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@yudesong 2018-02-12T03:13:14.000000Z 字数 6894 阅读 703

xUtils 源码解析(一)

xUtils

本文使是以xUtils 2.6的版本来解析源码，可分为以下几个部分：

1. cache

屏幕快照 2018-01-28 11.27.34.png

屏幕快照 2018-01-28 12.01.54.png
首先来看看FileNameGenerator这个接口，其中有一个方法generate方法，生成文件名称,MD5FileNameGenerator实现了该方法，并且采用MD5算法。

  1. public String generate(String key) {
  2.     String cacheKey;
  3.     try {
  4.         final MessageDigest mDigest = MessageDigest.getInstance("MD5");
  5.         mDigest.update(key.getBytes());
  6.         cacheKey = bytesToHexString(mDigest.digest());
  7.     } catch (NoSuchAlgorithmException e) {
  8.         cacheKey = String.valueOf(key.hashCode());
  9.     }
  10.     return cacheKey;
  11. }
  13. private String bytesToHexString(byte[] bytes) {
  14.     StringBuilder sb = new StringBuilder();
  15.     for (int i = 0; i < bytes.length; i++) {
  16.        String hex = Integer.toHexString(0xFF & bytes[i]);
  17.         if (hex.length() == 1) {
  18.             sb.append('0');
  19.         }
  20.         sb.append(hex);
  21.     }
  22.     return sb.toString();
  23. }

KeyExpiryMap继承自ConcurrentHashMap，存储类型为范型其中Long保存了该key的保存的时间戳。

  1. @Override
  2. public synchronized Long put(K key, Long expiryTimestamp) {
  3.     if (this.containsKey(key)) {
  4.         this.remove(key);
  5.     }
  6.     return super.put(key, expiryTimestamp);
  7. }
  9. @Override
  10. public synchronized boolean containsKey(Object key) {
  11.     boolean result = false;
  12.     Long expiryTimestamp = super.get(key);
  13.     if (expiryTimestamp != null && System.currentTimeMillis() < expiryTimestamp) {
  14.         result = true;
  15.     } else {
  16.     this.remove(key);
  17.     }
  18.     return result;
  19. }

LruMemoryCache 为实现了最近最少使用算法，可参考这边博客Java 最近最少使用算法(LRU)。其内部保存了一个LinkedHashMap、KeyExpiryMap对象的应用。

  1. public final V get(K key) {
  2.     if (key == null) {
  3.         throw new NullPointerException("key == null");
  4.     }
  6.     V mapValue;
  7.     synchronized (this) {
  8.         // If expired, remove the entry.
  9.         if (!keyExpiryMap.containsKey(key)) {
  10.             this.remove(key);
  11.             return null;
  12.         }
  13.         mapValue = map.get(key);
  14.         if (mapValue != null) {
  15.             hitCount++;
  16.             return mapValue;
  17.         }
  18.         missCount++;
  19.     }
  21.     /*
  22.      * Attempt to create a value. This may take a long time, and the map
  23.      * may be different when create() returns. If a conflicting value was
  24.      * added to the map while create() was working, we leave that value in
  25.      * the map and release the created value.
  26.      */
  28.     V createdValue = create(key);
  29.     if (createdValue == null) {
  30.         return null;
  31.     }
  33.     synchronized (this) {
  34.         createCount++;
  35.         mapValue = map.put(key, createdValue);
  37.         if (mapValue != null) {
  38.             // There was a conflict so undo that last put
  39.             map.put(key, mapValue);
  40.         } else {
  41.             size += safeSizeOf(key, createdValue);
  42.         }
  43.     }
  45.     if (mapValue != null) {
  46.         entryRemoved(false, key, createdValue, mapValue);
  47.         return mapValue;
  48.     } else {
  49.         trimToSize(maxSize);
  50.         return createdValue;
  51.     }
  52. }
  54. public final V put(K key, V value) {
  55.     return put(key, value, Long.MAX_VALUE);
  56. }
  58. public final V put(K key, V value, long expiryTimestamp) {
  59.     if (key == null || value == null) {
  60.         throw new NullPointerException("key == null || value == null");
  61.     }
  63.     V previous;
  64.     synchronized (this) {
  65.         putCount++;
  66.         size += safeSizeOf(key, value);
  67.         previous = map.put(key, value);
  68.         keyExpiryMap.put(key, expiryTimestamp);
  69.         if (previous != null) {
  70.             size -= safeSizeOf(key, previous);
  71.         }
  72.     }
  74.     if (previous != null) {
  75.         entryRemoved(false, key, previous, value);
  76.     }
  78.     trimToSize(maxSize);
  79.     return previous;
  80. }
  82. private void trimToSize(int maxSize) {
  83.     while (true) {
  84.        K key;
  85.        V value;
  86.        synchronized (this) {
  87.             if (size <= maxSize || map.isEmpty()) {
  88.                 break;
  89.             }
  91.             Map.Entry<K, V> toEvict = map.entrySet().iterator().next();
  92.             key = toEvict.getKey();
  93.             value = toEvict.getValue();
  94.             map.remove(key);
  95.             keyExpiryMap.remove(key);
  96.             size -= safeSizeOf(key, value);
  97.             evictionCount++;
  98.        }
  99.        entryRemoved(true, key, value, null);
  100.      }
  101. }
  103. public final V remove(K key) {
  104.     if (key == null) {
  105.         throw new NullPointerException("key == null");
  106.     }
  108.     V previous;
  109.     synchronized (this) {
  110.         previous = map.remove(key);
  111.         keyExpiryMap.remove(key);
  112.         if (previous != null) {
  113.             size -= safeSizeOf(key, previous);
  114.         }
  115.     }
  117.     if (previous != null) {
  118.         entryRemoved(false, key, previous, null);
  119.     }
  120.     return previous;
  121. }

2. view

ContentView 、ViewInject、OnClick注解

  1. @Target(ElementType.TYPE)
  2. @Retention(RetentionPolicy.RUNTIME)
  3. public @interface ContentView {
  4.     int value();
  5. }
  7. @Target(ElementType.FIELD)
  8. @Retention(RetentionPolicy.RUNTIME)
  9. public @interface ViewInject {
  10.     int value();
  11.     /* parent view id */
  12.     int parentId() default 0;
  13. }
  15. @Target(ElementType.METHOD)
  16. @Retention(RetentionPolicy.RUNTIME)
  17. @EventBase(
  18.         listenerType = View.OnClickListener.class,
  19.         listenerSetter = "setOnClickListener",
  20.         methodName = "onClick")
  21. public @interface OnClick {
  22.     int[] value();
  23.     int[] parentId() default 0;
  24. }

最主要的类就是ViewUtils。

  1. public static void inject(Activity activity) {
  2.     injectObject(activity, new ViewFinder(activity));
  3. }
  5. @SuppressWarnings("ConstantConditions")
  6. private static void injectObject(Object handler, ViewFinder finder) {
  7.     Class<?> handlerType = handler.getClass();
  8.     // inject ContentView
  9.     ContentView contentView = handlerType.getAnnotation(ContentView.class);
  10.     if (contentView != null) {
  11.         try {
  12.             Method setContentViewMethod = handlerType.getMethod("setContentView", int.class);
  13.             setContentViewMethod.invoke(handler, contentView.value());
  14.         } catch (Throwable e) {
  15.             LogUtils.e(e.getMessage(), e);
  16.         }
  17.     }
  19.     // inject view
  20.     Field[] fields = handlerType.getDeclaredFields();
  21.     if (fields != null && fields.length > 0) {
  22.         for (Field field : fields) {
  23.             ViewInject viewInject = field.getAnnotation(ViewInject.class);
  24.             if (viewInject != null) {
  25.                 try {
  26.                     View view = finder.findViewById(viewInject.value(), viewInject.parentId());
  27.                     if (view != null) {
  28.                         field.setAccessible(true);
  29.                         field.set(handler, view);
  30.                     }
  31.                 } catch (Throwable e) {
  32.                     LogUtils.e(e.getMessage(), e);
  33.                 }
  34.             } else {
  35.                 ResInject resInject = field.getAnnotation(ResInject.class);
  36.                 if (resInject != null) {
  37.                     try {
  38.                         Object res = ResLoader.loadRes(
  39.                                 resInject.type(), finder.getContext(), resInject.id());
  40.                         if (res != null) {
  41.                             field.setAccessible(true);
  42.                             field.set(handler, res);
  43.                         }
  44.                     } catch (Throwable e) {
  45.                         LogUtils.e(e.getMessage(), e);
  46.                     }
  47.                 } else {
  48.                     PreferenceInject preferenceInject = field.getAnnotation(PreferenceInject.class);
  49.                     if (preferenceInject != null) {
  50.                         try {
  51.                             Preference preference = finder.findPreference(preferenceInject.value());
  52.                             if (preference != null) {
  53.                                 field.setAccessible(true);
  54.                                 field.set(handler, preference);
  55.                             }
  56.                         } catch (Throwable e) {
  57.                             LogUtils.e(e.getMessage(), e);
  58.                         }
  59.                     }
  60.                 }
  61.             }
  62.         }
  63.     }
  64.     // inject event
  65.     Method[] methods = handlerType.getDeclaredMethods();
  66.     if (methods != null && methods.length > 0) {
  67.         for (Method method : methods) {
  68.             Annotation[] annotations = method.getDeclaredAnnotations();
  69.             if (annotations != null && annotations.length > 0) {
  70.                 for (Annotation annotation : annotations) {
  71.                     Class<?> annType = annotation.annotationType();
  72.                     if (annType.getAnnotation(EventBase.class) != null) {
  73.                         method.setAccessible(true);
  74.                         try {
  75.                             // ProGuard：-keep class * extends java.lang.annotation.Annotation { *; }
  76.                             Method valueMethod = annType.getDeclaredMethod("value");
  77.                             Method parentIdMethod = null;
  78.                             try {
  79.                                 parentIdMethod = annType.getDeclaredMethod("parentId");
  80.                             } catch (Throwable e) {
  81.                             }
  82.                             Object values = valueMethod.invoke(annotation);
  83.                             Object parentIds = parentIdMethod == null ? null : parentIdMethod.invoke(annotation);
  84.                             int parentIdsLen = parentIds == null ? 0 : Array.getLength(parentIds);
  85.                             int len = Array.getLength(values);
  86.                             for (int i = 0; i < len; i++) {
  87.                                 ViewInjectInfo info = new ViewInjectInfo();
  88.                                 info.value = Array.get(values, i);
  89.                                 info.parentId = parentIdsLen > i ? (Integer) Array.get(parentIds, i) : 0;
  90.                                EventListenerManager.addEventMethod(finder, info, annotation, handler, method);
  91.                             }
  92.                         } catch (Throwable e) {
  93.                            LogUtils.e(e.getMessage(), e);
  94.                         }
  95.                     }
  96.                 }
  97.             }
  98.         }
  99.     }
  100. }

其中ViewFinder类如下：
```
public class ViewFinder {

private View view;
private Activity activity;
public ViewFinder(View view) {
    this.view = view;
}

public ViewFinder(Activity activity) {
    this.activity = activity;
}

......
public View findViewById(int id, int pid) {
    View pView = null;
    if (pid > 0) {
        pView = this.findViewById(pid);
    }

    View view = null;
    if (pView != null) {
        view = pView.findViewById(id);
    } else {
        view = this.findViewById(id);
    }
    return view;
}

@SuppressWarnings("deprecation")
public Preference findPreference(CharSequence key) {
    return preferenceGroup == null ? preferenceActivity.findPreference(key) : preferenceGroup.findPreference(key);
}

}
```

参考文章
1.trimToSize 用法

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