如何在上传到服务器之前压缩图像

Question

public int uploadFile(String sourceFileUri) {
        int screenHeight = 800;
        int screenWidth = 600;
        HttpURLConnection conn = null;
        DataOutputStream dos = null;
        String lineEnd = "\r\n";
        String twoHyphens = "--";
        String boundary = "*****";
        int bytesRead, bytesAvailable, bufferSize;
        byte[] buffer;
        int maxBufferSize = 1 * 1024 * 1024;
        File sourceFile = new File(sourceFileUri);
        String fileName = sourceFile.getAbsolutePath();
        Log.d("file path",sourceFile.toString());
        if (!sourceFile.isFile()) {
            dialog.dismiss();
            Log.e("uploadFile", "Source File not exist :" +imagePath);
            return 0;
        }
        else
        {
            try {
                upLoadServerUri = "http://192.168.3.40:8090/PHP/fileUpload.php";
                // open a URL connection to the Servlet
                FileInputStream fileInputStream = new FileInputStream(sourceFile);
                URL url = new URL(upLoadServerUri);

                // Open a HTTP  connection to  the URL
                conn = (HttpURLConnection) url.openConnection();
                conn.setDoInput(true); // Allow Inputs
                conn.setDoOutput(true); // Allow Outputs
                conn.setUseCaches(false); // Don't use a Cached Copy
                conn.setRequestMethod("POST");
                conn.setRequestProperty("Connection", "Keep-Alive");
                conn.setRequestProperty("ENCTYPE", "multipart/form-data");
                conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
                conn.setRequestProperty("uploaded_file", fileName);

                dos = new DataOutputStream(conn.getOutputStream());

                dos.writeBytes(twoHyphens + boundary + lineEnd);
                dos.writeBytes("Content-Disposition: form-data; name=\"uploaded_file\";filename="+ fileName + "" + lineEnd);
                dos.writeBytes(lineEnd);

                // create a buffer of  maximum size
                bytesAvailable = fileInputStream.available();

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

                // read file and write it into form...
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);

                while (bytesRead > 0) {

                    dos.write(buffer, 0, bufferSize);
                    bytesAvailable = fileInputStream.available();
                    bufferSize = Math.min(bytesAvailable, maxBufferSize);
                    bytesRead = fileInputStream.read(buffer, 0, bufferSize);

                }

                // send multipart form data necesssary after file data...
                dos.writeBytes(lineEnd);
                dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

                // Responses from the server (code and message)
                serverResponseCode = conn.getResponseCode();
                String serverResponseMessage = conn.getResponseMessage();

                Log.i("uploadFile", "HTTP Response is : "+ serverResponseMessage + ": " + serverResponseCode);

                if(serverResponseCode == 200){

                    runOnUiThread(new Runnable() {
                        public void run() {

                            Toast.makeText(PreviewImage.this, "File Upload Complete.",
                                    Toast.LENGTH_SHORT).show();
                        }
                    });
                }

                //close the streams //
                fileInputStream.close();
                dos.flush();
                dos.close();

            } catch (MalformedURLException ex) {

                dialog.dismiss();
                ex.printStackTrace();

                runOnUiThread(new Runnable() {
                    public void run() {

                        Toast.makeText(PreviewImage.this, "MalformedURLException",
                                Toast.LENGTH_SHORT).show();
                    }
                });

                Log.e("Upload file to server", "error: " + ex.getMessage(), ex);
            } catch (Exception e) {

                dialog.dismiss();
                e.printStackTrace();

                runOnUiThread(new Runnable() {
                    public void run() {

                        Toast.makeText(PreviewImage.this, "Got Exception : see logcat ",
                                Toast.LENGTH_SHORT).show();
                    }
                });
                Log.e("Upload file to server Exception", "Exception : "
                        + e.getMessage(), e);
            }
            return serverResponseCode;

        } // End else block
    }

这段代码可以很好地上传图片到服务器。但我想在上传前压缩图像。我用这个代码位图 resizedbitmap=Bitmap.createScaledBitmap(bitmap, screenWidth, screenHeight, true); 但它不起作用。如何解决这个问题。

Answer 1

如果您使用的是 .png 文件，那么您可以尝试下面的代码。

ByteArrayOutputStream out = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);

此处 100 是图像质量，您可以在 0 到 100 之间更改它以获得低分辨率图像。

Answer 2

您可以使用下面的压缩方式bitmap

对于 jpeg 图片

Bitmap original = BitmapFactory.decodeStream(getAssets().open("imagg1.jpg"));
ByteArrayOutputStream out = new ByteArrayOutputStream();
original.compress(Bitmap.CompressFormat.JPEG, 100, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

以及 png 图像

Bitmap original = BitmapFactory.decodeStream(getAssets().open("imagg1.png"));
ByteArrayOutputStream out = new ByteArrayOutputStream();
original.compress(Bitmap.CompressFormat.PNG, 100, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

如何在上传到服务器之前压缩图像

How to compress image before uploading to server

android

android-image