Java 无内容套接字编程的android图像接收

我创建了一个应用程序，通过套接字编程将图像从服务器（桌面）发送到客户端（android）……问题是我在客户端（android）获取文件，但没有内容

谁能告诉我有什么问题吗

客户端（Android）

---

查看代码，我发现您希望接收一个文件，将其保存到外部存储器并返回该文件的位图。我想这就是你想要做的，但是你的代码，事实上，并没有做到这一点。如果需要，可以使用以下代码来完成该任务。首先，服务器发送4个字节，指示文件大小，然后是文件内容；客户端读取这4个字节，然后读取整个文件，并将读取的每个块保存到磁盘。最后，它将接收到的文件转换为位图并返回

客户端代码：

public Bitmap receiveFile(InputStream is) throws Exception
    {
        String baseDir = Environment.getExternalStorageDirectory().getAbsolutePath();
        String fileName = "myFile.png";
        String imageInSD = baseDir + File.separator + fileName;
        System.out.println("FILE----------------->" + imageInSD);

        // read first 4 bytes containing the file size
        byte[] bSize = new byte[4];
        is.read(bSize, 0, 4);

        int filesize;
        filesize = (int) (bSize[0] & 0xff) << 24 | 
                   (int) (bSize[1] & 0xff) << 16 | 
                   (int) (bSize[2] & 0xff) << 8 | 
                   (int) (bSize[3] & 0xff);

        int bytesRead;
        // You may but don't have to read the whole file in memory
        // 8k buffer is good enough
        byte[] data = new byte[8 * 1024];
        int bToRead;
        FileOutputStream fos = new FileOutputStream(imageInSD);
        BufferedOutputStream bos = new BufferedOutputStream(fos);
        while (filesize > 0)
        {
            // EDIT: just in case there is more data in the stream. 
            if (filesize > data.length) bToRead=data.length;
            else bToRead=filesize;
            bytesRead = is.read(data, 0, bToRead);
            if (bytesRead > 0)
            {
                bos.write(data, 0, bytesRead);
                filesize -= bytesRead;
            }
        }
        bos.close();
        // I guess you want to return the received image as a Bitmap
        Bitmap bmp = null;
        FileInputStream fis = new FileInputStream(imageInSD);
        try
        {
            bmp = BitmapFactory.decodeStream(fis);
        }
        catch (Exception e)
        {
            // in case of an error set it to null
            bmp = null;
        }
        finally
        {
            fis.close();
        }
        return bmp;
    }

---

在Java中复制流的正确方法如下：

while ((count = in.read(buffer)) > 0)
{
   out.write(buffer, 0, count);
}

目前，您的代码：

假设

read（）

填充缓冲区。Javadoc中没有这样的内容

忽略

read（）

返回的结果，该结果除了是非常宝贵的计数外，还可能是-1表示EOS

浪费地将缓冲区分配为文件的整个大小

假定文件大小适合

int

依赖于接收者神奇地知道传入文件的大小

---

上面的代码不做任何这些假设，并且可以使用从1开始的任何缓冲区大小。

只需滚动浏览，但您在行中读取的

是.read（data，0，data.length）

，但不使用在其中读取的字节数（不应该进入

索引
）？问题可能在于
索引+=文件大小
应该是
index+=bytesread也考虑前面的注释。这个代码不起作用。您需要限制读取长度，以便永远不会读取超过
filesize
。此外，所有的位移位都应该使用
DataOutputStream.writeLong（）
和
DataInputStream.readLong（）。
public Bitmap receiveFile(InputStream is) throws Exception
    {
        String baseDir = Environment.getExternalStorageDirectory().getAbsolutePath();
        String fileName = "myFile.png";
        String imageInSD = baseDir + File.separator + fileName;
        System.out.println("FILE----------------->" + imageInSD);

        // read first 4 bytes containing the file size
        byte[] bSize = new byte[4];
        is.read(bSize, 0, 4);

        int filesize;
        filesize = (int) (bSize[0] & 0xff) << 24 | 
                   (int) (bSize[1] & 0xff) << 16 | 
                   (int) (bSize[2] & 0xff) << 8 | 
                   (int) (bSize[3] & 0xff);

        int bytesRead;
        // You may but don't have to read the whole file in memory
        // 8k buffer is good enough
        byte[] data = new byte[8 * 1024];
        int bToRead;
        FileOutputStream fos = new FileOutputStream(imageInSD);
        BufferedOutputStream bos = new BufferedOutputStream(fos);
        while (filesize > 0)
        {
            // EDIT: just in case there is more data in the stream. 
            if (filesize > data.length) bToRead=data.length;
            else bToRead=filesize;
            bytesRead = is.read(data, 0, bToRead);
            if (bytesRead > 0)
            {
                bos.write(data, 0, bytesRead);
                filesize -= bytesRead;
            }
        }
        bos.close();
        // I guess you want to return the received image as a Bitmap
        Bitmap bmp = null;
        FileInputStream fis = new FileInputStream(imageInSD);
        try
        {
            bmp = BitmapFactory.decodeStream(fis);
        }
        catch (Exception e)
        {
            // in case of an error set it to null
            bmp = null;
        }
        finally
        {
            fis.close();
        }
        return bmp;
    }

public void send(OutputStream os) throws Exception
{
    // sendfile
    File myFile = new File("C:/div.png");
    System.out.println("the file is read");
    int fSize = (int) myFile.length();
    byte[] bSize = new byte[4];
    bSize[0] = (byte) ((fSize & 0xff000000) >> 24);
    bSize[1] = (byte) ((fSize & 0x00ff0000) >> 16);
    bSize[2] = (byte) ((fSize & 0x0000ff00) >> 8);
    bSize[3] = (byte) (fSize & 0x000000ff);

    // send 4 bytes containing the filesize
    os.write(bSize, 0, 4);

    byte[] mybytearray = new byte[(int) fSize];
    FileInputStream fis = new FileInputStream(myFile);
    BufferedInputStream bis = new BufferedInputStream(fis);
    int bRead = bis.read(mybytearray, 0, mybytearray.length);
    System.out.println("Sending...");
    os.write(mybytearray, 0, bRead);
    os.flush();
    bis.close();
}

while ((count = in.read(buffer)) > 0)
{
   out.write(buffer, 0, count);
}