你也可以设置任何图片的背景:

View v;
Drawable image=(Drawable)getResources().getDrawable(R.drawable.img);
(ImageView)v.setBackground(image);

RelativeLayout relativeLayout;  //declare this globally

现在，在任何函数中，如onCreate, onResume

relativeLayout = new RelativeLayout(this);  
relativeLayout.setBackgroundResource(R.drawable.view); //or whatever your image is
setContentView(relativeLayout); //you might be forgetting this

你也可以设置任何图片的背景:

View v;
Drawable image=(Drawable)getResources().getDrawable(R.drawable.img);
(ImageView)v.setBackground(image);

setBackground(getContext().getResources().getDrawable(R.drawable.green_rounded_frame));

if (android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN)
     layout.setBackgroundDrawable(getResources().getDrawable(R.drawable.ready));
else if(android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP_MR1)
     layout.setBackground(getResources().getDrawable(R.drawable.ready));
else
     layout.setBackground(ContextCompat.getDrawable(this, R.drawable.ready));

试试ViewCompat。setBackground (yourView drawableBackground)