public class MainActivity extends Activity {        private Bitmap mWallpaper;    private TextView tv=null;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        tv=(TextView)this.findViewById(R.id.setWallPaper);        setWallPaper();            }        public void setWallPaper(){        WallpaperManager wpm = (WallpaperManager) this.getSystemService(Context.WALLPAPER_SERVICE);        InputStream is = null;        is = getStream("wallpapers/wallpaper02.jpg");        if(wpm.getWallpaperInfo()!=null){            mWallpaper = Tools.getImageFromInStream(is);            try {                wpm.setBitmap(mWallpaper);                mWallpaper.recycle();                mWallpaper = null;            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }                 }    }    public InputStream getStream(String filename) {        InputStream stream = null;        try {            stream = this.getAssets().open(getFileForDpi(filename));        } catch (IOException e) {            try {                stream = this.getAssets().open("theme/" + filename);            } catch (IOException e1) {                e1.printStackTrace();            }            e.printStackTrace();        }        return stream;    }        public String getFileForDpi(String filename) {        float mScreenScale = this.getResources().getDisplayMetrics().density;        if (mScreenScale <= 0.75f) {            Log.d("launcher", "dpi=0.75");            filename = "theme-ldpi/" + filename;        } else if (mScreenScale <= 1f) {            Log.d("launcher", "dpi=1");            filename = "theme-mdpi/" + filename;        } else if (mScreenScale <= 1.5f) {            Log.d("launcher", "dpi=1.5");            filename = "theme-hdpi/" + filename;        } else            filename = "theme-xhdpi/" + filename;        return filename;    } }

　注意：需要增加权限：<uses-permission android:name="android.permission.SET_WALLPAPER" />