我如何将从图像URL获取的图像保存到SD卡中?
我如何将从图像URL获取的图像保存到SD卡中?
首先,您必须确保您的应用程序具有写入sd卡的权限。为此,您需要在应用程序清单文件中添加“写外部存储”权限。请参见设置 Android 权限
然后,您可以将 URL 下载到 sd 卡上的文件中。一个简单的方法是:
URL url = new URL ("file://some/path/anImage.png");
InputStream input = url.openStream();
try {
//The sdcard directory e.g. '/sdcard' can be used directly, or
//more safely abstracted with getExternalStorageDirectory()
File storagePath = Environment.getExternalStorageDirectory();
OutputStream output = new FileOutputStream (new File(storagePath,"myImage.png"));
try {
byte[] buffer = new byte[aReasonableSize];
int bytesRead = 0;
while ((bytesRead = input.read(buffer, 0, buffer.length)) >= 0) {
output.write(buffer, 0, bytesRead);
}
} finally {
output.close();
}
} finally {
input.close();
}
编辑: 在清单文件中添加权限。
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
getExternalStorageDirectory()
。你知道它返回一个尾随斜杠吗?例如/sdcard
或/sdcard/
。 - AkuseteEnvironment.getExternalStorageDirectory()
不返回一个字符串,因此你的代码无法编译。我已经为你纠正了代码。 - Jeff Axelrod关于提高性能的多线程技术,可以在 Android 开发者博客的最新文章中找到一个很好的例子:
static Bitmap downloadBitmap(String url) {
final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
final HttpGet getRequest = new HttpGet(url);
try {
HttpResponse response = client.execute(getRequest);
final int statusCode = response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
Log.w("ImageDownloader", "Error " + statusCode +
" while retrieving bitmap from " + url);
return null;
}
final HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream inputStream = null;
try {
inputStream = entity.getContent();
final Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
return bitmap;
} finally {
if (inputStream != null) {
inputStream.close();
}
entity.consumeContent();
}
}
} catch (Exception e) {
// Could provide a more explicit error message for IOException or
// IllegalStateException
getRequest.abort();
Log.w("ImageDownloader", "Error while retrieving bitmap from " + url,
e.toString());
} finally {
if (client != null) {
client.close();
}
}
return null;
}