我在Android上尝试openCV示例。当我尝试使用以下代码将bmp文件保存到SD卡的每个线程时：
String filePath = "/sdcard"; // some times it may be only /sdcard not /mnt/sdcard
filePath += "newFileName.jpg";
try {
bmp.compress(Bitmap.CompressFormat.JPEG, 100, new FileOutputStream(new File(filePath)));
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.i(TAG, "IOException Occurred!!!");
}
日志始终显示“IOException Occurred”且SD卡上没有保存文件。
完整的班级代码在
之下public abstract class SampleCvViewBase extends SurfaceView implements SurfaceHolder.Callback, Runnable {
private static final String TAG = "Sample::SurfaceView";
private SurfaceHolder mHolder;
private VideoCapture mCamera;
private FpsMeter mFps;
public SampleCvViewBase(Context context) {
super(context);
mHolder = getHolder();
mHolder.addCallback(this);
mFps = new FpsMeter();
Log.i(TAG, "Instantiated new " + this.getClass());
}
public void surfaceChanged(SurfaceHolder _holder, int format, int width, int height) {//called immediately after the structural change of surface
Log.i(TAG, "surfaceCreated");
synchronized (this) {
if (mCamera != null && mCamera.isOpened()) {
Log.i(TAG, "before mCamera.getSupportedPreviewSizes()");
List<Size> sizes = mCamera.getSupportedPreviewSizes();
Log.i(TAG, "after mCamera.getSupportedPreviewSizes()");
int mFrameWidth = width;
int mFrameHeight = height;
// selecting optimal camera preview size
{
double minDiff = Double.MAX_VALUE;
for (Size size : sizes) {
if (Math.abs(size.height - height) < minDiff) {
mFrameWidth = (int) size.width;
mFrameHeight = (int) size.height;
minDiff = Math.abs(size.height - height);
}
}
}
mCamera.set(Highgui.CV_CAP_PROP_FRAME_WIDTH, mFrameWidth);
mCamera.set(Highgui.CV_CAP_PROP_FRAME_HEIGHT, mFrameHeight);
}
}
}
public void surfaceCreated(SurfaceHolder holder) {
Log.i(TAG, "surfaceCreated");
mCamera = new VideoCapture(Highgui.CV_CAP_ANDROID);
if (mCamera.isOpened()) {
(new Thread(this)).start(); //new thread
} else {
mCamera.release();
mCamera = null;
Log.e(TAG, "Failed to open native camera");
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
Log.i(TAG, "surfaceDestroyed");
if (mCamera != null) {
synchronized (this) {
mCamera.release();
mCamera = null;
}
}
}
protected abstract Bitmap processFrame(VideoCapture capture) throws IOException;
public void run() {
Log.i(TAG, "Starting processing thread"); //send out log notice
mFps.init(); //instance of Fps meter
while (true) {
Bitmap bmp = null;
synchronized (this) {
if (mCamera == null) //instance of video capture
break;
if (!mCamera.grab()) {
Log.e(TAG, "mCamera.grab() failed");
break;
}
try {
bmp = processFrame(mCamera);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mFps.measure();
}
if (bmp != null) {
Canvas canvas = mHolder.lockCanvas();
if (canvas != null) {
canvas.drawBitmap(bmp, (canvas.getWidth() - bmp.getWidth()) / 2, (canvas.getHeight() - bmp.getHeight()) / 2, null);
mFps.draw(canvas, (canvas.getWidth() - bmp.getWidth()) / 2, 0);
mHolder.unlockCanvasAndPost(canvas);
}
String filePath = "/sdcard"; // some times it may be only /sdcard not /mnt/sdcard
filePath += "newFileName.jpg";
try {
bmp.compress(Bitmap.CompressFormat.JPEG, 100, new FileOutputStream(new File(filePath)));
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.i(TAG, "IOExcpetion Occurred!!!");
}
}
以下是我在DDMS中的内容：
03-07 08:58:11.639: W/TextLayoutCache(986): computeValuesWithHarfbuzz -- need to force to single run
03-07 08:58:11.709: W/System.err(986): java.io.FileNotFoundException: /sdcardnewFileName.jpg: open failed: EROFS (Read-only file system)
03-07 08:58:11.769: W/System.err(986): at libcore.io.IoBridge.open(IoBridge.java:406)
03-07 08:58:11.769: W/System.err(986): at java.io.FileOutputStream.<init>(FileOutputStream.java:88)
03-07 08:58:11.809: W/System.err(986): at java.io.FileOutputStream.<init>(FileOutputStream.java:73)
03-07 08:58:11.829: W/System.err(986): at org.opencv.samples.fd.SampleCvViewBase.run(SampleCvViewBase.java:125)
03-07 08:58:11.829: W/System.err(986): at org.opencv.samples.fd.FdView.run(FdView.java:107)
03-07 08:58:11.829: W/System.err(986): at java.lang.Thread.run(Thread.java:856)
03-07 08:58:11.829: W/System.err(986): Caused by: libcore.io.ErrnoException: open failed: EROFS (Read-only file system)
03-07 08:58:11.859: W/System.err(986): at libcore.io.Posix.open(Native Method)
03-07 08:58:11.859: W/System.err(986): at libcore.io.BlockGuardOs.open(BlockGuardOs.java:98)
03-07 08:58:11.889: W/System.err(986): at libcore.io.IoBridge.open(IoBridge.java:390)
03-07 08:58:11.889: W/System.err(986): ... 5 more
03-07 08:58:11.919: I/Sample::SurfaceView(986): IOExcpetion Occurred!!!
03-07 08:58:12.489: D/dalvikvm(986): GC_FOR_ALLOC freed 1209K, 14% free 9902K/11399K, paused 29ms
03-07 08:58:12.489: I/dalvikvm-heap(986): Grow heap (frag case) to 10.925MB for 1228816-byte allocation
03-07 08:58:12.619: D/dalvikvm(986): GC_CONCURRENT freed <1K, 3% free 11102K/11399K, paused 3ms+45ms
一旦检测完成一次，我就试图保存一个bmp图像。任何人都可以帮助我吗？谢谢你
答案 0 :(得分：4)
您正在尝试写入文件系统根目录，因为您错过了文件路径中的正斜杠：您使用的是/sdcardnewFileName.jpg而不是/sdcard/newFileName.jpg。
但你没有在那里写的权限，所以你得到一个例外。
另外：请不要像这样硬编码SD卡的路径。而是使用Environment.getExternalStorageDirectory()。某些设备将卡安装在不同的路径上或改为使用闪存。此方法始终返回正确的路径。如果您不这样做，则在跨多个设备使用您的应用时会遇到问题。
答案 1 :(得分：3)
1 /你的路上没有斜线。
2 /这不是找到SD卡路径并在其上创建文件的正确方法： http://developer.android.com/reference/android/os/Environment.html#getExternalStorageDirectory%28%29
File root = Environment.getExternalStorageDirectory();
File imgFile = new File(root, "newFileName.jpg");
FileOutputStream fos = new FileOutputStream(imgFile);