android - 如何从另一个 Activity 更改布局背景？

Question

我想在用户单击按钮时更改布局背景。根据我的项目，我有一个 MainActivity，在这个 MainActivity 中我想更改布局背景和一个 Gridview Activity ，在这个 Activity 中我有背景图像和一个全屏 Activity 显示 gridview 选择的特定图像，在这个全屏 Activity 中，我有一个名为“设置背景”的按钮来设置布局的背景。

这是我的全屏 Activity

public class FullScreenImage extends Activity{


Button setWallpaper;
Context mContext;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.layout_fullscreen_image);


    setWallpaper = (Button)findViewById(R.id.setWall);

    mContext = FullScreenImage.this;

    //Get image fro Image adapter
    final Bundle bdl = getIntent().getExtras();
    final int imageRes = bdl.getInt("imageID");
    final ImageView image = (ImageView) findViewById(R.id.imgDisplay);
    image.setImageResource(imageRes);

    setWallpaper.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

                //What is the code for changing background

        }
    });
}
}

GridView Activity

public class ChangeWallpaper extends Activity {

GridView gridImage;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.change_theme);

    gridImage = (GridView)findViewById(R.id.gridImage);
    gridImage.setAdapter(new ImageAdapter2(this));
}
}

这是我的 Imageadapter，我有背景图片

public class ImageAdapter2 extends BaseAdapter {

private Context mContext;

public ImageAdapter2() {

}

public int getCount() {
    return mThumbIds.length;
}
public Object getItem(int position) {
    return mThumbIds[position];
}
public long getItemId(int position) {
    return 0;
}
public ImageAdapter2(Context c) {
    mContext = c;
}

public View getView(final int position, View convertView, ViewGroup parent) {
    ImageView imageView;
    if (convertView == null){
        imageView = new ImageView(mContext);
        Picasso.with(mContext).load(mThumbIds[position])
                .resize(200, 200).into(imageView);
        imageView.setLayoutParams(new GridView.LayoutParams(150,150));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setPadding(3, 3, 3, 3);
        imageView.setMaxHeight(300);
        imageView.setMaxWidth(300);
        imageView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                MyPreferenceActivity myPref = new MyPreferenceActivity(mContext);
                myPref.setGifImage(position);

                Intent intent = new Intent(mContext,FullScreenImage.class);
                intent.putExtra("imageID", mThumbIds[position]);
                mContext.startActivity(intent);

            }
        });

    }
    else{
        imageView = (ImageView) convertView;
    }
    return imageView;
}
public Integer[] mThumbIds = {

        R.drawable.imagess,R.drawable.seven
};
}

这是我想更改布局背景的 MainActivity，我的布局是 LinearLayout

public class MainActivity extends ActionBarActivity {


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


  }
 }

我对图像的偏好 Activity

public class MyPreferenceActivity extends PreferenceActivity{

Context context;
public SharedPreferences sp;
SharedPreferences.Editor editor;

private final static String KEY_IMAGE = "image";

public MyPreferenceActivity(Context context)
{
    this.context = context;
    sp = context.getApplicationContext().getSharedPreferences("Image", 0);
    editor = sp.edit();
}
public void setGifImage(int imgUrl)
{
    editor.putInt(KEY_IMAGE, imgUrl);
    editor.commit();
}
public Integer getGifImage()
{
    return  sp.getInt(KEY_IMAGE, 0);
}
}

所以，如果有人知道，请提供想法。谢谢

Answer 1

如果背景的变化必须持久，您可以使用sharedpreferences，您可以在其中选择图像来更改首选项，并在onResume 的 Activity 中背景必须改变您将检查它并进行更改

否则，您可以创建一个Singleton，如果您不需要此更改是持久的，则可以执行相同的操作。

编辑

设置偏好

SharedPreferences prefs = context.getSharedPreferences("Image", 0);
SharedPreferences.Editor editor = prefs.edit(); 
editor.putString(KEY_IMAGE, imgUrl);
editor.commit(); (or .apply(); but in this case you should use commit();)

阅读

SharedPreferences prefs = context.getSharedPreferences("Image", 0);
String url = prefs.getString(KEY_IMAGE, "");

上下文是必需的，在 Activity 中，但是你在 Activity 中有它