Question

我正在尝试使用以下代码将IMAGEVIEW中的图片转换为Drawable而不是我的NullPointerException转换为Base64字符串，但它会导致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);。

以下是代码：

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)

这是logcat所说的：

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Answer 1

我已经修好了。 NullPointerException是由此行引起的。

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

所以我没有使用上面的代码，而是使用下面的代码。

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

Answer 2

检查它是否也有效：

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);

将Image从ImageView转换为Base64字符串

2 个答案: