如何使用 Apache HttpClient 4 获取文件上传的进度条？

我有以下用于使用 Apache 的 HTTP-Client (org.apache.http.client) 上传文件的代码：

  public static void main(String[] args) throws Exception
  {
    String fileName = "test.avi";
    File file = new File(fileName);

    String serverResponse = null;
    HttpParams params = new BasicHttpParams();
    params.setParameter(HttpProtocolParams.USE_EXPECT_CONTINUE, true);
    HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
    HttpClient client = new DefaultHttpClient(params);
    HttpPut put = new HttpPut("http://localhost:8080/" + fileName);

    FileEntity fileEntity = new FileEntity(file, "binary/octet-stream");
    put.setEntity(fileEntity);   

    HttpResponse response = client.execute(put);
    HttpEntity entity = response.getEntity();
    if (entity != null)
    {
      serverResponse = EntityUtils.toString(entity);
      System.out.println(serverResponse);
    }
  }

它工作得很好，但现在我想要一个进度条来显示文件上传的进度。这是怎么做到的呢？我在以下位置找到了一个代码片段使用Java上传文件（带进度条） https://stackoverflow.com/questions/254719/file-upload-with-java-with-progress-bar但它是为 Apache HTTP Client 3 (org.apache.commons.httpclient) 设计的，并且 Apache HTTP Client 4 中不存在 RequestEntity 类。;(

也许你们有人有办法？

许多问候

Benny

我引入了一个派生FileEntity只计算写入的字节数。 它用OutputStreamProgress进行实际计数（有点像装饰者到实际的OutputStream).

The 优势这个（以及一般的装饰）是我做的not需要复制实际的实现，例如从文件流到输出流的实际复制。我还可以更改为使用不同的（更新的）实现，例如NFileEntity.

Enjoy...

文件实体.java

public class FileEntity extends org.apache.http.entity.FileEntity {

    private OutputStreamProgress outstream;

    public FileEntity(File file, String contentType) {
        super(file, contentType);
    }

    @Override
    public void writeTo(OutputStream outstream) throws IOException {
        this.outstream = new OutputStreamProgress(outstream);
        super.writeTo(this.outstream);
    }

    /**
     * Progress: 0-100
     */
    public int getProgress() {
        if (outstream == null) {
            return 0;
        }
        long contentLength = getContentLength();
        if (contentLength <= 0) { // Prevent division by zero and negative values
            return 0;
        }
        long writtenLength = outstream.getWrittenLength();
        return (int) (100*writtenLength/contentLength);
    }
}

OutputStreamProgress.java

public class OutputStreamProgress extends OutputStream {

    private final OutputStream outstream;
    private volatile long bytesWritten=0;

    public OutputStreamProgress(OutputStream outstream) {
        this.outstream = outstream;
    }

    @Override
    public void write(int b) throws IOException {
        outstream.write(b);
        bytesWritten++;
    }

    @Override
    public void write(byte[] b) throws IOException {
        outstream.write(b);
        bytesWritten += b.length;
    }

    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        outstream.write(b, off, len);
        bytesWritten += len;
    }

    @Override
    public void flush() throws IOException {
        outstream.flush();
    }

    @Override
    public void close() throws IOException {
        outstream.close();
    }

    public long getWrittenLength() {
        return bytesWritten;
    }
}