如何在 Android 上保存具有自定义质量级别的 JPEG 图像

发布于 2024-10-10 04:49:04 字数 512 浏览 7 评论 0原文

在 Android 上,如何将图像文件保存为 30% 质量的 JPEG?

在标准 Java 中,我将使用 ImageIO 将图像读取为 BufferedImage,然后使用 IIOImage 实例将其保存为 JPEG 文件:< a href="http://www.universalwebservices.net/web-programming-resources/java/adjust-jpeg-image-compression-quality-when- saving-images-in-java" rel="noreferrer">http: //www.universalwebservices.net/web-programming-resources/java/adjust-jpeg-image-compression-quality-when- saving-images-in-java。然而,Android 似乎缺少 javax.imageio 包。

On Android, how do I save an image file as a JPEG at 30% quality?

In standard Java, I would use ImageIO to read the image as a BufferedImage, then save it as a JPEG file using an IIOImage instance: http://www.universalwebservices.net/web-programming-resources/java/adjust-jpeg-image-compression-quality-when-saving-images-in-java. It appears, however, that Android lacks the javax.imageio package.

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评论(4

与君绝 2024-10-17 04:49:04

您可以通过调用 compress 并设置第二个参数来以 JPEG 格式存储位图:


    Bitmap bm2 = createBitmap();
    OutputStream stream = new FileOutputStream("/sdcard/test.jpg");
    /* Write bitmap to file using JPEG and 80% quality hint for JPEG. */
    bm2.compress(CompressFormat.JPEG, 80, stream);

You can store your bitmap in the JPEG format by calling compress and setting the second parameter:


    Bitmap bm2 = createBitmap();
    OutputStream stream = new FileOutputStream("/sdcard/test.jpg");
    /* Write bitmap to file using JPEG and 80% quality hint for JPEG. */
    bm2.compress(CompressFormat.JPEG, 80, stream);

甜`诱少女 2024-10-17 04:49:04
InputStream in = new FileInputStream(file);
try {
    Bitmap bitmap = BitmapFactory.decodeStream(in);
    File tmpFile = //...;
    try {
        OutputStream out = new FileOutputStream(tmpFile);
        try {
            if (bitmap.compress(CompressFormat.JPEG, 30, out)) {
                { File tmp = file; file = tmpFile; tmpFile = tmp; }
                tmpFile.delete();
            } else {
                throw new Exception("Failed to save the image as a JPEG");
            }
        } finally {
            out.close();
        }
    } catch (Throwable t) {
        tmpFile.delete();
        throw t;
    }
} finally {
    in.close();
}
InputStream in = new FileInputStream(file);
try {
    Bitmap bitmap = BitmapFactory.decodeStream(in);
    File tmpFile = //...;
    try {
        OutputStream out = new FileOutputStream(tmpFile);
        try {
            if (bitmap.compress(CompressFormat.JPEG, 30, out)) {
                { File tmp = file; file = tmpFile; tmpFile = tmp; }
                tmpFile.delete();
            } else {
                throw new Exception("Failed to save the image as a JPEG");
            }
        } finally {
            out.close();
        }
    } catch (Throwable t) {
        tmpFile.delete();
        throw t;
    }
} finally {
    in.close();
}
往日 2024-10-17 04:49:04

@Phyrum Tea 很好,只是别忘了关闭所有东西

InputStream in = new FileInputStream(context.getFilesDir() + "image.jpg");
Bitmap bm2 = BitmapFactory.decodeStream(in);
OutputStream stream = new FileOutputStream(String.valueOf(
        context.getFilesDir() + pathImage + "/" + idPicture + ".jpg"));
bm2.compress(Bitmap.CompressFormat.JPEG, 50, stream);
stream.close();
in.close();

@Phyrum Tea is good only do not forget close everything

InputStream in = new FileInputStream(context.getFilesDir() + "image.jpg");
Bitmap bm2 = BitmapFactory.decodeStream(in);
OutputStream stream = new FileOutputStream(String.valueOf(
        context.getFilesDir() + pathImage + "/" + idPicture + ".jpg"));
bm2.compress(Bitmap.CompressFormat.JPEG, 50, stream);
stream.close();
in.close();
清风夜微凉 2024-10-17 04:49:04

使用 Kotlin 将 path 中的文件保存到 tmpPath

Files.newInputStream(path).use { inputStream ->
    Files.newOutputStream(tmpPath).use { tmpOutputStream ->
        BitmapFactory
            .decodeStream(inputStream)
            .compress(Bitmap.CompressFormat.JPEG, 30, tmpOutputStream)
    }
}

编辑:确保检查解码失败(并返回 null)的可能性以及压缩实际工作的可能性(布尔返回类型)。

    val success: Boolean = Files.newInputStream(path).use { inputStream ->
        Files.newOutputStream(tmpPath).use { tmpOutputStream ->
            BitmapFactory
                .decodeStream(inputStream)
                ?.compress(Bitmap.CompressFormat.JPEG, config.qualityLevel, tmpOutputStream)
                ?: throw Exception("Failed to decode image")
        }
    }

    if (!success) {
        throw Exception("Failed to compress and save image")
    }

Using Kotlin to save a file in path to tmpPath:

Files.newInputStream(path).use { inputStream ->
    Files.newOutputStream(tmpPath).use { tmpOutputStream ->
        BitmapFactory
            .decodeStream(inputStream)
            .compress(Bitmap.CompressFormat.JPEG, 30, tmpOutputStream)
    }
}

Edit: make sure you check for the possibility of the decode failing (and returning null) and also that compress actually worked (boolean return type).

    val success: Boolean = Files.newInputStream(path).use { inputStream ->
        Files.newOutputStream(tmpPath).use { tmpOutputStream ->
            BitmapFactory
                .decodeStream(inputStream)
                ?.compress(Bitmap.CompressFormat.JPEG, config.qualityLevel, tmpOutputStream)
                ?: throw Exception("Failed to decode image")
        }
    }

    if (!success) {
        throw Exception("Failed to compress and save image")
    }
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