1.使用Fresco时，根据图片url获取缓存文件

    String imgUrl = "xxx";
    ImageRequest imageRequest = ImageRequestBuilder
            .newBuilderWithSource(Uri.parse(imgUrl))
            .build();
    CacheKey cacheKey = DefaultCacheKeyFactory
            .getInstance()
            .getEncodedCacheKey(imageRequest, Uri.parse(imgUrl));
    BinaryResource bRes = ImagePipelineFactory
            .getInstance()
            .getMainFileCache()
            .getResource(cacheKey);
    File file = ((FileBinaryResource) bRes).getFile();

2.使用Fresco时，如何实现缩放效果（PhotoView），且配合ViewPager使用

• 2.1浏览图片的页面布局文件：
  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@color/black"
  android:fitsSystemWindows="true">

    <android.support.v4.view.ViewPager
        android:id="@id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
  </RelativeLayout>
  

• 2.2Activity页面，这里只摘最关键部分（直接参考PhotoDraweeView即可）
  记得引入库：compile 'me.relex:photodraweeview:1.1.2'
  public class MyPagerAdapter extends PagerAdapter {

        public MyPagerAdapter() {
  
        }
  
        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView((View) object);
        }
  
        @Override
        public Object instantiateItem(ViewGroup view, int position) {
            final PhotoDraweeView photoDraweeView = new PhotoDraweeView(view.getContext());
            PipelineDraweeControllerBuilder controller = Fresco.newDraweeControllerBuilder();
            controller.setUri(Uri.parse(mPics.get(position)));
            controller.setOldController(photoDraweeView.getController());
            controller.setControllerListener(new BaseControllerListener<ImageInfo>() {
                @Override
                public void onFinalImageSet(String id, ImageInfo imageInfo, Animatable animatable) {
                    super.onFinalImageSet(id, imageInfo, animatable);
                    if (imageInfo == null) {
                        return;
                    }
                    photoDraweeView.update(imageInfo.getWidth(), imageInfo.getHeight());
                }
            });
            photoDraweeView.setController(controller.build());
  
            try {
                view.addView(photoDraweeView, ViewGroup.LayoutParams.MATCH_PARENT,
                        ViewGroup.LayoutParams.MATCH_PARENT);
            } catch (Exception e) {
                e.printStackTrace();
            }
  
            return photoDraweeView;
        }
  
        @Override
        public int getCount() {
            return mPics.size();
        }
  
        @Override
        public boolean isViewFromObject(View view, Object object) {
            return view.equals(object);
        }
  
        @Override
        public void restoreState(Parcelable state, ClassLoader loader) {
        }
  
        @Override
        public Parcelable saveState() {
            return null;
        }
    }
  

3.保存图片后，在系统图库能查看到

// 获取拍摄完的图片文件
File file = getCameraController().getOutputFile();
try {
    MediaStore.Images.Media.insertImage(getContentResolver(),
            file.getAbsolutePath(), file.getName(), null);
    // 通知图库更新
    context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE,
            Uri.parse("file://" + file.getAbsolutePath())));
} catch (FileNotFoundException e) {
    e.printStackTrace();
}

4.跳转到应用自己的设置页面（针对request权限时被忽略情况）

Intent localIntent = new Intent();
localIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
if (Build.VERSION.SDK_INT >= 9) {
    localIntent.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
    localIntent.setData(Uri.fromParts("package", getPackageName(), null));
} else if (Build.VERSION.SDK_INT <= 8) {
    localIntent.setAction(Intent.ACTION_VIEW);
    localIntent.setClassName("com.android.settings", "com.android.settings.InstalledAppDetails");
    localIntent.putExtra("com.android.settings.ApplicationPkgName", getPackageName());
}
startActivity(localIntent);

5.获取在线视频封面（第一帧图像）

public static Bitmap getVideoBitmap(String url) {
    Bitmap bitmap = null;
    //MediaMetadataRetriever 是android中定义好的一个类，提供了统一的接口，用于从输入的媒体文件中取得帧和元数据；
    MediaMetadataRetriever retriever = new MediaMetadataRetriever();
    try {
        //根据文件路径获取缩略图
        retriever.setDataSource(url, new HashMap<String, String>());
        //获得第一帧图片
        bitmap = retriever.getFrameAtTime(0, MediaMetadataRetriever.OPTION_NEXT_SYNC);
    } catch (IllegalArgumentException e) {
        e.printStackTrace();
    } finally {
        retriever.release();
    }
    return bitmap;
}

6.Android Studio 中多个module统一support版本

在build.gradle中加入如下代码：

示例.png

configurations.all {
    resolutionStrategy.eachDependency { DependencyResolveDetails details ->
        def requested = details.requested
        if (requested.group == 'com.android.support') {
            if (!requested.name.startsWith("multidex")) {
                details.useVersion '25.4.0'
            }
        }
    }
}

7.通过代码暂停系统闹钟

startActivity(new Intent(AlarmClock.ACTION_SNOOZE_ALARM));
// 一般能查到的需要的系统权限就是这个，但是并不是
<uses-permission android:name="android.permission.SET_ALARM"/>
// 值钱的东西来了，必须加上这一行，包括代码设置代码也是同理
<uses-permission android:name="com.android.alarm.permission.SET_ALARM"/>