我在以下代码中得到位图 b 的 java 空异常:我该怎么办？ 为什么 getDrawingCache 函数在创建位图时不起作用； 启动操作的按钮的 onClickListener:
KaufenGListener = new OnClickListener() {
@Override
public void onClick(View v) {
Coupon coupon = null;
System.out.println("-- iv: " + couponView);
if (clickedcoup == -1) {
Toast.makeText(getActivity(), "Please select a coupon", Toast.LENGTH_SHORT).show();
} else {
for (int i = 0; i < coupons.size(); i++) {
if (clickedcoup == i) {
coupon = coupons.get(i);
}
}
String username;
Bitmap coupo = BitmapFactory.decodeResource(getResources(), R.drawable.coupon1);
Bitmap barcode = Util.generateEAN("9310779300005", getActivity(), coupo.getWidth() / 3);
// Drawable couponDraw = new
// BitmapDrawable(getResources(),b);
System.out.println("------------b : " + barcode);
if (user.address.Nachname != null) {
username = user.address.Nachname + " " + user.address.Vorname; // bla
} else {
username = "";
}
viewFlipperVino.setDisplayedChild(8);
// LayoutParams params = new LayoutParams();
// params.width=LayoutParams.MATCH_PARENT;
// params.height=(int) (params.width/1.5);
//couponView.buildDrawingCache();
couponView.setUp(coupo, barcode, coupon.Code, gutscheinName, username, coupon.Wert);
clickedcoup = -1;
String[] recipients = new String[] { "rosu_alin@ymail.com" };
String emailSubject = "Gutschein Schenken fur "+ gutscheinName;
String emailText = "Glückwunsch, Sie haben einen Gutschein für Wein & Co!!";
Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("plain/text");
intent.putExtra(Intent.EXTRA_EMAIL, recipients);
intent.putExtra(Intent.EXTRA_SUBJECT, emailSubject);
intent.putExtra(Intent.EXTRA_TEXT, emailText);
File root = Environment.getExternalStorageDirectory();
File file = new File(root, "gutschein.png");
try {
file.createNewFile();
} catch (IOException e1) {
e1.printStackTrace();
}
couponView.setDrawingCacheEnabled(true);
couponView.buildDrawingCache();
Bitmap b = couponView.getDrawingCache();
System.out.println("bitmapget drawin cache: "+couponView.getDrawingCache());
Saver.saveImg(file, b, getActivity());
try {
System.out.println("bitmap"+b);
FileOutputStream out = new FileOutputStream(file);
b.compress(Bitmap.CompressFormat.PNG, 100, out);
System.out.println("bitmap.compress"+b.compress(Bitmap.CompressFormat.PNG, 100, out));
} catch (Exception e) {
e.printStackTrace();
}
if (!file.exists() || !file.canRead()) {
Toast.makeText(getActivity(), "Befestigung Fehler", Toast.LENGTH_SHORT).show();
return;
}
Uri uri = Uri.parse("file://" + file);
intent.putExtra(Intent.EXTRA_STREAM, uri);
startActivity(Intent.createChooser(intent, "Send email..."));
}
}
};
这是扩展 View 的 CouponView 类: 公共(public)类 CouponView 扩展 View {
private Bitmap coupon, barcode;
Paint paint = new Paint();
Paint paint2 = new Paint();
Paint paint3 = new Paint();
private String name;
private String code;
private String username;
private String wert;
int w;
int h;
public CouponView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
public CouponView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public CouponView(Context context) {
super(context);
init();
}
private void init() {
paint.setColor(0xFF000000);
paint.setTextSize(7);
paint2.setColor(0xFF000000);
paint2.setTextSize(10);
paint3.setColor(0xFF000000);
paint3.setTextSize(25);
}
public void setUp(Bitmap coupon, Bitmap barcode, String code, String name, String username,String wert) {
this.coupon = coupon;
this.barcode = barcode;
this.name = name;
this.username = username;
this.code = code;
this.wert = wert;
w = coupon.getWidth();
h = coupon.getHeight();
System.out.println("height"+h);
System.out.println("width"+w);
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
System.out.println("-------------CouponView.onDraw()");
canvas.drawBitmap(coupon, 0, 0, null);
canvas.drawBitmap(barcode, w/1.61f, h/1.20f, null);
canvas.drawText("9310779300005", w/1.429f, h/1.018f, paint);
canvas.drawText("9310779300005", w/18.12f , h/1.073f, paint2);
canvas.drawText(code, w/1.8875f, h/1.073f, paint2);
canvas.drawText(username, w/11.32f, h/10.3f, paint2);
canvas.drawText(name, w/11.32f, h/5.936f, paint2);
canvas.drawText(wert, w/1.294f, h/1.641f, paint3);
}
}
按照我的逻辑，我将 couponView 的绘图缓存设置为 (true)，然后我开始构建绘图缓存。然后我启动位图 getDrawingCache()。仅此一项就可以保存我的文件。我错过了什么？ 此外，Saves.saveIMG 函数与它之后的 try catch 做同样的事情(我只是从同事那里拿来的，因为它更有条理。而且我虽然它使用 imageView 来保存，而不是位图。
public class Saver {
public static void saveImg(File pic, Bitmap picture,Context context) {
folderExists(pic);
try {
FileOutputStream out = new FileOutputStream(pic);
picture.compress(Bitmap.CompressFormat.JPEG, 100, out);
Log.i(Saver.class.toString(), " picture writed at: " + pic.getAbsolutePath());
Toast.makeText(context, "pic saved", Toast.LENGTH_SHORT).show();
} catch (Exception e) {
pic.delete();
Log.i(Saver.class.toString(), " picture writing error: " + e.getMessage());
Toast.makeText(context, "pic not saved", Toast.LENGTH_SHORT).show();
}
}
private static void folderExists(File dir) {
System.out.println("-=-=- : " + dir.getAbsolutePath());
if (!dir.getParentFile().exists()) {
dir.mkdirs();
}
}
最佳答案
不确定您的代码究竟有什么问题，但这对我来说可以从手机内存中保存和读取位图:
将Bitmap写入内存:
public void writeBitmapToMemory(String filename, Bitmap bitmap) {
FileOutputStream fos;
// Use the compress method on the Bitmap object to write image to the OutputStream
try {
fos = this.openFileOutput(filename, Context.MODE_PRIVATE);
// Writing the bitmap to the output stream
bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.close();
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
}
阅读:
public Bitmap readBitmapFromMemory(String filename) {
Bitmap defautBitmap = null;
File filePath = this.getFileStreamPath(filename);
FileInputStream fi;
try {
fi = new FileInputStream(filePath);
defautBitmap = BitmapFactory.decodeStream(fi);
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
return defautBitmap;
}
希望对您有所帮助。
关于android - 无法在手机内存中保存位图，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/11989785/