在Android中上传大文件而不会出现内存不足错误

Posted 2023-02-24

【中文标题】在Android中上传大文件而不会出现内存不足错误

【英文标题】：Upload large file in Android without outofmemory error

【发布时间】：2012-03-26 16:33:21

【问题描述】：

我的上传代码如下：

String end = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
try 
    URL url = new URL(ActionUrl);
    HttpURLConnection con = (HttpURLConnection) url.openConnection();
    con.setDoInput(true);
    con.setDoOutput(true);
    con.setUseCaches(false);
    con.setRequestMethod("POST");
    con.setRequestProperty("Connection", "Keep-Alive");
    con.setRequestProperty("Accept", "text/*");
    con.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
    DataOutputStream ds = new DataOutputStream(con.getOutputStream());
    ds.writeBytes(twoHyphens + boundary + end);
    ds.writeBytes("Content-Disposition: form-data;" + "name=\"folder\"" + end + end);
    ds.write(SavePath.getBytes("UTF-8"));
    ds.writeBytes(end);
    ds.writeBytes(twoHyphens + boundary + end);
    ds.writeBytes("Content-Disposition: form-data;" + "name=\"Filedata\"; filename=\"");
    ds.write(FileName.getBytes("UTF-8"));
    ds.writeBytes("\"" + end);
    ds.writeBytes(end);
    FileInputStream fStream = new FileInputStream(uploadFilepath+""+FileName);
    int bufferSize = 1024;
    byte[] buffer = new byte[bufferSize];
    int length = -1;
    int pro = 0;
    while((length = fStream.read(buffer)) != -1) 
        ds.write(buffer, 0, length);
           
    ds.writeBytes(end);
    ds.writeBytes(twoHyphens + boundary + twoHyphens + end);
    fStream.close();
    ds.flush();
    InputStream is = con.getInputStream();
    int ch;
    StringBuffer b = new StringBuffer();
    while((ch = is.read()) != -1) 
        b.append((char)ch);
    
    ds.close();

catch(Exception e) 
    e.printStackTrace();

虽然小于 16 mb，但它上传成功。 但当它超过 16 mb 时，“OutOfMemory”错误显示。 如何避免内存不足错误？

【问题讨论】：

我想在 while((length = fStream.read(buffer)) != -1) 循环中每次发送 1024 个字节，但我不知道该怎么做。

brian，请参考我的回答：***.com/questions/4455006/…

嘿@brian，你能发布服务器端代码

【参考方案1】：

你尝试过使用

con.setChunkedStreamingMode(1024);

这将帮助您将数据分块为特定大小，这样您就无需将整个文件保存在内存中。

更新：

尝试使用以下方法。我使用这种方法上传一个 80 mb 的文件，没有异常。

public String sendFileToServer(String filename, String targetUrl) 
    String response = "error";
    Log.e("Image filename", filename);
    Log.e("url", targetUrl);
    HttpURLConnection connection = null;
    DataOutputStream outputStream = null;
    // DataInputStream inputStream = null;

    String pathToOurFile = filename;
    String urlServer = targetUrl;
    String lineEnd = "\r\n";
    String twoHyphens = "--";
    String boundary = "*****";
    DateFormat df = new SimpleDateFormat("yyyy_MM_dd_HH:mm:ss");

    int bytesRead, bytesAvailable, bufferSize;
    byte[] buffer;
    int maxBufferSize = 1 * 1024;
    try 
        FileInputStream fileInputStream = new FileInputStream(new File(
                pathToOurFile));

        URL url = new URL(urlServer);
        connection = (HttpURLConnection) url.openConnection();

        // Allow Inputs & Outputs
        connection.setDoInput(true);
        connection.setDoOutput(true);
        connection.setUseCaches(false);
        connection.setChunkedStreamingMode(1024);
        // Enable POST method
        connection.setRequestMethod("POST");

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

        outputStream = new DataOutputStream(connection.getOutputStream());
        outputStream.writeBytes(twoHyphens + boundary + lineEnd);

        String connstr = null;
        connstr = "Content-Disposition: form-data; name=\"uploadedfile\";filename=\""
                + pathToOurFile + "\"" + lineEnd;
        Log.i("Connstr", connstr);

        outputStream.writeBytes(connstr);
        outputStream.writeBytes(lineEnd);

        bytesAvailable = fileInputStream.available();
        bufferSize = Math.min(bytesAvailable, maxBufferSize);
        buffer = new byte[bufferSize];

        // Read file
        bytesRead = fileInputStream.read(buffer, 0, bufferSize);
        Log.e("Image length", bytesAvailable + "");
        try 
            while (bytesRead > 0) 
                try 
                    outputStream.write(buffer, 0, bufferSize);
                 catch (OutOfMemoryError e) 
                    e.printStackTrace();
                    response = "outofmemoryerror";
                    return response;
                
                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);
            
         catch (Exception e) 
            e.printStackTrace();
            response = "error";
            return response;
        
        outputStream.writeBytes(lineEnd);
        outputStream.writeBytes(twoHyphens + boundary + twoHyphens
                + lineEnd);

        // Responses from the server (code and message)
        int serverResponseCode = connection.getResponseCode();
        String serverResponseMessage = connection.getResponseMessage();
        Log.i("Server Response Code ", "" + serverResponseCode);
        Log.i("Server Response Message", serverResponseMessage);

        if (serverResponseCode == 200) 
            response = "true";
        

        String CDate = null;
        Date serverTime = new Date(connection.getDate());
        try 
            CDate = df.format(serverTime);
         catch (Exception e) 
            e.printStackTrace();
            Log.e("Date Exception", e.getMessage() + " Parse Exception");
        
        Log.i("Server Response Time", CDate + "");

        filename = CDate
                + filename.substring(filename.lastIndexOf("."),
                        filename.length());
        Log.i("File Name in Server : ", filename);

        fileInputStream.close();
        outputStream.flush();
        outputStream.close();
        outputStream = null;
     catch (Exception ex) 
        // Exception handling
        response = "error";
        Log.e("Send file Exception", ex.getMessage() + "");
        ex.printStackTrace();
    
    return response;

【讨论】：

我尝试添加到 con.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary); 行的下方，但所有文件都上传失败。跨度>

错误 java.io.FileNotFoundException: ip/web/jquery/uploader/uploadify.php 显示。

* 对于在 App Engine 中使用此出色代码的任何人：在构建 connstr 的行中，在 filename= (...name=\"uploadedfile\"; filename=...) 之前添加一个空格/跨度>

@AndroSelva：如果我想向多部分实体添加更多部分？我只是在输出流中添加换行符并添加我想要的数据？假设我想添加一个名为“json”的 json 字符串和另一个文件。

我把 setChunkedStreamingMode(1024);在我的代码中，我得到： HTTP/1.1 400 Bad RequestContent-Length: 11Content-Type: text/plainBad Request

【参考方案2】：

如果服务器接受分块模式，你可以使用

((HttpURLConnection) con).setChunkedStreamingMode(chunkLength)

否则你可以使用

((HttpURLConnection) con).setChunkedStreamingMode(0);

或

/* compute first your request content length
   contentLength = formBodyLength + yourFileSize
*/
con.setRequestProperty("Content-Length", String.valueOf(contentLength));
((HttpURLConnection) con).setFixedLengthStreamingMode(contentLength);

终于...发送你想要的东西

【参考方案3】：

bitmap=Bitmap.createScaledBitmap(bitmap, 100, 100, true);

ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream); //compress to format you want.
byte [] byte_arr = stream.toByteArray();  
String image_str = Base64.encodeBytes(byte_arr);

我尝试过的最佳方式对我来说是成功的！！！

【讨论】：

压缩方法链接：developer.android.com/reference/android/graphics/Bitmap.html

问题不是关于图像，而是关于一般文件