将ImageView中的图像转换为Base64字符串

Question

我正在尝试使用以下代码将不在我的Drawable中的IMAGEVIEW图像转换为Base64字符串，但它导致NullPointerException。

这是代码：

ImageView iv1 = (ImageView)findViewById(R.id.imageView1);
iv1.buildDrawingCache();
Bitmap bmap = iv1.getDrawingCache();
ByteArrayOutputStream bos = new ByteArrayOutputStream();  
bmap.compress(CompressFormat.PNG,100,bos); 
byte[] bb = bos.toByteArray();
String image = Base64.encodeBytes(bb);

这里是logcat的内容：

04-30 11:38:23.233: E/AndroidRuntime(17284): FATAL EXCEPTION: main
04-30 11:38:23.233: E/AndroidRuntime(17284): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.imageurl/com.example.imageurl.MainActivity}: java.lang.NullPointerException
04-30 11:38:23.233: E/AndroidRuntime(17284):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at android.app.ActivityThread.access$600(ActivityThread.java:130)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at android.os.Handler.dispatchMessage(Handler.java:99)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at android.os.Looper.loop(Looper.java:137)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at android.app.ActivityThread.main(ActivityThread.java:4745)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at java.lang.reflect.Method.invokeNative(Native Method)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at java.lang.reflect.Method.invoke(Method.java:511)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at  com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
04-30 11:38:23.233: E/AndroidRuntime(17284):    at dalvik.system.NativeStart.main(Native Method)
 04-30 11:38:23.233: E/AndroidRuntime(17284): Caused by: java.lang.NullPointerException
 04-30 11:38:23.233: E/AndroidRuntime(17284):   at com.example.imageurl.MainActivity.onCreate(MainActivity.java:59)
 04-30 11:38:23.233: E/AndroidRuntime(17284):   at android.app.Activity.performCreate(Activity.java:5008)
 04-30 11:38:23.233: E/AndroidRuntime(17284):   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
 04-30 11:38:23.233: E/AndroidRuntime(17284):   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)

- test test

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这行代码在MainActivity.java文件的第59行是什么？ - RajaReddy PolamReddy

Answer 1

我已经修复了它。NullPointerException是由这行代码引起的。

iv1.buildDrawingCache();
Bitmap bmap = iv1.getDrawingCache();

所以，我没有使用上述代码，而是使用了下面的代码。

BitmapDrawable drawable = (BitmapDrawable) iv.getDrawable();
Bitmap bitmap = drawable.getBitmap();

- test test

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如果您已解决了问题，请将您的答案标记为正确并关闭问题。 - GrIsHu

Answer 2

检查一下，它也可以工作：

iv1.buildDrawingCache();
Bitmap bitmap = iv1.getDrawingCache();

ByteArrayOutputStream stream=new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 90, stream);
byte[] image=stream.toByteArray();
System.out.println("byte array:"+image);

String img_str = Base64.encodeToString(image, 0);
System.out.println("string:"+img_str);

- SubbaReddy PolamReddy