文件下载-内存不足(OOM)

Question

/**
 * The size of the chunks that an file is split when writing to server.<br />
 * 1024 * 1024 -> 1mb
 */
private static final int CHUNK_SIZE = 1024 * 1024;

File output = new File(sdCardPath, fileName);
FileOutputStream fileOutputStream = null;
try {
fileOutputStream = new FileOutputStream(output);
} catch (FileNotFoundException e) {
e.printStackTrace();
}

int offset = 0;

// compute the number of chunks of 1 mb for downloading the file
// by parts
int parts = tmpFileSize / CHUNK_SIZE;
ByteString readingfile = null;
long progressUpdate = 0;

for (int partsCounter = 0; partsCounter < parts + 1; partsCounter++) {
    try {
        readingfile = serviceApi
                .readFile(
                        session,
                        filehandle, offset, CHUNK_SIZE);

        byte[] bytesRead = readingfile.toByteArray();
        int numberOfBytesReaded = bytesRead.length;
        offset = offset + numberOfBytesReaded;
        progress.publish(""
                + (int) ((progressUpdate * 100) / tmpFileSize));
        progressUpdate += numberOfBytesReaded;
        fileOutputStream.write(bytesRead, 0,
                numberOfBytesReaded);

    } catch (IOException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

try {
    if (null != fileOutputStream) {
        fileOutputStream.flush();
        fileOutputStream.close();
    }
} catch (IOException e) {
    e.printStackTrace();
}

基于@ari答案的解决方案我已经更新了代码。现在它被优化到只使用1MB（我不知道这是否是将进程分成块的最佳方式，但现在它似乎得到了改进，并且不提供OOM）。我将尝试通过检测可以使用多少堆内存来进一步优化它，但我不确定是否可以实现这一点。直到比这似乎是最好的选择。再次感谢@Ari。

Answer 1

您有许多不需要的缓冲区。

1. byte[]br=readingfile.tobytearray（）；用于获取numberofbytesreaded.
2. 然后再次获得数组:inputstream=...readingfile.tobytearray（））；并将其复制到第三个缓冲区
3. 字节数据[]=新字节[bufferSize]；.

尝试对所有这些操作只使用一个。

for (int partsCounter = 0; partsCounter < parts + 1; partsCounter++) {
    readingfile = serviceApi.readFile(session, filehandle, offset,
            (int) bufferSize);
    byte[] br = readingfile.toByteArray();
    int numberOfBytesReaded = br.length;
    offset = offset + numberOfBytesReaded;

    try {
            progress.publish(""
                    + (int) ((progressUpdate * 100) / tmpFileSize));
            progressUpdate += numberOfBytesReaded;
            fileOutputStream.write(br, 0, numberOfBytesReaded);
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}