1 Glide 使用 ---4.11.0

導(dǎo)入庫(kù)

implementation 'com.github.bumptech.glide:glide:4.11.0'
    annotationProcessor 'com.github.bumptech.glide:compiler:4.11.0'

1.1 簡(jiǎn)單使用

class GlideTest : AppCompatActivity() {
    lateinit var binding: ActivityGlideTestBinding
    val imgUrl = "https://cn.bing.com/sa/simg/hpb/LaDigue_EN-CA1115245085_1920x1080.jpg"
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_glide_test)
        binding.showImg.setOnClickListener {

            Glide.with(this).load(imgUrl).into(binding.contentImg)

        }
    }
}

1.2 其他部分用法

val doc1 = """
    Glide 加載圖片的方式
    // 加載本地圖片
    File file = new File(getExternalCacheDir() + "/image.jpg");
    Glide.with(this).load(file).into(imageView);

    // 加載應(yīng)用資源
    int resource = R.drawable.image;
    Glide.with(this).load(resource).into(imageView);

    // 加載二進(jìn)制流
    byte[] image = getImageBytes();
    Glide.with(this).load(image).into(imageView);

    // 加載Uri對(duì)象
    Uri imageUri = getImageUri();
    Glide.with(this).load(imageUri).into(imageView);
"""

val doc2 = """
    Glide 占位圖，和一些屬性實(shí)例
    Glide.with(this)
     .load(url)
     .asBitmap()
     .placeholder(R.drawable.loading)
     .error(R.drawable.error)
     .diskCacheStrategy(DiskCacheStrategy.NONE)
     .into(imageView);
     
    Glide.with(this).load(url)
     .asGif()
     .placeholder(R.drawable.loading).error(R.drawable.error).diskCacheStrategy(DiskCacheStrategy.NONE)
     .into(imageView);
     
    Glide.with(this).load(url).placeholder(R.drawable.loading.error(R.drawable.error).diskCacheStrategy(DiskCacheStrategy.NONE)
     .override(100, 100)
     .into(imageView);
"""

2 三部曲with柿祈，load绑莺，into

2.1

第一步

Glide#width(xxxx) 目標(biāo)獲取 RequestManager

第二步
Glide#load(xxx) 目標(biāo)獲取 RequestBuilder

第三步
Glide#into(xxx) 獲取和處理Target

1. 運(yùn)行隊(duì)列暖眼，等待隊(duì)列
2. 活動(dòng)緩存
3. 內(nèi)存緩存
4. 網(wǎng)絡(luò)模型

2.1.1 with

監(jiān)聽(tīng)Activity/Fragment生命周期

當(dāng)我們的Fragment或Activity不可見(jiàn)的時(shí)候暫停請(qǐng)求，當(dāng)我們的Fragment或Activity可見(jiàn)的時(shí)候回復(fù)請(qǐng)求

處理前臺(tái)可見(jiàn)的 Activity / Fragment纺裁，提高資源利用率;
在有必要時(shí)釋放資源以避免在應(yīng)用在后臺(tái)時(shí)被殺死诫肠，提高穩(wěn)定性;

Glide#with(params)
with會(huì)有很多重載方法，params參數(shù)有這些種類：(FragmentActivity欺缘，androidx.fragment.app.Fragment栋豫，android.app.Fragment,View)
通過(guò)獲取RequestManagerRetriever 進(jìn)行檢索

RequestManagerRetriever#get方法 多個(gè)重載

通過(guò)源碼，我們會(huì)看到四個(gè)重載方法

public RequestManager get(@NonNull Context context)

public RequestManager get(@NonNull FragmentActivity activity)

public RequestManager get(@NonNull Fragment fragment)

public RequestManager get(@NonNull Activity activity)

public RequestManager get(@NonNull View view)

通過(guò)這些發(fā)放的分析谚殊，我們得出下面的分析

生命周期的作用域(1.Application丧鸯， 2.Activity， 3.Fragment)

一共分為兩種:
第一種是作用域Application嫩絮，它的生命周期是全局 的丛肢，不搞空白Fragment綁定Activity/Fragment
第二種是作用域非Application，它的生命周期是絮记，專門搞空白Fragment綁定 Activity/Fragment

生成默認(rèn)隱藏fragment 摔踱，我們發(fā)現(xiàn)有著幾個(gè)方法

private RequestManager supportFragmentGet(
      @NonNull Context context,
      @NonNull FragmentManager fm,
      @Nullable Fragment parentHint,
      boolean isParentVisible)

private RequestManager fragmentGet(
      @NonNull Context context,
      @NonNull android.app.FragmentManager fm,
      @Nullable android.app.Fragment parentHint,
      boolean isParentVisible)

supportFragmentGet---->getSupportRequestManagerFragment
獲取SupportRequestManagerFragment (Tag:FRAGMENT_TAG)的fragment

private SupportRequestManagerFragment getSupportRequestManagerFragment(
      @NonNull final FragmentManager fm, @Nullable Fragment parentHint, boolean isParentVisible) {
    SupportRequestManagerFragment current =
        (SupportRequestManagerFragment) fm.findFragmentByTag(FRAGMENT_TAG);
    if (current == null) {
      current = pendingSupportRequestManagerFragments.get(fm);
      if (current == null) {
        current = new SupportRequestManagerFragment();
        current.setParentFragmentHint(parentHint);
        if (isParentVisible) {
          current.getGlideLifecycle().onStart();
        }
        pendingSupportRequestManagerFragments.put(fm, current);
        fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();
        handler.obtainMessage(ID_REMOVE_SUPPORT_FRAGMENT_MANAGER, fm).sendToTarget();
      }
    }
    return current;
  }

fragmentGet---->getRequestManagerFragment
獲取RequestManagerFragment (Tag:FRAGMENT_TAG)的fragment

private RequestManagerFragment getRequestManagerFragment(
      @NonNull final android.app.FragmentManager fm,
      @Nullable android.app.Fragment parentHint,
      boolean isParentVisible) {
    RequestManagerFragment current = (RequestManagerFragment) fm.findFragmentByTag(FRAGMENT_TAG);
    if (current == null) {
      current = pendingRequestManagerFragments.get(fm);
      if (current == null) {
        current = new RequestManagerFragment();
        current.setParentFragmentHint(parentHint);
        if (isParentVisible) {
          current.getGlideLifecycle().onStart();
        }
        pendingRequestManagerFragments.put(fm, current);
        fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();
        handler.obtainMessage(ID_REMOVE_FRAGMENT_MANAGER, fm).sendToTarget();
      }
    }
    return current;
  }

生命周期的綁定

【記錄保存】 FragmentManager -SupportRequestManagerFragment

RequestManagerRetriever .java

final Map<FragmentManager, SupportRequestManagerFragment> pendingSupportRequestManagerFragments =
new HashMap<>();

supportFragmentGet----getSupportRequestManagerFragment

1. 從FragmentManager中獲取SupportRequestManagerFragment

SupportRequestManagerFragment current =
        getSupportRequestManagerFragment(fm, parentHint, isParentVisible);

2.從該 Fragment 中獲取 RequestManager

RequestManager requestManager =current.getRequestManager();

3.首次獲取虐先，則實(shí)例化 RequestManager

------> getSupportRequestManagerFragment
1.1 嘗試獲取 FRAGMENT_TAG 對(duì)應(yīng)的 Fragment
1.2 嘗試從臨時(shí)記錄中獲取Fragment
如果為獲取到
1.3 current==null---實(shí)例化 Fragment

1.3.1 創(chuàng)建對(duì)象SupportRequestManagerFragment
1.3.2 如果父層可見(jiàn)怨愤，則調(diào)用 onStart() 生命周期
1.3.3 臨時(shí)記錄映射關(guān)系pendingSupportRequestManagerFragments.put(fm, current)
1.3.4 提交 Fragment 事務(wù)
1.3.5 post 一個(gè)消息
handler.obtainMessage(ID_REMOVE_SUPPORT_FRAGMENT_MANAGER, fm).sendToTarget();

-》post 一個(gè)消息分析: RequestManagerRetriever 本身實(shí)現(xiàn)了Handler的callback
handleMessage中

case ID_REMOVE_SUPPORT_FRAGMENT_MANAGER:
        FragmentManager supportFm = (FragmentManager) message.obj;
        key = supportFm;
        removed = pendingSupportRequestManagerFragments.remove(supportFm);
        break;

就是為了避免 SupportRequestManagerFragment 在一個(gè)作用域中重復(fù)創(chuàng)建。

因?yàn)?commitAllowingStateLoss() 是將事務(wù) post 到消息隊(duì)列中的蛹批，也就是說(shuō)撰洗，事 務(wù)是異步處理的篮愉，而不是同步處理的。假設(shè)沒(méi)有臨時(shí)保存記錄差导，一旦在事務(wù)異步等待 執(zhí)行時(shí)調(diào)用了 Glide.with(...) 若河，就會(huì)在該作用域中重復(fù)創(chuàng)建 Fragment勺择。

生命周期的監(jiān)聽(tīng)機(jī)制

Glide內(nèi)部會(huì)在 Activity/Fragment生命周期監(jiān)聽(tīng)，網(wǎng)絡(luò)變化監(jiān)聽(tīng)，自動(dòng)取消加 載或者重新加載

框架為每個(gè)Activity 和 Fragment 作用域創(chuàng)建了 一個(gè)無(wú)UI的Fragment

分析這個(gè)空Fragment---》 SupportRequestManagerFragment.java
看下我們比較關(guān)心的代碼

ActivityFragmentLifecycle lifecycle

public SupportRequestManagerFragment() {
    this(new ActivityFragmentLifecycle());
  }

  
  public SupportRequestManagerFragment(@NonNull ActivityFragmentLifecycle lifecycle) {
    this.lifecycle = lifecycle;
  }

 
  public void setRequestManager(@Nullable RequestManager requestManager) {
    this.requestManager = requestManager;
  }

 @Override
  public void onStart() {
    super.onStart();
    lifecycle.onStart();
  }

  @Override
  public void onStop() {
    super.onStop();
    lifecycle.onStop();
  }

  @Override
  public void onDestroy() {
    super.onDestroy();
    lifecycle.onDestroy();
    unregisterFragmentWithRoot();
  }

回溯一下坝辫，RequestManagerRetriever.java 和 RequestManager.java

1. 實(shí)例化RequestManager

Glide glide = Glide.get(context);
      requestManager =
          factory.build(
              glide, current.getGlideLifecycle(), current.getRequestManagerTreeNode(), context);

2. RequestManager 工廠

public interface RequestManagerFactory {
    @NonNull
    RequestManager build(
        @NonNull Glide glide,
        @NonNull Lifecycle lifecycle,
        @NonNull RequestManagerTreeNode requestManagerTreeNode,
        @NonNull Context context);
  }

3. 默認(rèn)工廠接口實(shí)現(xiàn)

private static final RequestManagerFactory DEFAULT_FACTORY =
      new RequestManagerFactory() {
        @NonNull
        @Override
        public RequestManager build(
            @NonNull Glide glide,
            @NonNull Lifecycle lifecycle,
            @NonNull RequestManagerTreeNode requestManagerTreeNode,
            @NonNull Context context) {
          return new RequestManager(glide, lifecycle, requestManagerTreeNode, context);
        }
      };

RequestManager.java 源碼我們關(guān)心的部分

final Lifecycle lifecycle;

public RequestManager(
      @NonNull Glide glide,
      @NonNull Lifecycle lifecycle,
      @NonNull RequestManagerTreeNode treeNode,
      @NonNull Context context) {
......
    this.lifecycle = lifecycle;
    this.requestTracker = requestTracker;// 生命周期回調(diào)
。仍劈。娄猫。
if (Util.isOnBackgroundThread()) {
      mainHandler.post(addSelfToLifecycle);
    } else {// 添加監(jiān)聽(tīng)
      lifecycle.addListener(this);
    }
。外冀。寡键。

public synchronized void onDestroy() {
    targetTracker.onDestroy();
    ......
    lifecycle.removeListener(this);//remove 監(jiān)聽(tīng)
  }
}

實(shí)例化 RequestManager 時(shí)需要一個(gè) Lifecycle對(duì)象，這個(gè)對(duì)象是 在無(wú)界面 Fragment 中創(chuàng)建的雪隧，當(dāng) Fragment 的生命周期變化時(shí)西轩，就是通過(guò)這個(gè) Lifecycle 對(duì)象將事件分發(fā)到RequestManager

生命周期的回調(diào)

RequestsManger 收到的回調(diào)ConnectivityMonitor

public interface LifecycleListener {
    void onStart();
    void onStop();
    void onDestroy();
}

Activity/Fragment 不可見(jiàn)時(shí)暫停請(qǐng)求 (onStop() ) 函數(shù) Activity/Fragment 可見(jiàn)時(shí)恢復(fù)請(qǐng)求 (onStart() ) 函數(shù) Activity/Fragment 銷毀時(shí)銷毀請(qǐng)求 (onDestroy() )函數(shù)

---》 RequestManger 操作 requestTracker

@Override
  public synchronized void onStop() {
    pauseRequests();
    targetTracker.onStop();
  }

@Override
  public synchronized void onStart() {
    resumeRequests();
    targetTracker.onStart();
  }

  public synchronized void resumeRequests() {
    requestTracker.resumeRequests();
  }

public synchronized void pauseRequests() {
    requestTracker.pauseRequests();
  }

@Override
  public synchronized void onDestroy() {
    targetTracker.onDestroy();
    for (Target<?> target : targetTracker.getAll()) {
      clear(target);
    }
    targetTracker.clear();
    requestTracker.clearRequests();
    lifecycle.removeListener(this);
    lifecycle.removeListener(connectivityMonitor);
    mainHandler.removeCallbacks(addSelfToLifecycle);
    glide.unregisterRequestManager(this);
  }