8.4.2 Fresco

Fresco是Facebook公司的黑科技：http://fresco-cn.org/

　　真三级缓存，变换后的BItmap(内存)，变换前的原始图片(内存)，硬盘缓存。在内存管理上做到了极致。对于重度图片使用的APP应该是非常好的。它一般是直接使用SimpleDraweeView来替换ImageView

　　注意事项：SimpleDraweeView的width和height属性必须是明确值，而不能直接用wrap_content这种内容填充的数值；除非宽度和高度有一个是固定的，然后设置了二者的比例（setAspectRatio），则另一个可以用wrap_content，其实相当于二者都是固定的。正常情况下，一个SimpleDraweeView的各种属性，既可以在布局文件里面设置（如上面的代码）也可以在Java代码里设置，作用是一样的。但当SimpleDraweeView被被一些第三方自定义View包裹的时候，比如一个可下拉刷新的第三方ListView，则此时在布局文件中的一些属性居然是无效的！

　　与ImageLoader 等传统第三方图片处理SDK 不同，Fresco 是基于控件级别的，所以我们把程序中显示网络图片的ImageView 都替换为SimpleDraweeView 。

Fresco 的原理是，设计了一个Image Pipeline 的概念，它负责先后检查内存、磁盘文件（Disk），如果都没有再从网络下载图片。我们可以像配置ImageLoader 那样配置Fresco 中的Image Pipeline，使用ImagePipelineConfig来做这个事情。
　　Fresco 有3 个线程池，其中3 个线程用于网络下载图片，2 个线程用于磁盘文件的读写，还有2 个线程用于CPU 相关操作，比如图片解码、转换，以及放在后台执行的一些费时操作。
　　接下来介绍Fresco 三层缓存的概念。这才是Fresco 最核心的技术，它比其他图片SDK吃内存小，就在于这个全新的缓存设计。

• 第一层：Bitmap 缓存：在Android 5.0 系统中，考虑到内存管理有了很大改进，所以Bitmap 缓存位于Java 的堆（heap）中。 ‰而在Android 4.x 和更低的系统，Bitmap 缓存位于ashmem（匿名共享内存） 中，而不是位于Java 的堆（heap）中。这意味着图片的创建和回收不会引发过多的GC，从而让App 运行得更快。当App 切换到后台时，Bitmap 缓存会被清空。
• 第二层：内存缓存：内存缓存中存储了图片的原始压缩格式。从内存缓存中取出的图片，在显示前必须先解码。当App 切换到后台时，内存缓存也会被清空。
• 第三层：磁盘缓存：磁盘缓存，又名本地存储。磁盘缓存中存储的也是图片的原始压缩格式。在使用前也要先解码。当App 切换到后台时，磁盘缓存不会丢失，即使关机也不会。

Fresco 有很多高级的应用，对于大部分App 而言，基本还用不到。

Image pipeline 负责完成加载图像，变成Android设备可呈现的形式所要经历的大致流程如下: 

• a、根据Uri在已解码的（Bitmap缓存）内存缓存中查找，找到了则返回Bitmap对象；
• b、如果没找到，则开启后台线程开始后续的工作。
• c、根据Uri在未解码的内存缓存中查找，若找到了则解码，然后缓存到已解码的内存缓存中，并且返回Bitmap对象。
• d、如果在未解码的内存缓存中没找到，则根据Uri在磁盘缓存中查找，若找到了则读取数据（byte数组），并缓存到未解码的内存缓存中，解码、然后缓存到已解码的内存缓存中，并且返回Bitmap对象。
• e、如果在磁盘缓存中没找到，则从网络或者本地加载数据。加载完成后，依次缓存到磁盘缓存、未解码的内存缓存中。解码、然后缓存到已解码的内存缓存中，并且返回Bitmap对象。

Drawees 

　　Fresco 中设计有一个叫做 Drawees 模块，负责图片的呈现。它由三个元素组成分别是： 
　　　　　　DraweeView 继承于 View, 负责图片的显示。 
　　　　　　DraweeHierarchy 用于组织和维护最终绘制和呈现的 Drawable 对象。 
　　　　　　DraweeController 负责和ImagePipeline的交互，可以创建一个这个类的实例，来实现对所要显示的图片做更多的控制。 
　　一般情况下，使用 SimpleDraweeView 即可，你可以配置其XML属性来实现各式各样的展示效果。

a、在图片加载完成前显示占位图； 
b、在图片加载的过程中显示加载进度图； 
c、加载成功后，将占位图或者加载进度图，自动替换为目标图片。 
d、加载失败后，它会显示加载失败的图（若没配置加载失败的图，则显示的是占位图） 
e、加载失败后，若配置过重试图，则会显示重试图，用户点击可以重新去加载图片（默认配置可重试3次） 
f、自定义居中焦点（配合Google提供的服务可以实现人脸识别，经测试国内目前使用不了） 
g、显示圆角图、圆形图和圆圈； 
h、添加覆盖物（图层叠加）； 
j、 实现图片的按下效果； 
k、图片的渐进式呈现；（目前只支持Jpeg格式的图片） 
x、当图片不再显示在屏幕上时，它会及时地释放内存和空间占用。

Fresco目前所支持的图片格式 
　　　　静态图：png、jpg、web 　　　　动态图：gif、web格式的gif

---

DEMO：Fresco + RecyclerView三种样式加载本机图片

       

1、在build.gradle文件中添加依赖

dependencies {
    // ......

    compile 'com.facebook.fresco:fresco:0.14.1'
    compile 'com.facebook.fresco:animated-base-support:0.14.1'  // 在 API < 14 上的机器支持 WebP 时
    compile 'com.facebook.fresco:animated-gif:0.14.1'　　　　　　 // 支持GIF动图
    compile 'com.facebook.fresco:webpsupport:0.14.1'　　　　　　　// 支持WebP
    compile 'com.facebook.fresco:animated-webp:0.14.1'　　　　　　// 支持WebP动图
    compile 'com.facebook.fresco:imagepipeline-okhttp3:0.14.1'　// 网络实现层想使用okhttp3
}

 2. 初始化Fresco

public class MyApplication extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        Fresco.initialize(this);
    }
}

3. XML文件

1) activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.xmic.view.recycleviewdemo.MainActivity">
    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyview"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </android.support.v7.widget.RecyclerView>
</RelativeLayout>

2)  item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:fresco="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:padding="5dp"
    app:placeholderImage="@mipmap/ic_launcher">
    <com.facebook.drawee.view.SimpleDraweeView
        android:id="@+id/sdv_img"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        fresco:fadeDuration="300"
        fresco:actualImageScaleType="focusCrop"
        fresco:retryImage="@drawable/retry"
        fresco:retryImageScaleType="centerCrop"
        fresco:progressBarImage="@drawable/retry"
        fresco:progressBarImageScaleType="centerInside"
        fresco:progressBarAutoRotateInterval="500"
        fresco:failureImage="@drawable/fault"
        fresco:failureImageScaleType="fitCenter" />
    <TextView
        android:id="@+id/tv_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal|bottom"
        android:layout_gravity="center"
        android:layout_below="@+id/sdv_img"
        android:layout_alignParentBottom="true"
        android:background="#cccccc"
        android:text="Image Titel"/>
</RelativeLayout>

3) item_list.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:fresco="http://schemas.android.com/apk/res-auto"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="50dp">
    <com.facebook.drawee.view.SimpleDraweeView
        android:id="@+id/sdv_img"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_gravity="center"
        android:background="#aaaaaa"
        android:layout_marginLeft="10dp"
        android:layout_centerVertical="true"
        app:placeholderImage="@mipmap/ic_launcher"
        fresco:failureImage="@drawable/fault"
        fresco:failureImageScaleType="center"
        fresco:roundAsCircle="true"
        fresco:roundedCornerRadius="180dp"
        fresco:actualImageScaleType="focusCrop" />
    <TextView
        android:id="@+id/tv_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="20dp"
        android:layout_gravity="center"
        android:text="Image Titel"/>
</LinearLayout>

4. Java文件

1) 主界面 MainActivity.java

package com.xmic.view.recycleviewdemo;

import android.app.ProgressDialog;
import android.content.ContentResolver;
import android.content.Context;
import android.database.Cursor;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.RelativeLayout;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class MainActivity extends AppCompatActivity implements  RvAdpter.OnItemClickListener{
    private final String TAG = MainActivity.class.getSimpleName();
    private final static int SCAN_OK = 1;
    private final static int TYPE_WATERFALL = 0;
    private final static int TYPE_LISTVIEW = 1;
    private final static int TYPE_GRIDVIEW = 2;
    private RecyclerView mRecyclerView;
    private RvAdpter mAdpter;
    private ProgressDialog mProgressDialog;
    private List<Product> imageList = new ArrayList<Product>();
    RecyclerView.ItemDecoration decorator;

    private Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what){
                case SCAN_OK:
                    showData();
                    break;
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i(TAG,"onCreate()");
        loadData();
        initView();
    }

    private void initView(){
        mRecyclerView = (RecyclerView) findViewById(R.id.recyview);
    }

    private void loadData(){
        mProgressDialog = ProgressDialog.show(this,null,"Loading...");
        new Thread(new Runnable() {
            @Override
            public void run() {
                ArrayList<HashMap<String,String>> pics = getAllPictures(getApplicationContext());
                BitmapFactory.Options options = new BitmapFactory.Options();
                options.inJustDecodeBounds = true;
                if(pics != null)
                    for(int i=0; i< pics.size();i++){
                        Product item = new Product();
                        item.setId(pics.get(i).get("image_id"));
                        item.setLocalThumbPosition(pics.get(i).get("thumbnail_path"));
                        item.setProductName(pics.get(i).get("image_name"));
                        item.setLocalPosition(pics.get(i).get("image_path"));
                        BitmapFactory.decodeFile(item.getLocalPosition(), options);
                        item.setWidth(options.outWidth);
                        item.setHeight(options.outHeight);
                        item.setRatio((float)item.getWidth()/(float)item.getHeight());
                        imageList.add(item);
                    }
                mHandler.sendEmptyMessage(SCAN_OK);
            }
        }).start();
    }

    public static ArrayList<HashMap<String,String>> getAllPictures(Context context) {
        ArrayList<HashMap<String,String>> picturemaps = new ArrayList<>();
        HashMap<String,String> picturemap;
        ContentResolver cr = context.getContentResolver();
        //先得到缩略图的URL和对应的图片id
        Cursor cursor = cr.query(
                MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI,
                new String[]{
                        MediaStore.Images.Thumbnails.IMAGE_ID,
                        MediaStore.Images.Thumbnails.DATA
                },
                null,
                null,
                null);
        if (cursor.moveToFirst()) {
            do {
                picturemap = new HashMap<>();
                picturemap.put("image_id",cursor.getInt(0)+"");
                picturemap.put("thumbnail_path",cursor.getString(1));
                picturemaps.add(picturemap);
            } while (cursor.moveToNext());
            cursor.close();
        }
        //再得到正常图片的path
        for (int i = 0;i<picturemaps.size();i++) {
            picturemap = picturemaps.get(i);
            String media_id = picturemap.get("image_id");
            cursor = cr.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
                    new String[]{
                            MediaStore.Images.Media.DATA,
                            MediaStore.Images.Media.DISPLAY_NAME
                    },
                    MediaStore.Audio.Media._ID + "=" + media_id,
                    null,
                    null
            );
            if (cursor.moveToFirst()) {
                do {
                    picturemap.put("image_path",cursor.getString(0));
                    picturemap.put("image_name",cursor.getString(1));
                    picturemaps.set(i,picturemap);
                } while (cursor.moveToNext());
                cursor.close();
            }
        }
        return picturemaps;
    }

    private void showData(){
        Log.i(TAG,"showData()");
        mProgressDialog.dismiss();
        mAdpter = new RvAdpter(MainActivity.this,imageList);
        mAdpter.setOnItemClickListener(this);
        showViewStyle(TYPE_WATERFALL);
    }

    private void showViewStyle(int type){
        /**
         *  用来确定每一个item如何进行排列摆放
         *  StaggeredGridLayoutManager  瀑布流
         *  LinearLayoutManager         相当于ListView的效果
         *  GridLayoutManager           相当于GridView的效果
         */
        mAdpter.setType(type);
        switch (type){
            case TYPE_WATERFALL: //瀑布流
                mRecyclerView.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,RelativeLayout.LayoutParams.MATCH_PARENT));
                mRecyclerView.removeItemDecoration(decorator);
                mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL));
                decorator = new DividerGridItemDecoration(this);
                mRecyclerView.addItemDecoration(decorator);
                break;
            case TYPE_LISTVIEW: // ListView
                mRecyclerView.removeItemDecoration(decorator);
                mRecyclerView.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,RelativeLayout.LayoutParams.MATCH_PARENT));
                mRecyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false));
                decorator = new DividerItemDecoration(this,DividerItemDecoration.VERTICAL_LIST);
                mRecyclerView.addItemDecoration(decorator);
                break;
            case TYPE_GRIDVIEW: // GridView
                mRecyclerView.removeItemDecoration(decorator);
                mRecyclerView.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,RelativeLayout.LayoutParams.MATCH_PARENT));
                mRecyclerView.setLayoutManager(new GridLayoutManager(this, 3));
                decorator = new DividerGridItemDecoration(this);
                mRecyclerView.addItemDecoration(decorator);
                break;
        }
        mRecyclerView.setAdapter(mAdpter);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        switch (id){
            case R.id.menu_add:
                mAdpter.addItem();
                break;
            case R.id.menu_waterfall:
                showViewStyle(0);
                break;
            case R.id.menu_listview:
                showViewStyle(1);
                break;
            case R.id.menu_gridview:
                showViewStyle(2);
                break;
        }
        mAdpter.notifyDataSetChanged();
        return true;
    }

    @Override
    public void onItemClick(int position, Product data) {
        Log.e(TAG, "onItemClick: " + position );
        Toast.makeText(MainActivity.this,"Click: "+data.getProductName(),Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onItemLonkClick(int position) {
        Log.e(TAG, "onItemLonkClick: " + position );
        Toast.makeText(MainActivity.this,"Remove Item: " + position,Toast.LENGTH_SHORT).show();
        mAdpter.removeItem(position);
    }
}

2) 适配器 RvAdapter.java

package com.xmic.view.recycleviewdemo;

import android.content.Context;
import android.net.Uri;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import com.facebook.drawee.backends.pipeline.Fresco;
import com.facebook.drawee.drawable.ScalingUtils;
import com.facebook.drawee.interfaces.DraweeController;
import com.facebook.drawee.view.SimpleDraweeView;
import com.facebook.imagepipeline.request.ImageRequest;

import java.util.List;

import static com.xmic.view.recycleviewdemo.R.layout.item;
import static com.xmic.view.recycleviewdemo.R.layout.item_list;

/**
 * Created by neek.chen on 2016/11/15.
 */

public class RvAdpter extends RecyclerView.Adapter<RvAdpter.MyViewHolder> implements View.OnClickListener,View.OnLongClickListener{
    private Context context;
    private RecyclerView mRecyclerView;//用来计算Child位置
    private int type = 0;
    private List<Product> list;
    private OnItemClickListener onItemClickListener;

    public interface OnItemClickListener{
        void onItemClick(int position, Product data);
        void onItemLonkClick(int position);
    }

    public RvAdpter(Context context, List<Product> list){
        this.context = context;
        this.list = list;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View contentView;
        if(type == 1)
            contentView = LayoutInflater.from(context).inflate(item_list,parent,false);
        else
            contentView = LayoutInflater.from(context).inflate(item,parent,false);
        contentView.setOnClickListener(this);
        contentView.setOnLongClickListener(this);
        return new MyViewHolder(contentView);
    }

    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        mRecyclerView = recyclerView;
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, final int position) {
        if(list == null)
            return;
        final Product item = list.get(position);
        if(type == 1)
            holder.title.setText(item.getProductName());
        else if(type == 0) {
//            holder.itemView
            holder.title.setVisibility(View.GONE);
        }
        else
            holder.title.setText(position + "");
        String filePath = "file://" + Uri.parse(item.getLocalPosition());
        String fileThumbPath = "file://" + Uri.parse(item.getLocalThumbPosition());
        DraweeController control = Fresco.newDraweeControllerBuilder()
                                        .setLowResImageRequest(ImageRequest.fromUri(fileThumbPath))
//                                      .setImageRequest(ImageRequest.fromUri(filePath))
                                        .setAutoPlayAnimations(true)
                                        .setOldController( holder.img.getController())
                                        .build();
        holder.img.setController(control);
        holder.img.setAspectRatio(item.getRatio());
    }

    @Override
    public int getItemCount() {
        return list == null ? 0 : list.size();
    }

    @Override
    public void onClick(View v) {
        int childAdapterPosition = mRecyclerView.getChildAdapterPosition(v);
        if (childAdapterPosition>= 0 && onItemClickListener!= null)
            onItemClickListener.onItemClick(childAdapterPosition,list.get(childAdapterPosition));
    }

    @Override
    public boolean onLongClick(View v) {
        int childAdapterPosition = mRecyclerView.getChildAdapterPosition(v);
        if (onItemClickListener!= null)
            onItemClickListener.onItemLonkClick(childAdapterPosition);
        return false;
    }

    public void setOnItemClickListener(OnItemClickListener onItemClickListener){
        this.onItemClickListener = onItemClickListener;
    }

    public void setType(int type){
        this.type = type;
    }

    public class MyViewHolder extends RecyclerView.ViewHolder{
        private SimpleDraweeView img;
        public TextView title;
        public MyViewHolder(View item){
            super(item);
            img = (SimpleDraweeView)item.findViewById(R.id.sdv_img);
            img.getHierarchy().setActualImageScaleType(ScalingUtils.ScaleType.FIT_XY);
            title = (TextView)item.findViewById(R.id.tv_title);
        }
    }

    public void addItem(){
    }

    public void removeItem(final int positon){
        list.remove(positon);
        notifyItemRemoved(positon);
    }

}

3) 分隔线

　　采用通用的 DividerGridItemDecoration和 DividerItemDecoration

4) 图片对象Product

　　 private String id;
    private String localPosition;
    private String localThumbPosition;
    private String productName;
    private int width;
    private int height;
    private float ratio;

Fresco的各种使用场景

 引用：Android图片加载神器之Fresco，基于各种使用场景的讲解

从网络加载一张图片

String url = "http://xxx.jpg";
ImageLoader.loadImage((SimpleDraweeView)findViewById(R.id.sdv_1), url);

 1. 显示一张图片

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_1"
            android:layout_width="90dp"
            android:layout_height="90dp"
            app:actualImageScaleType="centerCrop"/>

2. 显示一张圆形图片

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_2"
            android:layout_width="90dp"
            android:layout_height="90dp"
            android:layout_marginTop="15dp"
            app:actualImageScaleType="centerCrop"
            app:roundAsCircle="true"/>

 3. 显示一张圆形带边框的图片

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_3"
            android:layout_width="90dp"
            android:layout_height="90dp"
            android:layout_marginTop="15dp"
            app:actualImageScaleType="centerCrop"
            app:roundAsCircle="true"
            app:roundingBorderColor="#fff3cf44"
            app:roundingBorderWidth="2dp"/>

4. 显示一张圆角图片

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_4"
            android:layout_width="90dp"
            android:layout_height="90dp"
            android:layout_marginTop="15dp"
            app:actualImageScaleType="centerCrop"
            app:roundAsCircle="false"
            app:roundedCornerRadius="10dp"/>

 5. 显示一张底部是圆角的图片

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_5"
            android:layout_width="90dp"
            android:layout_height="90dp"
            android:layout_marginTop="15dp"
            app:actualImageScaleType="centerCrop"
            app:roundAsCircle="false"
            app:roundedCornerRadius="10dp"
            app:roundTopLeft="false"
            app:roundTopRight="false"
            app:roundBottomLeft="true"
            app:roundBottomRight="true"/>

6. 显示一张左上和右下是圆角的图片

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_6"
            android:layout_width="90dp"
            android:layout_height="90dp"
            android:layout_marginTop="15dp"
            app:actualImageScaleType="centerCrop"
            app:roundAsCircle="false"
            app:roundedCornerRadius="10dp"
            app:roundTopLeft="true"
            app:roundTopRight="false"
            app:roundBottomLeft="false"
            app:roundBottomRight="true"/>

7. 设置占位图

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_7"
            android:layout_width="90dp"
            android:layout_height="90dp"
            android:layout_marginTop="15dp"
            app:actualImageScaleType="centerCrop"
            app:placeholderImage="@mipmap/ic_launcher"
            app:placeholderImageScaleType="centerCrop" />

8. 带动画的显示（从半透明到不透明）

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_8"
            android:layout_width="90dp"
            android:layout_height="90dp"
            android:layout_marginTop="15dp"
            app:actualImageScaleType="centerCrop"
            app:fadeDuration=""/>

9. 图层叠加显示

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_10"
            android:layout_width="90dp"
            android:layout_height="90dp"
            android:layout_marginTop="15dp"
            app:actualImageScaleType="centerCrop"
            app:overlayImage="@mipmap/ic_launcher"/>

10. 其它的属性的配置，比如加载进度、加载失败、重试图

<com.facebook.drawee.view.SimpleDraweeView
            android:id="@+id/sdv_11"
            android:layout_width="90dp"
            android:layout_height="90dp"
            android:layout_marginTop="15dp"
            app:actualImageScaleType="centerCrop"
            app:failureImage="@mipmap/ic_launcher"
            app:failureImageScaleType="centerInside"
            app:retryImage="@mipmap/ic_launcher"
            app:retryImageScaleType="centerCrop"
            app:progressBarImage="@mipmap/ic_launcher"
            app:progressBarImageScaleType="centerCrop"
            app:progressBarAutoRotateInterval=""/>

 11. 从本地文件（比如SDCard上）加载图片

public static void loadFile(final SimpleDraweeView draweeView, String filePath, final int reqWidth, final int reqHeight) {
        Uri uri = new Uri.Builder()
                .scheme(UriUtil.LOCAL_FILE_SCHEME)
                .path(filePath)
                .build();
        ImageRequest request = ImageRequestBuilder.newBuilderWithSource(uri)
                .setRotationOptions(RotationOptions.autoRotate())
                .setLocalThumbnailPreviewsEnabled(true)
                .setResizeOptions(new ResizeOptions(reqWidth, reqHeight))
                .build();
        DraweeController controller = Fresco.newDraweeControllerBuilder()
                .setImageRequest(request)
                .setOldController(draweeView.getController())
                .setControllerListener(new BaseControllerListener<ImageInfo>() {
                    @Override
                    public void onFinalImageSet(String id, @Nullable ImageInfo imageInfo, @Nullable Animatable anim) {
                        if (imageInfo == null) {
                            return;
                        }

                        ViewGroup.LayoutParams vp = draweeView.getLayoutParams();
                        vp.width = reqWidth;
                        vp.height = reqHeight;
                        draweeView.requestLayout();
                    }
                })
                .build();
        draweeView.setController(controller);
    }

调用：

ImageLoader.loadFile((SimpleDraweeView)itemView, photoInfo.thumbnailUrl, , );

 12. 从本地资源（Resources）加载图片

public static void loadDrawable(SimpleDraweeView draweeView, int resId) {
        Uri uri = new Uri.Builder()
                .scheme(UriUtil.LOCAL_RESOURCE_SCHEME)
                .path(String.valueOf(resId))
                .build();
        DraweeController controller = Fresco.newDraweeControllerBuilder()
                .setUri(uri)
                .setOldController(draweeView.getController())
                .build();
        draweeView.setController(controller);
    }

13. 对图片进行性高斯模糊处理

public static void loadImageBlur(final SimpleDraweeView draweeView, String url) {
        loadImage(draweeView, url, new BasePostprocessor() {
            @Override
            public String getName() {
                return "blurPostprocessor";
            }

            @Override
            public void process(Bitmap bitmap) {
                BitmapBlurHelper.blur(bitmap, 35);
            }
        });
    }

其内部调用的方法

public static void loadImage(SimpleDraweeView simpleDraweeView, String url, BasePostprocessor processor) {
        if (TextUtils.isEmpty(url)) {
            return;
        }

        Uri uri = Uri.parse(url);
        ImageRequest request = ImageRequestBuilder.newBuilderWithSource(uri)
                .setRotationOptions(RotationOptions.autoRotate())
                .setPostprocessor(processor)
                .build();
        DraweeController controller = Fresco.newDraweeControllerBuilder()
                .setImageRequest(request)
                .setOldController(simpleDraweeView.getController())
                .build();
        simpleDraweeView.setController(controller);
    }

调用：

String url = "http://xxx.jpg";
  SimpleDraweeView simpleDraweeView = (SimpleDraweeView)findViewById(R.id.sdv_1);
  simpleDraweeView.setAspectRatio(0.7f);
  ViewGroup.LayoutParams lvp = simpleDraweeView.getLayoutParams();
  lvp.width = DensityUtil.getDisplayWidth(this);
  ImageLoader.loadImageBlur(simpleDraweeView, url,
                DensityUtil.getDisplayWidth(this), DensityUtil.getDisplayHeight(this));

 14. 未知宽高比的情况下显示图片

String url = "http://xx.jpg";
SimpleDraweeView simpleDraweeView = (SimpleDraweeView)findViewById(R.id.sdv_1);
ImageLoader.loadImage(simpleDraweeView, url, new SingleImageControllerListener(simpleDraweeView));

 15. 从网络加载并显示gif格式的图片

 String url = "http://xxx.gif";
   SimpleDraweeView simpleDraweeView = (SimpleDraweeView)findViewById(R.id.sdv);
   ImageLoader.loadImage(simpleDraweeView, url);

 16. 加载并显示webp格式的图片

SimpleDraweeView simpleDraweeView = (SimpleDraweeView)findViewById(R.id.sdv_1);
        ViewGroup.LayoutParams lvp = simpleDraweeView.getLayoutParams();
        lvp.width = DensityUtil.getDisplayWidth(this);
        simpleDraweeView.setAspectRatio(0.6f); // 设置宽高比

        ImageLoader.loadDrawable(simpleDraweeView, R.drawable.meizi_webp,
                DensityUtil.getDisplayWidth(this), DensityUtil.getDisplayHeight(this));

17. 从内存缓存中移除指定图片的缓存

　　　　　　if (!TextUtils.isEmpty(photoInfo.originalUrl)) {
                ImagePipeline imagePipeline = Fresco.getImagePipeline();
                Uri uri = Uri.parse(photoInfo.originalUrl);
                if (imagePipeline.isInBitmapMemoryCache(uri)) {
                    imagePipeline.evictFromMemoryCache(uri);
                }
            }

 18. 从磁盘缓存中移除指定图片的缓存

　　　　ImagePipeline imagePipeline = Fresco.getImagePipeline();
        Uri uri = Uri.parse(photoInfo.originalUrl);
        // 下面的操作是异步的
        if (imagePipeline.isInDiskCacheSync(uri)) {
            imagePipeline.evictFromDiskCache(uri);
        }

 19、清空磁盘缓存

Fresco.getImagePipeline().clearDiskCaches();

20、清空内存缓存

Fresco.getImagePipeline().clearMemoryCaches();

 21、清空缓存（内存缓存 + 磁盘缓存）

Fresco.getImagePipeline().clearCaches();

 22、在列表视图滚动时，不加载图片，等滚动停止后再开始加载图片，提升列表视图的滚动流畅度。

 // 需要暂停网络请求时调用
    public static void pause(){
        Fresco.getImagePipeline().pause();
    }
    // 需要恢复网络请求时调用
    public static void resume(){
        Fresco.getImagePipeline().resume();
    }

23、下载图片存储到指定的路径

/**
     * 从网络下载图片
     * 1、根据提供的图片URL，获取图片数据流
     * 2、将得到的数据流写入指定路径的本地文件
     *
     * @param url            URL
     * @param loadFileResult LoadFileResult
     */
    public static void downloadImage(Context context, String url, final DownloadImageResult loadFileResult) {
        if (TextUtils.isEmpty(url)) {
            return;
        }

        Uri uri = Uri.parse(url);
        ImagePipeline imagePipeline = Fresco.getImagePipeline();
        ImageRequestBuilder builder = ImageRequestBuilder.newBuilderWithSource(uri);
        ImageRequest imageRequest = builder.build();

        // 获取未解码的图片数据
        DataSource<CloseableReference<PooledByteBuffer>> dataSource = imagePipeline.fetchEncodedImage(imageRequest, context);
        dataSource.subscribe(new BaseDataSubscriber<CloseableReference<PooledByteBuffer>>() {
            @Override
            public void onNewResultImpl(DataSource<CloseableReference<PooledByteBuffer>> dataSource) {
                if (!dataSource.isFinished() || loadFileResult == null) {
                    return;
                }

                CloseableReference<PooledByteBuffer> imageReference = dataSource.getResult();
                if (imageReference != null) {
                    final CloseableReference<PooledByteBuffer> closeableReference = imageReference.clone();
                    try {
                        PooledByteBuffer pooledByteBuffer = closeableReference.get();
                        InputStream inputStream = new PooledByteBufferInputStream(pooledByteBuffer);
                        String photoPath = loadFileResult.getFilePath();
                        Log.i("ImageLoader", "photoPath = " + photoPath);

                        byte[] data = StreamTool.read(inputStream);
                        StreamTool.write(photoPath, data);
                        loadFileResult.onResult(photoPath);
                    } catch (IOException e) {
                        loadFileResult.onFail();
                        e.printStackTrace();
                    } finally {
                        imageReference.close();
                        closeableReference.close();
                    }
                }
            }

            @Override
            public void onFailureImpl(DataSource dataSource) {
                if (loadFileResult != null) {
                    loadFileResult.onFail();
                }

                Throwable throwable = dataSource.getFailureCause();
                if (throwable != null) {
                    Log.e("ImageLoader", "onFailureImpl = " + throwable.toString());
                }
            }
        }, Executors.newSingleThreadExecutor());
    }

调用

String url = "http://xxx.jpg";
    String filePath = "";
    ImageLoader.downloadImage(context, url, new DownloadImageResult(filePath) {

        @Override
        public void onResult(String filePath) {

        }

        @Override
        public void onFail() {

        }
    });

24、不使用SimpleDraweeView组件，但是想使用Fresco去加载图片（两级内存缓存+磁盘缓存要有）并显示到其他组件上（比如显示在TextView的drawableLeft属性上或者显示为View的背景）。

public static void loadTextDrawable(final TextView view, String url, final int direction, final int iconWidth, final int iconHeight) {
        ImageLoader.loadImage(view.getContext(), url, new LoadImageResult() {
            @Override
            public void onResult(Bitmap bitmap) {
                Drawable drawable = new BitmapDrawable(view.getContext().getResources(), bitmap);
                final int width = DensityUtil.dipToPixels(view.getContext(), iconWidth);
                final int height = DensityUtil.dipToPixels(view.getContext(), iconHeight);
                drawable.setBounds(0, 0, width, height);
                switch (direction) {
                    case 0:
                        view.setCompoundDrawables(drawable, null, null, null);
                        break;
                    case 1:
                        view.setCompoundDrawables(null, drawable, null, null);
                        break;
                    case 2:
                        view.setCompoundDrawables(null, null, drawable, null);
                        break;
                    case 3:
                        view.setCompoundDrawables(null, null, null, drawable);
                        break;
                }　　
            }
        });
    }