使用 OkHTTP 客户端下载二进制文件损坏

Question

我正在尝试使用 OkHttp 下载二进制文件并取得进展。
当 BUFFER_SIZE 为 1.
时，文件可以正确下载但是，当我将 BUFFER_SIZE 设置为 1024 时，文件会损坏。
BUFFER_SIZE 设置为 1 文件需要很长时间才能下载

下面是代码片段：

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

import okhttp3.Call;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class DownloadTest {

    public static String url = "https://cdn.pixabay.com/photo/2017/02/06/12/34/reptile-2042906_1280.jpg";

    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        Call call = client.newCall(new Request.Builder().url(url).get().build());
        Response response = call.execute();

        System.out.println("" + response.headers().toString());
        System.out.println("" + response.body().contentLength());
        InputStream inputStream = response.body().byteStream();

        float contentLength = (float) response.body().contentLength();

        OutputStream fileOutputStream = new FileOutputStream(new File("myfile.jpg"));

        System.out.println("writing file " + contentLength);

        float downloaded = 0;

        /**
         * IF BUFFER_SIZE IS 1 file is downloaded properly
         * if BUFFER_SIZE is 1024 file is corrupted
         * open the downloaded image to test
         */
        //byte[] BUFFER_SIZE = new byte[1]; //Proper Download
        byte[] BUFFER_SIZE = new byte[1024]; //File Corrupt



        while (true) {
            int byteRead = inputStream.read(BUFFER_SIZE);
            if (byteRead == -1) {
                break;
            }

            downloaded += byteRead;

            fileOutputStream.write(BUFFER_SIZE);

            System.out.println(" " + downloaded + "/" + contentLength + " = " + ((downloaded / contentLength) * 100));

        }
        fileOutputStream.flush();
        fileOutputStream.close();

        System.out.println("file closed");
    }

}

Answer 1

您的代码有点混乱，因为 BUFFER_SIZE 看起来像一个数字常量。除此之外，我认为你的问题是fileOutputStream.write(BUFFER_SIZE)。在最后一次写入时，当您的 byte[] 不是 "full," 时，您仍将写入数组的全部内容。使用指定偏移量 (0) 和要写入的字节 (byteRead.)

的重载

Answer 2

如果您的 BUFFER_SIZE 在上次读取时未满，那么您将在文件中写入错误数据：

你有

fileOutputStream.write(BUFFER_SIZE);

你应该有：

fileOutputStream.write(BUFFER_SIZE, 0, byteRead);

EDIT1：我还建议替换这部分代码：

while (true) {
  int byteRead = inputStream.read(BUFFER_SIZE);
  if (byteRead == -1) {
    break;
  }

采用更好的方法：

int byteRead;
while ( (byteRead = inputStream.read(BUFFER_SIZE)) > 0 ) {

使用 OkHTTP 客户端下载二进制文件损坏

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