Android8修改壁纸

方法一

替换资源文件 需要重新编译
frameworks/base/core/res/res/drawable-nodpi/default_wallpaper.png

方法二

添加属性 不重新编译

public class WallpaperManager {

    /** {@hide} */
    private static final String PROP_WALLPAPER = "ro.config.wallpaper";
    /** {@hide} */
    private static final String PROP_LOCK_WALLPAPER = "ro.config.lock_wallpaper";
    /** {@hide} */
    private static final String PROP_WALLPAPER_COMPONENT = "ro.config.wallpaper_component";

    ....    

        /**
     * Open stream representing the default static image wallpaper.
     *
     * If the device defines no default wallpaper of the requested kind,
     * {@code null} is returned.
     *
     * @hide
     */
    public static InputStream openDefaultWallpaper(Context context, @SetWallpaperFlags int which) {
        final String whichProp;
        final int defaultResId;
        if (which == FLAG_LOCK) {
            /* Factory-default lock wallpapers are not yet supported
            whichProp = PROP_LOCK_WALLPAPER;
            defaultResId = com.android.internal.R.drawable.default_lock_wallpaper;
            */
            return null;
        } else {
            whichProp = PROP_WALLPAPER;
            defaultResId = com.android.internal.R.drawable.default_wallpaper;
        }
        final String path = SystemProperties.get(whichProp);
        if (!TextUtils.isEmpty(path)) {
            final File file = new File(path);
            if (file.exists()) {
                try {
                    //返回属性设置的壁纸流
                    return new FileInputStream(file);
                } catch (IOException e) {
                    // Ignored, fall back to platform default below
                }
            }
        }
        try {
            return context.getResources().openRawResource(defaultResId);
        } catch (NotFoundException e) {
            // no default defined for this device; this is not a failure
        }
        return null;
    }


}

如果有设置属性,优先返回属性设置的壁纸路径
没有设置属性,则返回默认

/system/build.prop下添加
　ro.config.wallpaper=/system/wallpaper.png

将图片放到/system/下,文件名为:wallpaper.png