JavaFX 在服务器端创建文件

Question

我的 javaFX 应用程序在 Web 服务器 (wamp) 上运行，客户端通过浏览器访问此应用程序。我想在服务器端创建一个 xml 文件。我怎样才能做到这一点？因为目前如果我使用例如“/Users/username/Desktop”的路径，它将在客户端桌面上创建文件。我想在服务器桌面上创建这个文件。 我在 netbeans 7.2.1 上使用 javaFX 2.2

对不起我的英语不好！谢谢！

Answer 1

看起来 wamp 是一个基于 php 的服务器。在这种情况下，服务器组件将需要一些 php 脚本来处理上传。 w3schools has a sample script for uploading via php（我不认可这个脚本，因为我从未使用过它，也没有使用过 php - 我只是提供它作为参考）。

文件上传的 w3schools 教程使用 html 将文件数据发布到服务器。使用 JavaFX，您将改为使用 Java 对文件发布进行编码。 JavaFX 客户端中的 Java 部分将需要使用多部分表单 post 将文件从客户端发送到服务器。 apache httpclient 之类的东西可以做到这一点。这篇文章中有端到端解决方案的示例代码：How to upload a file using Java HttpClient library working with PHP。

Answer 2

您的 JavaFX 应用程序需要与您的 Web 服务进行通信。在这种情况下，我认为它是您网站上的一个简单表格。为此，您的客户端需要使用 GET（不太灵活）或 POST（更灵活）方法来上传稍后将由您的 PHP 脚本处理的文件。

正如jewelsea 所建议的，Apache HttpClient 可以为您完成这项工作。但是，如果您像我一样不喜欢为简单的事情添加依赖项，您可能会决定卷起袖子，像我一样实现 HttpPost 类：

/**
 * Project: jlib
 * Version: $Id: HttpPost.java 463 2012-09-17 10:58:04Z dejan $
 * License: Public Domain
 * 
 * Authors (in chronological order):
 *   Dejan Lekic - http://dejan.lekic.org
 * Contributors (in chronological order):
 *   -
 */

package co.prj.jlib;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * A class that uses HttpURLConnection to do a HTTP post. 
 * 
 * The main reason for this class is to have a simple solution for uploading files using the PHP file below:
 * 
 * Example:
 * 
 * <pre>
 *  <?php
 *  // In PHP versions earlier than 4.1.0, $HTTP_POST_FILES should be used instead
 *  // of $_FILES.
 *
 *  $uploaddir = '/srv/www/lighttpd/example.com/files/';
 *  $uploadfile = $uploaddir . basename($_FILES['userfile']['name']);
 *
 *  echo '<pre>';
 *  if (move_uploaded_file($_FILES['userfile']['tmp_name'], $uploadfile)) {
 *      echo "File is valid, and was successfully uploaded.\n";
 *      } else {
 *          echo "Possible file upload attack!\n";
 *      }
 *
 *      echo 'Here is some more debugging info:';
 *      print_r($_FILES);
 *
 *      print "</pre>";
 *  }        
 *  ?>
 *
 * </pre>
 * 
 * TODO:
 *   - Add support for arbitrary form fields.
 *   - Add support for more than just one file.
 *   - Allow for changing of the boundary
 * 
 * @author dejan
 */
public class HttpPost {
    private final String crlf = "\r\n";
    private URL url;
    private URLConnection urlConnection;
    private OutputStream outputStream;
    private InputStream inputStream;
    private String[] fileNames;
    private String output;
    private String boundary;
    private final int bufferSize = 4096;

    public HttpPost(URL argUrl) {
        url = argUrl;
        boundary = "---------------------------4664151417711";
    }

    public void setFileNames(String[] argFiles) {
        fileNames = argFiles;
    }

    public void post() {
        try {
            System.out.println("url:" + url);
            urlConnection = url.openConnection();
            urlConnection.setDoOutput(true);
            urlConnection.setDoInput(true);
            urlConnection.setUseCaches(false);
            urlConnection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);

            String postData = "";
            String fileName = fileNames[0];
            InputStream fileInputStream = new FileInputStream(fileName);

            byte[] fileData = new byte[fileInputStream.available()];
            fileInputStream.read(fileData);

            // ::::: PART 1 :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
            String part1 = "";
            part1 += "--" + boundary + crlf;
            File f = new File(fileNames[0]);
            fileName = f.getName(); // we do not want the whole path, just the name
            part1 += "Content-Disposition: form-data; name=\"userfile\"; filename=\"" + fileName + "\"" 
                    + crlf;

            // CONTENT-TYPE
            // TODO: add proper MIME support here
            if (fileName.endsWith("png")) {
                part1 += "Content-Type: image/png" + crlf;
            } else {
                part1 += "Content-Type: image/jpeg" + crlf;
            }

            part1 += crlf;
            System.out.println(part1);
            // File's binary data will be sent after this part

            // ::::: PART 2 :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
            String part2 = crlf + "--" + boundary + "--" + crlf;



            System.out.println("Content-Length" 
                    +  String.valueOf(part1.length() + part2.length() + fileData.length));
            urlConnection.setRequestProperty("Content-Length", 
                    String.valueOf(part1.length() + part2.length() + fileData.length));


            // ::::: File send ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
            outputStream = urlConnection.getOutputStream();
            outputStream.write(part1.getBytes());

            int index = 0;
            int size = bufferSize;
            do {
                System.out.println("wrote " + index + "b");
                if ((index + size) > fileData.length) {
                    size = fileData.length - index;
                }
                outputStream.write(fileData, index, size);
                index += size;
            } while (index < fileData.length);
            System.out.println("wrote " + index + "b");

            System.out.println(part2);
            outputStream.write(part2.getBytes());
            outputStream.flush();

            // ::::: Download result into the 'output' String :::::::::::::::::::::::::::::::::::::::::::::::
            inputStream = urlConnection.getInputStream();
            StringBuilder sb = new StringBuilder();
            char buff = 512;
            int len;
            byte[] data = new byte[buff];
            do {

                len = inputStream.read(data);

                if (len > 0) {
                    sb.append(new String(data, 0, len));
                }
            } while (len > 0);
            output = sb.toString();

            System.out.println("DONE");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            System.out.println("Close connection");
            try {
                outputStream.close();
            } catch (Exception e) {
                System.out.println(e);
            }
            try {
                inputStream.close();
            } catch (Exception e) {
                System.out.println(e);
            }
        }
    } // post() method

    public String getOutput() {
        return output;
    }

    public static void main(String[] args) {
        // Simple test, let's upload a picture
        try {
            HttpPost httpPost = new HttpPost(new URL("http://www.example.com/file.php"));
            httpPost.setFileNames(new String[]{ "/home/dejan/work/ddn-100x46.png" });
            httpPost.post();
            System.out.println("=======");
            System.out.println(httpPost.getOutput());
        } catch (MalformedURLException ex) {
            Logger.getLogger(HttpPost.class.getName()).log(Level.SEVERE, null, ex);
        }
    } // main() method

} // HttpPost class

如您所见，有很多地方需要改进。该类使用 HttpURLConnection 并使用 POST 方法上传文件。我用它来上传图片到我的一个网站。