条文本行测试数据


• Submit的正常字段值< code>< input type =submit> 按钮




下面我已经从 code.java.net上的示例，它提供了一个可以帮助您创建此类请求的类。





请修改任何硬编码的URL和文件来匹配你的情况。我没有尝试过，但它应该给你如何创建一个像上面的请求的想法。 （请注意，有两个类：一个构造请求，一个使用 main（）方法来测试它）

注意：换行字符 \r\\\
不取决于系统，但它是构建多部分请求的一部分。因此，无论您的系统是Windows还是Linux，都应该使用它。





我希望有帮助

  package net.codejava.networking; 
 
 import java.io.BufferedReader; 
 
 import java.io.File; 
 import java.io.FileInputStream; 
 import java.io.IOException; 
 import java.io.InputStreamReader; 
 import java.io.OutputStream; 
 import java.io.OutputStreamWriter; 
 import java.io.PrintWriter; 
导入java.net.HttpURLConnection; 
 import java.net.URL; 
 import java.net.URLConnection; 
 import java.util.ArrayList; 
 import java.util.List; 
 
 / ** 
 *该工具类提供了一个抽象层，用于将多部分HTTP 
 * POST请求发送到Web服务器。 
 * @author www.codejava.net 
 * 
 * / 
公共类MultipartUtility {
 private final String boundary; 
 private static final String LINE_FEED =\r\\\
; 
私有HttpURLConnection httpConn; 
私人字符串字符集; 
 private OutputStream outputStream; 
私人PrintWriter作家; 
 $ b $ ** 
 *这个构造函数初始化一个新的HTTP POST请求，其中内容类型
 *被设置为multipart / form-data 
 * @param requestURL 
 * @param charset 
 * @throws IOException 
 * / 
 public MultipartUtility（String requestURL，String charset）
 throws IOException {
 this.charset = charset; 
 
 //根据时间戳创建一个唯一边界
 boundary ====+ System.currentTimeMillis（）+===; 
 
网址url =新网址（requestURL）; 
 httpConn =（HttpURLConnection）url.openConnection（）; 
 httpConn.setDoOutput（true）; //表示POST方法
 httpConn.setDoInput（true）; 
 httpConn.setRequestProperty（Content-Type，
multipart / form-data; boundary =+ boundary）; 
 outputStream = httpConn.getOutputStream（）; 
 writer = new PrintWriter（new OutputStreamWriter（outputStream，charset），
 true）; 
} 
 $ b $ ** ** b $ b *向请求添加一个表单字段
 * @param name字段名称
 * @param值字段值
 * / 
 public void addFormField（String name，String value）{
 writer.append（ - + boundary）.append（LINE_FEED）; 
 writer.append（Content-Disposition：form-data; name = \+ name +\）
 .append（LINE_FEED）; 
 writer.append（Content-Type：text / plain; charset =+ charset）.append（
 LINE_FEED）; 
 writer.append（LINE_FEED）; 
 writer.append（value）.append（LINE_FEED）; 
 writer.flush（）; 
 
 $ b $ ** b $ b *在< input type =filename = name中为请求
 * @param fieldName name属性添加上传文件部分。 .../> 
 * @param uploadFile a要上传的文件
 * @throws IOException 
 * / 
 public void addFilePart（String fieldName，File uploadFile）
 throws IOException {
 String fileName = uploadFile.getName（）; 
 writer.append（ - + boundary）.append（LINE_FEED）; 
 writer.append（
Content-Disposition：form-data; name = \+ fieldName 
 +\; filename = \+ fileName +\\ \\）
 .append（LINE_FEED）; 
 writer.append（
Content-Type：
 + URLConnection.guessContentTypeFromName（fileName））
 .append（LINE_FEED）; 
 writer.append（Content-Transfer-Encoding：binary）。append（LINE_FEED）; 
 writer.append（LINE_FEED）; 
 writer.flush（）; 
 
 FileInputStream inputStream = new FileInputStream（uploadFile）; 
 byte [] buffer = new byte [4096]; 
 int bytesRead = -1; （（bytesRead = inputStream.read（buffer））！= -1）{
 outputStream.write（buffer，0，bytesRead）; 
 while（ 
} 
 outputStream.flush（）; 
 inputStream.close（）; 
 
 writer.append（LINE_FEED）; 
 writer.flush（）; 
} 
 
 / ** 
 *完成请求并接收来自服务器的响应。 
 * @返回一个字符串列表作为响应，以防服务器返回
 *状态OK，否则抛出异常。 
 * @throws IOException 
 * / 
 public List< String> finish（）抛出IOException {
 List< String> response = new ArrayList< String>（）; 
 
 writer.append（LINE_FEED）.flush（）; 
 writer.append（ - + boundary + - ）。append（LINE_FEED）; 
 writer.close（）; 
 
 //首先检查服务器的状态码
 int status = httpConn.getResponseCode（）; 
 if（status == HttpURLConnection.HTTP_OK）{
 BufferedReader reader = new BufferedReader（new InputStreamReader（
 httpConn.getInputStream（）））; 
 String line = null; （（line = reader.readLine（））！= null）{
 response.add（line）; 
 while 
} 
 reader.close（）; 
 httpConn.disconnect（）; 
} else {
抛出新的IOException（服务器返回的非OK状态：+状态）; 
} 
 
返回响应; 
} 
} 
 
 // ------------------------------ --------------------------- 
 
 package net.codejava.networking; 
 
 import java.io.File; 
 import java.io.IOException; 
 import java.util.List; 
 
 / ** 
 *该程序演示了MultipartUtility类的用法。 
 * @author www.codejava.net 
 * 
 * / 
 public class MultipartFileUploader {
 
 public static void main（String [] args）{ 
 String charset =UTF-8; 
文件uploadFile1 =新文件（e：/Test/PIC1.JPG）; 
文件uploadFile2 =新文件（e：/Test/PIC2.JPG）; 
 String requestURL =http：// localhost：8080 / FileUploadSpringMVC / uploadFile.do; 
 
尝试{
 MultipartUtility multipart = new MultipartUtility（requestURL，charset）; 
 multipart.addFormField（description，Cool pix）; 
 multipart.addFilePart（fileUpload，uploadFile1）; 
 multipart.addFilePart（fileUpload，uploadFile2）; 
 
列表< String> response = multipart.finish（）; 
 System.out.println（SERVER REPLIED：）; 
 for（String line：response）{
 System.out.println（line）; 
} 
} catch（IOException ex）{
 System.out.println（ERROR：+ ex.getMessage（））; 
 ex.printStackTrace（）; 
} 
} 
} 
  




I have an obscure issue. I am in the process of porting some Perl to Java and one of the methods in the Perl code posts to a jsp app and downloads a zip file. The working part of the Perl code is as follows which appears to be using a get to retrieve the file.

$mech->get ( $url );
$mech->submit_form(
fields => {
     upload => variable1,
     selectValue => variable2,
    },
);

The jsp page is as follows:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Extract Features</title>
</head>

<body>
<form action="extract.zip" method="post" enctype="multipart/form-data">
<table>
<tr>
    <th align="left">File:</th>
    <td><input type="file" name="upload"></td>
</tr>
<tr>
    <th align="left">Code:</th>
    <td><select name="selectValue">
        <option value="13" selected="selected">13</option>
        <option value="14">14</option>
        <option value="15">15</option>
    </select></td>
</tr>

<tr>
    <td align="center" colspan="2"><input type="submit" value="Submit"></td>
</tr>
</table>
</form>
</body>
</html>

And the Java code I am using to try to access it:

URL url = new URL(s.getUrlScheme(), s.getUrlHost(), s.getUrlFile());
String urlParameters = "upload=C:\\testFile.txt&selectValue=14";
HttpURLConnection connection = (HttpURLConnection)url.openConnection();
connection.setDoInput(true);
connection.setDoOutput(true);
connection.setInstanceFollowRedirects(false);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "text/html");
connection.setRequestProperty("charset", "ISO-8859-1");
connection.setRequestProperty("Content-Length", Integer.toString(urlParameters.length()));
connection.setUseCaches(false);
DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
wr.writeBytes(urlParameters);
wr.flush();
wr.close();
InputStream is = connection.getInputStream();
OutputStream os = new FileOutputStream(".\\test.html");

int data;
while ((data=is.read()) != -1) {
os.write(data);
}

is.close();
os.close();
connection.disconnect();

解决方案

First of all sorry for the example I have posted in the comment. I thought you were trying to perform a simple POST request by just submitting some values. I have missed that you were also uploading a file. So since you are also uploading a file (note that you don't just pass a filename here) this is a mutlipart request (you see that in your jsp: enctype="multipart/form-data") and it has a little more work to do that programmatically.

When you are submitting a multipart form the request looks like this:

-----------------------------253171262814565
Content-Disposition: form-data; name="myfile"; filename="test.bin"
Content-Type: application/octet-stream

Test data    
-----------------------------253171262814565
Content-Disposition: form-data; name="submit"

Submit
-----------------------------253171262814565--

That strange alphanumerics are called a boundary (are chosen randomly by the browser) and are used to distringuish between submitted fields (files or normal fields). In the above example the submitted fields were:

• a field named "myfile" that was an <input type="file"> in the form. The user selected the file named test.bin. The file data was a single text line Test data
• a normal field value of "Submit" of a <input type="submit"> button

Below I have copied the code from an example at code.java.net that provides a class that can help you in creating such requests.

Please modify any hard-coded urls and files to match your case. I have not tried it out but it should give you the idea of how to create a request like the above one. (Note that there are two classes: One that constructs the request and one with a main() method to test it)

Side note: The change of line character \r\n does not depend on the system but it is a part of how multipart requests are constructed. So you should use it as is no matter if your system is Windows or Linux

I hope that helps

package net.codejava.networking;

import java.io.BufferedReader;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;

/**
 * This utility class provides an abstraction layer for sending multipart HTTP
 * POST requests to a web server.
 * @author www.codejava.net
 *
 */
public class MultipartUtility {
    private final String boundary;
    private static final String LINE_FEED = "\r\n";
    private HttpURLConnection httpConn;
    private String charset;
    private OutputStream outputStream;
    private PrintWriter writer;

    /**
     * This constructor initializes a new HTTP POST request with content type
     * is set to multipart/form-data
     * @param requestURL
     * @param charset
     * @throws IOException
     */
    public MultipartUtility(String requestURL, String charset)
            throws IOException {
        this.charset = charset;

        // creates a unique boundary based on time stamp
        boundary = "===" + System.currentTimeMillis() + "===";

        URL url = new URL(requestURL);
        httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setDoOutput(true); // indicates POST method
        httpConn.setDoInput(true);
        httpConn.setRequestProperty("Content-Type",
                "multipart/form-data; boundary=" + boundary);
        outputStream = httpConn.getOutputStream();
        writer = new PrintWriter(new OutputStreamWriter(outputStream, charset),
                true);
    }

    /**
     * Adds a form field to the request
     * @param name field name
     * @param value field value
     */
    public void addFormField(String name, String value) {
        writer.append("--" + boundary).append(LINE_FEED);
        writer.append("Content-Disposition: form-data; name=\"" + name + "\"")
                .append(LINE_FEED);
        writer.append("Content-Type: text/plain; charset=" + charset).append(
                LINE_FEED);
        writer.append(LINE_FEED);
        writer.append(value).append(LINE_FEED);
        writer.flush();
    }

    /**
     * Adds a upload file section to the request
     * @param fieldName name attribute in <input type="file" name="..." />
     * @param uploadFile a File to be uploaded
     * @throws IOException
     */
    public void addFilePart(String fieldName, File uploadFile)
            throws IOException {
        String fileName = uploadFile.getName();
        writer.append("--" + boundary).append(LINE_FEED);
        writer.append(
                "Content-Disposition: form-data; name=\"" + fieldName
                        + "\"; filename=\"" + fileName + "\"")
                .append(LINE_FEED);
        writer.append(
                "Content-Type: "
                        + URLConnection.guessContentTypeFromName(fileName))
                .append(LINE_FEED);
        writer.append("Content-Transfer-Encoding: binary").append(LINE_FEED);
        writer.append(LINE_FEED);
        writer.flush();

        FileInputStream inputStream = new FileInputStream(uploadFile);
        byte[] buffer = new byte[4096];
        int bytesRead = -1;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
        outputStream.flush();
        inputStream.close();

        writer.append(LINE_FEED);
        writer.flush();    
    }

    /**
     * Completes the request and receives response from the server.
     * @return a list of Strings as response in case the server returned
     * status OK, otherwise an exception is thrown.
     * @throws IOException
     */
    public List<String> finish() throws IOException {
        List<String> response = new ArrayList<String>();

        writer.append(LINE_FEED).flush();
        writer.append("--" + boundary + "--").append(LINE_FEED);
        writer.close();

        // checks server's status code first
        int status = httpConn.getResponseCode();
        if (status == HttpURLConnection.HTTP_OK) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    httpConn.getInputStream()));
            String line = null;
            while ((line = reader.readLine()) != null) {
                response.add(line);
            }
            reader.close();
            httpConn.disconnect();
        } else {
            throw new IOException("Server returned non-OK status: " + status);
        }

        return response;
    }
}

//---------------------------------------------------------

package net.codejava.networking;

import java.io.File;
import java.io.IOException;
import java.util.List;

/**
 * This program demonstrates a usage of the MultipartUtility class.
 * @author www.codejava.net
 *
 */
public class MultipartFileUploader {

    public static void main(String[] args) {
        String charset = "UTF-8";
        File uploadFile1 = new File("e:/Test/PIC1.JPG");
        File uploadFile2 = new File("e:/Test/PIC2.JPG");
        String requestURL = "http://localhost:8080/FileUploadSpringMVC/uploadFile.do";

        try {
            MultipartUtility multipart = new MultipartUtility(requestURL, charset);
            multipart.addFormField("description", "Cool pix");
            multipart.addFilePart("fileUpload", uploadFile1);
            multipart.addFilePart("fileUpload", uploadFile2);

            List<String> response = multipart.finish();
            System.out.println("SERVER REPLIED:");
            for (String line : response) {
                System.out.println(line);
            }
        } catch (IOException ex) {
            System.out.println("ERROR: " + ex.getMessage());
            ex.printStackTrace();
        }
    }
}

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