Glide的使用

Glide是google開發(fā)用于Android加載媒體的類庫滥朱，包括圖片,gif,video,已經(jīng)在很多項(xiàng)目中使用娇斩，靈活快速笆檀。下面我們看如何使用它,如果有什么不對的請不吝指教

• 導(dǎo)入到項(xiàng)目中

    dependencies {
        compile fileTree(include: ['*.jar'], dir: 'libs')
        testCompile 'junit:junit:4.12'
        compile 'com.android.support:appcompat-v7:24.1.1'
        compile 'com.github.bumptech.glide:glide:3.7.0'
        compile 'com.android.support:support-v4:24.1.1'
        }
  

  Glide同樣需要Android Support Library v4武氓，請記得加上support-v4客蹋，不過現(xiàn)在項(xiàng)目基本都包含support-v4遣总。

• 加載圖片

      Glide.with(this).load("http://inthecheesefactory.com/uploads/source/glidepicasso/cover.jpg")
              .asBitmap()
              .into(mImageView);
  

• Glide的生命周期

  

  glide-with

  Glide.with() 不僅僅只是Context還可以是Activity,Fragment等埃脏，傳入后自動適配诗赌，Glide加載圖片是會隨著Activity,Fragment 的生命周期，具體可以參考LifecycleListener晌纫，所以推薦使用Activity,Fragment.

• 設(shè)置圖片大小

  .override(200,200)可以設(shè)置加載圖片大小税迷，但是實(shí)際大小不一定是200x200,通過源碼分析下：

  在BitmapRequestBuilder中默認(rèn)的private Downsampler downsampler = Downsampler.AT_LEAST;

     /**
     * Load and scale the image uniformly (maintaining the image's aspect ratio) so that the smallest edge of the
     * image will be between 1x and 2x the requested size. The larger edge has no maximum size.
     */
    public static final Downsampler AT_LEAST = new Downsampler() {
        @Override
        protected int getSampleSize(int inWidth, int inHeight, int outWidth, int outHeight) {
            return Math.min(inHeight / outHeight, inWidth / outWidth);
        }
  
        @Override
        public String getId() {
            return "AT_LEAST.com.bumptech.glide.load.data.bitmap";
        }
    };
  

  然后在Downsampler中的decode方法中，獲取的Bitmap大小變成1/sampleSize锹漱，倍數(shù)通過getSampleSize計(jì)算所得箭养，

        options.inTempStorage = bytesForOptions;
  
        final int[] inDimens = getDimensions(invalidatingStream, bufferedStream, options);
        final int inWidth = inDimens[0];
        final int inHeight = inDimens[1];
  
        final int degreesToRotate = TransformationUtils.getExifOrientationDegrees(orientation);
        final int sampleSize = getRoundedSampleSize(degreesToRotate, inWidth, inHeight, outWidth, outHeight);
  
        final Bitmap downsampled =
                downsampleWithSize(invalidatingStream, bufferedStream, options, pool, inWidth, inHeight, sampleSize,
                        decodeFormat);
  
        // BitmapFactory swallows exceptions during decodes and in some cases when inBitmap is non null, may catch
        // and log a stack trace but still return a non null bitmap. To avoid displaying partially decoded bitmaps,
        // we catch exceptions reading from the stream in our ExceptionCatchingInputStream and throw them here.
        final Exception streamException = exceptionStream.getException();
        if (streamException != null) {
            throw new RuntimeException(streamException);
        }
  
        Bitmap rotated = null;
        if (downsampled != null) {
            rotated = TransformationUtils.rotateImageExif(downsampled, pool, orientation);
  
            if (!downsampled.equals(rotated) && !pool.put(downsampled)) {
                downsampled.recycle();
            }
        }
  

  inSampleSize 是 BitmapFactory.Options的屬性，應(yīng)該大家都知道哥牍。然后再看看怎么生成.override(200,200)毕泌，如果沒有設(shè)置Glide默認(rèn)是FitCenter，查看FitCenter可以看到圖片截取方式嗅辣。

    public class FitCenter extends BitmapTransformation {
  
        public FitCenter(Context context) {
            super(context);
        }
  
        public FitCenter(BitmapPool bitmapPool) {
            super(bitmapPool);
        }
  
        @Override
        protected Bitmap transform(BitmapPool pool, Bitmap toTransform, int outWidth, int outHeight) {
            return TransformationUtils.fitCenter(toTransform, pool, outWidth, outHeight);
        }
  
        @Override
        public String getId() {
            return "FitCenter.com.bumptech.glide.load.resource.bitmap";
        }
    }
  

  --

     public static Bitmap fitCenter(Bitmap toFit, BitmapPool pool, int width, int height) {
            if (toFit.getWidth() == width && toFit.getHeight() == height) {
                if (Log.isLoggable(TAG, Log.VERBOSE)) {
                    Log.v(TAG, "requested target size matches input, returning input");
                }
                return toFit;
            }
            final float widthPercentage = width / (float) toFit.getWidth();
            final float heightPercentage = height / (float) toFit.getHeight();
            final float minPercentage = Math.min(widthPercentage, heightPercentage);
  
            // take the floor of the target width/height, not round. If the matrix
            // passed into drawBitmap rounds differently, we want to slightly
            // overdraw, not underdraw, to avoid artifacts from bitmap reuse.
            final int targetWidth = (int) (minPercentage * toFit.getWidth());
            final int targetHeight = (int) (minPercentage * toFit.getHeight());
  
            if (toFit.getWidth() == targetWidth && toFit.getHeight() == targetHeight) {
                if (Log.isLoggable(TAG, Log.VERBOSE)) {
                    Log.v(TAG, "adjusted target size matches input, returning input");
                }
                return toFit;
            }
  
            Bitmap.Config config = getSafeConfig(toFit);
            Bitmap toReuse = pool.get(targetWidth, targetHeight, config);
            if (toReuse == null) {
                toReuse = Bitmap.createBitmap(targetWidth, targetHeight, config);
            }
            // We don't add or remove alpha, so keep the alpha setting of the Bitmap we were given.
            TransformationUtils.setAlpha(toFit, toReuse);
  
            if (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, "request: " + width + "x" + height);
                Log.v(TAG, "toFit:   " + toFit.getWidth() + "x" + toFit.getHeight());
                Log.v(TAG, "toReuse: " + toReuse.getWidth() + "x" + toReuse.getHeight());
                Log.v(TAG, "minPct:   " + minPercentage);
            }
  
            Canvas canvas = new Canvas(toReuse);
            Matrix matrix = new Matrix();
            matrix.setScale(minPercentage, minPercentage);
            Paint paint = new Paint(PAINT_FLAGS);
            canvas.drawBitmap(toFit, matrix, paint);
  
            return toReuse;
        }
  

  這里算出圖片的大泻撤骸：

            final float widthPercentage = width / (float) toFit.getWidth();
            final float heightPercentage = height / (float) toFit.getHeight();
            final float minPercentage = Math.min(widthPercentage, heightPercentage);
  

  測試中我們使用的圖片是1080x540,最終生成了200x100.設(shè)置approximate()對應(yīng)Downsampler.AT_LEAST,asIs()對應(yīng)Downsampler.NONE,atMost()對應(yīng)Downsampler.AT_MOST，具體情況可查看Downsampler

• 圖片緩存策略

  測試加載的圖片大小為1080x540澡谭，如果使用了.override(200,200)默認(rèn)緩存一張200x100的圖片,也就是默認(rèn)存儲結(jié)果RESULT愿题，如果想要改變緩存的策略可以這樣設(shè)置：

  .diskCacheStrategy(DiskCacheStrategy.ALL)

  DiskCacheStrategy 分別有以下幾種選擇，ALL緩存原圖和截取后的圖蛙奖，NONE 不緩存潘酗，SOURCE 只緩存原圖，RESULT緩存截取后的圖：

        public enum DiskCacheStrategy {
           /** Caches with both {@link #SOURCE} and {@link #RESULT}. */
           ALL(true, true),
           /** Saves no data to cache. */
           NONE(false, false),
           /** Saves just the original data to cache. */
           SOURCE(true, false),
           /** Saves the media item after all transformations to cache. */
           RESULT(false, true);
  
           private final boolean cacheSource;
           private final boolean cacheResult;
  
           DiskCacheStrategy(boolean cacheSource, boolean cacheResult) {
               this.cacheSource = cacheSource;
               this.cacheResult = cacheResult;
           }
  
           /**
            * Returns true if this request should cache the original unmodified data.
            */
           public boolean cacheSource() {
               return cacheSource;
           }
  
           /**
            * Returns true if this request should cache the final transformed result.
            */
           public boolean cacheResult() {
               return cacheResult;
           }
       }
  

  查看本地緩存如下：

  

  DiskCacheStrategy

  如果圖片需要分享或需要原圖的建議緩存ALL雁仲，否則只緩存RESULT仔夺。

• Glide全局配置

1. 創(chuàng)建GlideModel

    public class GlideConfigModule implements GlideModule {
      @Override
      public void applyOptions(Context context, GlideBuilder builder) {
   
      }
   
      @Override
      public void registerComponents(Context context, Glide glide) {
   
      }
    }
   

2. 在AndroidManifest.xml的meta-data配置GlideModule

    <meta-data android:name="com.branch.www.glidedemo.GlideConfigModule"
               android:value="GlideModule"/>
   

3. 解決GlideModel沖突

   有可能加入的library中也同樣配置了GlideModule,如果配置了多個(gè)會出現(xiàn)沖突，無法編譯運(yùn)行攒砖，解決方式可在AndroidManifest.xml移除

    <meta-data android:name=”com.mypackage.MyGlideModule” tools:node=”remove” />
   

4. 默認(rèn)Bitmap Format 是 RGB_565

   為了降低內(nèi)存消耗缸兔，Glide默認(rèn)配置的Bitmap Format 為 RGB_565日裙，修改GlideBuilder's setDecodeFormat設(shè)置

        builder.setDecodeFormat(DecodeFormat.PREFER_ARGB_8888);
   

5. 配置Disk緩存

   使用GlideBuilder's setDiskCache()方法設(shè)置緩存目錄和大小。
   默認(rèn)Glide使用InternalCacheDiskCacheFactory惰蜜，默認(rèn)最大緩存250M昂拂，這是一個(gè)應(yīng)用內(nèi)部目錄的緩存，緩存的圖片只能本應(yīng)用可以有權(quán)獲取蝎抽。

      builder.setDiskCache(
      new InternalCacheDiskCacheFactory(context, yourSizeInBytes));
   
      builder.setDiskCache(
      new InternalCacheDiskCacheFactory(context, cacheDirectoryName, yourSizeInBytes));
   

   你也可以使用ExternalCacheDiskCacheFactory去設(shè)置SD卡緩存

      builder.setDiskCache(
      new ExternalCacheDiskCacheFactory(context, cacheDirectoryName, yourSizeInBytes));
   

   或者使用DiskLruCacheFactory配置自己管理的緩存目錄和大小

        // If you can figure out the folder without I/O:
        // Calling Context and Environment class methods usually do I/O.
        builder.setDiskCache(
          new DiskLruCacheFactory(getMyCacheLocationWithoutIO(), yourSizeInBytes));
   
        // In case you want to specify a cache folder ("glide"):
        builder.setDiskCache(
          new DiskLruCacheFactory(getMyCacheLocationWithoutIO(), "glide", yourSizeInBytes));
   
        // In case you need to query the file system while determining the folder:
        builder.setDiskCache(new DiskLruCacheFactory(new CacheDirectoryGetter() {
            @Override public File getCacheDirectory() {
                return getMyCacheLocationBlockingIO();
            }
        }), yourSizeInBytes);
   

   或者你想完全控制緩存可以通過實(shí)現(xiàn)DiskCache.Factory然后用DiskLruCacheWrapper去創(chuàng)建你期望的目錄政钟。

        builder.setDiskCache(new DiskCache.Factory() {
        @Override public DiskCache build() {
            File cacheLocation = getMyCacheLocationBlockingIO();
            cacheLocation.mkdirs();
            return DiskLruCacheWrapper.get(cacheLocation, yourSizeInBytes);
         }
        });
   

   如果你不需要任何緩存可以使用DiskCacheAdapter或者自己實(shí)現(xiàn)DiskCache，DiskCacheAdapter內(nèi)部沒有任何實(shí)現(xiàn)樟结。

6. Bitmap Pool

   為了避免Bitmap頻繁解碼，我們通常會在系統(tǒng)內(nèi)存中緩存一部分經(jīng)常使用的圖片精算。GlideBuilder's setBitmapPool()可以設(shè)置你想要的緩存策略瓢宦，緩存大小。例如我們常用的LRU策略灰羽。

        builder.setBitmapPool(new LruBitmapPool(sizeInBytes));
   

   或?qū)崿F(xiàn)BitmapPool自定義一個(gè)吧驮履。

   Glide所有的基本配置都在GlideModule內(nèi)，使用Glide提供的緩存方式如下：

    builder.setDiskCache(new DiskLruCacheFactory(dirPath, DiskCache.Factory.DEFAULT_DISK_CACHE_SIZE));
   

   如果需要自定義實(shí)現(xiàn)DiskCache.Factory廉嚼。

   GlideModule 更多配置如下：

   

   GlideModule

• 自定義加載

  1. SimpleTarget

     如果單純的想獲得Bitmap玫镐，顯不顯示或者其他再定，則可以使用SimpleTarget

       Glide.with(this).load("http://inthecheesefactory.com/uploads/source/glidepicasso/cover.jpg")
            .asBitmap()
            .diskCacheStrategy(DiskCacheStrategy.ALL)
            .into(new SimpleTarget<Bitmap>() {
              @Override
              public void onResourceReady(Bitmap resource, GlideAnimation<? super Bitmap> glideAnimation) {
     
              }
            });
     

     需要注意的是如果你想獲取Bitmap那么一定不想因?yàn)?code>Activity,Fragment的生命周期影響怠噪，因此Glide.with(context)使用Context,同時(shí)為了避免內(nèi)存泄露建議SimpleTarget使用靜態(tài)內(nèi)部類而不是內(nèi)部類（靜態(tài)內(nèi)部類不持有外部引用）恐似。

  2. ViewTarget

     如果想要在圖片加載完成后設(shè)置一些動畫則可以使用ViewTarget

           Glide.with(this).load("http://inthecheesefactory.com/uploads/source/glidepicasso/cover.jpg")
                .asBitmap()
                .override(500,500)
                .diskCacheStrategy(DiskCacheStrategy.ALL)
                .into(new ViewTarget<ImageView, Bitmap>(mImageView) {
                  @Override
                  public void onResourceReady(Bitmap resource, GlideAnimation<? super Bitmap> glideAnimation) {
     
                    this.view.setImageBitmap(resource);
                  }
                });
     

     如果.asGif()使用GlideDrawable替換Bitmap，同時(shí)ViewTarget中包含onStart(), onStop(), onDestroy()生命周期回調(diào)傍念。

     如果想要繼續(xù)保留默認(rèn)的特性可以相應(yīng)的使用GlideDrawableImageViewTarget在asGif()之后矫夷，使用BitmapImageViewTarget在asBitmap()之后。

• 自定義url

  通過width x height拼接url下載指定大小的圖片憋槐，或者根據(jù)屏幕大小選擇高双藕，中，低三種分別率的圖片url阳仔。

  使用http或https加載圖片可以繼承BaseGlideUrlLoader

        public interface MyDataModel {
        public String buildUrl(int width, int height);
        } 
  
        public class MyUrlLoader extends BaseGlideUrlLoader<MyDataModel> {
        @Override
        protected String getUrl(MyDataModel model, int width, int height) {
            // Construct the url for the correct size here.
            return model.buildUrl(width, height);
        }
        }
  

  MyDataModel就相當(dāng)于我們的媒體model,里面有當(dāng)前媒體的類型(image/gif/video)忧陪，url等屬性。

  然后你可以在加載是這樣使用：

         Glide.with(yourFragment)
        .using(new MyUrlLoader())
        .load(yourModel)
        .into(yourView);
  

  如果不想每次都使用.using(new MyUrlLoader())近范，可以在前面我們的GlideModule中配置

        public class MyGlideModule implements GlideModule {
        ...
        @Override
        public void registerComponents(Context context, Glide glide) {
            glide.register(MyDataModel.class, InputStream.class, 
                new MyUrlLoader.Factory());
        }
        }
  

  配置后加載時(shí)跳過.using()

• <span id="getBitmap">在后臺線程下載</span>

  1. downloadOnly

     downloadOnly有異步版和同步版嘶摊，如果已經(jīng)在后臺線程中執(zhí)行必須同步版

          FutureTarget<File> future = Glide.with(applicationContext)
          .load(yourUrl)
          .downloadOnly(500, 500);
          File cacheFile = future.get();
     

     這種方式在主線程中會阻塞主線程。如果想要在主線程中執(zhí)行可以使用前面講到的SimpleTarget

          Glide.with(this)
            .load("http://inthecheesefactory.com/uploads/source/glidepicasso/cover.jpg")
            .downloadOnly(new SimpleTarget<File>() {
              @Override
              public void onResourceReady(File resource, GlideAnimation<? super File> glideAnimation) {
     
              }
            });
     

  2. into

     使用into可以用于下載顺又，下面是在后臺線程中的使用：

          Bitmap myBitmap = Glide.with(applicationContext)
          .load(yourUrl)
          .asBitmap()
          .centerCrop()
          .into(500, 500)
          .get()
     

     如果想在主線程中使用同樣可以使用SimpleTarget

• 清除緩存

    Glide.get(getApplicationContext()).clearMemory();
    Glide.get(getApplicationContext()).clearDiskCache();
  

• 怎么使緩存失效

  有時(shí)我們并不是想要清理所有緩存更卒，只是app版本變動則原來的緩存可能不需要了，或本地圖片庫中圖片變更但是文件名地址沒有變則可能就出現(xiàn)繼續(xù)使用原來的縮略圖或.override(200,200)使用的小圖稚照，其實(shí)最好的情況是如果數(shù)據(jù)變更則相應(yīng)的改變url蹂空，如果不改變可以使用StringSignature解決這個(gè)問題.

  1. 通過版本使緩存失效

      Glide.with(yourFragment)
          .load(yourFileDataModel)
          .signature(new StringSignature(yourVersionMetadata))
          .into(yourImageView);
     

  2. MediaStore中的數(shù)據(jù)

      Glide.with(fragment)
          .load(mediaStoreUri)
          .signature(new MediaStoreSignature(mimeType, dateModified, orientation))
          .into(view);
     

  3. 自定義

     實(shí)現(xiàn)Key接口俯萌，重寫equals(), hashCode() 和 updateDiskCacheKey() 方法，可以參考StringSignature或MediaStoreSignature的實(shí)現(xiàn)上枕。

• Transformations

  1. 默認(rèn)的Transformations

     Fit center

     相當(dāng)于Android's ScaleType.FIT_CENTER.

          Glide.with(yourFragment)
          .load(yourUrl)
          .fitCenter()
          .into(yourView);
     

     Center crop

     相當(dāng)于Android's ScaleType.CENTER_CROP

          Glide.with(yourFragment)
          .load(yourUrl)
          .centerCrop()
          .into(yourView);
     

  2. 自定義transformations

     最簡單的方式是集成BitmapTransformation

          private static class MyTransformation extends BitmapTransformation {
     
          public MyTransformation(Context context) {
             super(context);
          }
     
          @Override
          protected Bitmap transform(BitmapPool pool, Bitmap toTransform, 
                  int outWidth, int outHeight) {
             Bitmap myTransformedBitmap = ... // apply some transformation here.
             return myTransformedBitmap;
          }
     
          @Override
          public String getId() {
              // Return some id that uniquely identifies your transformation.
              return "com.example.myapp.MyTransformation";
          }
          }
     

     然后使用

     .transform(new MyTransformation(context))

     Transformations 有各種豐富的效果咐熙。

     BitmapTransformation可以用于改變bitmap形狀，顏色辨萍，截取棋恼，放大，所有等操作锈玉。

• 設(shè)置占位圖和加載錯(cuò)誤圖

    .placeholder(R.drawable.placeholder)
    .error(R.drawable.imagenotfound)
  

• ProGuard

    -keep public class * implements com.bumptech.glide.module.GlideModule
    -keep public enum com.bumptech.glide.load.resource.bitmap.ImageHeaderParser$** {
      **[] $VALUES;
      public *;
    }
    -keepresourcexmlelements manifest/application/meta-data@value=GlideModule
  

• 相關(guān)問題問答

  1. 通過url獲取已經(jīng)下載的圖片

     使用downloadOnly或into

  2. 是否支持Webp

     Android 4.0 以上能支持

  3. 在AndroidManifest.xml的meta-data配置GlideModule是如何獲取的

     查看源碼在Glide.get(Context)

           public static Glide get(Context context) {
          if (glide == null) {
            synchronized (Glide.class) {
              if (glide == null) {
                Context applicationContext = context.getApplicationContext();
                List<GlideModule> modules = new ManifestParser(applicationContext).parse();
     
                GlideBuilder builder = new GlideBuilder(applicationContext);
                for (GlideModule module : modules) {
                  module.applyOptions(applicationContext, builder);
                }
                glide = builder.createGlide();
                for (GlideModule module : modules) {
                  module.registerComponents(applicationContext, glide.registry);
                }
              }
            }
          }
     
          return glide;
        }
     

     可以看到GlideModule的獲取在ManifestParser同時(shí)也發(fā)現(xiàn)可以設(shè)置多個(gè)爪飘，不過同樣的配置后面的會覆蓋前面的。那么進(jìn)入ManifestParser查看是怎么實(shí)現(xiàn)的拉背。

          public final class ManifestParser {
            private static final String GLIDE_MODULE_VALUE = "GlideModule";
     
            private final Context context;
     
            public ManifestParser(Context context) {
              this.context = context;
            }
     
            public List<GlideModule> parse() {
              List<GlideModule> modules = new ArrayList<>();
              try {
                ApplicationInfo appInfo = context.getPackageManager()
                    .getApplicationInfo(context.getPackageName(), PackageManager.GET_META_DATA);
                if (appInfo.metaData != null) {
                  for (String key : appInfo.metaData.keySet()) {
                    if (GLIDE_MODULE_VALUE.equals(appInfo.metaData.get(key))) {
                      modules.add(parseModule(key));
                    }
                  }
                }
              } catch (PackageManager.NameNotFoundException e) {
                throw new RuntimeException("Unable to find metadata to parse GlideModules", e);
              }
     
              return modules;
            }
     
            private static GlideModule parseModule(String className) {
              Class<?> clazz;
              try {
                clazz = Class.forName(className);
              } catch (ClassNotFoundException e) {
                throw new IllegalArgumentException("Unable to find GlideModule implementation", e);
              }
     
              Object module;
              try {
                module = clazz.newInstance();
              } catch (InstantiationException | IllegalAccessException e) {
                throw new RuntimeException("Unable to instantiate GlideModule implementation for " + clazz,
                    e);
              }
     
              if (!(module instanceof GlideModule)) {
                throw new RuntimeException("Expected instanceof GlideModule, but found: " + module);
              }
              return (GlideModule) module;
            }
          }