快速开发之xUtils(二)ViewUtils详细介绍

最新推荐文章于 2021-06-03 10:18:32 发布

i_a_jun

最新推荐文章于 2021-06-03 10:18:32 发布

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分类专栏： xUtils android 文章标签： android开发 xutils

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本文详细解析了 xUtils 框架中 View 和事件的注入机制，通过反射获取类字段并利用注解来绑定视图及事件监听器，简化 Android 开发过程中的常见任务。

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转载：http://www.apkbus.com/forum.php?mod=viewthread&tid=157641&highlight=xUtils

案例下载：http://download.youkuaiyun.com/detail/huningjun/8645595或者https://github.com/wyouflf/xUtils

xUtils可以减少我们很多重复性的工作，加快我们的开发速度。但是我们很有必要去了解一下它到底是怎么实现的。

因为需求总是变化的。可能有一天，我们需要去修改里面的一些东西。所以不但要知其然,还要知其所以然。

在view创建以后，xUtils只调用了以下这个方法，就实现了注入view和事件。

ViewUtils.inject(this,view); //注入view和事件

它到底做了什么事情呢？它的具体代码如下：

@SuppressWarnings("ConstantConditions")
private static void injectObject(Object handler, ViewFinder finder) {
// 注入view
Field[] fields = handler.getClass().getDeclaredFields();
if (fields != null && fields.length > 0) {
for (Field field : fields) {
//得到注解
ViewInject viewInject = field.getAnnotation(ViewInject.class);
if (viewInject != null) {
try {
//根据id找到view
View view = finder.findViewById(viewInject.value(), viewInject.parentId());
if (view != null) {
field.setAccessible(true);
//绑定view
field.set(handler, view);
}
} catch (Throwable e) {
LogUtils.e(e.getMessage(), e);
}
} else {
//得到注解
ResInject resInject = field.getAnnotation(ResInject.class);
if (resInject != null) {
try {
//根据id和资源类型load资源
Object res = ResLoader.loadRes(
resInject.type(), finder.getContext(), resInject.id());
if (res != null) {
field.setAccessible(true);
field.set(handler, res);
}
} catch (Throwable e) {
LogUtils.e(e.getMessage(), e);
}
} else {
//得到注解
PreferenceInject preferenceInject = field.getAnnotation(PreferenceInject.class);
if (preferenceInject != null) {
try {
根据id找到对应的Preference
Preference preference = finder.findPreference(preferenceInject.value());
if (preference != null) {
field.setAccessible(true);
field.set(handler, preference);
}
} catch (Throwable e) {
LogUtils.e(e.getMessage(), e);
}
}
}
}
}
}
// 注入事件
Method[] methods = handler.getClass().getDeclaredMethods();
if (methods != null && methods.length > 0) {
String eventName = OnClick.class.getCanonicalName();
String prefix = eventName.substring(0, eventName.lastIndexOf('.'));
DoubleKeyValueMap<ViewInjectInfo, Annotation, Method> info_annotation_method_map = new DoubleKeyValueMap<ViewInjectInfo, Annotation, Method>();
for (Method method : methods) {
Annotation[] annotations = method.getDeclaredAnnotations();
if (annotations != null && annotations.length > 0) {
for (Annotation annotation : annotations) {
Class<?> annType = annotation.annotationType();
if (annType.getAnnotation(EventBase.class) != null) {
if (annType.getCanonicalName().startsWith(prefix)) {
try {
// ProGuard：-keep class * extends java.lang.annotation.Annotation { *; }
Method valueMethod = annType.getDeclaredMethod("value");
Method parentIdMethod = null;
try {
parentIdMethod = annType.getDeclaredMethod("parentId");
} catch (Throwable e) {
}
Object values = valueMethod.invoke(annotation);
Object parentIds = parentIdMethod == null ? null : parentIdMethod.invoke(annotation);
int parentIdsLen = parentIds == null ? 0 : Array.getLength(parentIds);
int len = Array.getLength(values);
for (int i = 0; i < len; i++) {
ViewInjectInfo info = new ViewInjectInfo();
info.value = Array.get(values, i);
info.parentId = parentIdsLen > i ? (Integer) Array.get(parentIds, i) : 0;
info_annotation_method_map.put(info, annotation, method);
}
} catch (Throwable e) {
LogUtils.e(e.getMessage(), e);
}
} else {
ViewCustomEventListener listener = annotationType_viewCustomEventListener_map.get(annType);
if (listener != null) {
listener.setEventListener(handler, finder, annotation, method);
}
}
}
}
}
}
ViewCommonEventListener.setAllEventListeners(handler, finder, info_annotation_method_map);
}
}

复制代码

其实实现非常简单。首先是根据反射获得类的所有字段然后根据注解，得到控件的id，然后在view里找到控件。然后field.setAccessible(true);

field.set(handler,res);让声明的控件，和view里的控件关联起来。

资源类或根据资源id和资源类型加载到对应的资源。方法如下：ResLoader.loadRes(resInject.type(),finder.getContext(), resInject.id());

Preference也会根据id找到对应的值。

绑定事件的方式也是类似。代码如下：

@SuppressWarnings("ConstantConditions")
public static void setAllEventListeners(
Object handler,
ViewFinder finder,
DoubleKeyValueMap<ViewInjectInfo, Annotation, Method> info_annotation_method_map) {
for (ViewInjectInfo info : info_annotation_method_map.getFirstKeys()) {
ConcurrentHashMap<Annotation, Method> annotation_method_map = info_annotation_method_map.get(info);
for (Annotation annotation : annotation_method_map.keySet()) {
try {
Method method = annotation_method_map.get(annotation);
if (annotation instanceof OnClick) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//view.setOnClickListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnClickListener", OnClickListener.class, listener);
} else if (annotation instanceof OnLongClick) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//view.setOnLongClickListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnLongClickListener", OnLongClickListener.class, listener);
} else if (annotation instanceof OnFocusChange) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//view.setOnFocusChangeListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnFocusChangeListener", OnFocusChangeListener.class, listener);
} else if (annotation instanceof OnKey) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//view.setOnKeyListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnKeyListener", OnKeyListener.class, listener);
} else if (annotation instanceof OnTouch) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//view.setOnTouchListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnTouchListener", OnTouchListener.class, listener);
} else if (annotation instanceof OnItemClick) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//((AdapterView<?>) view).setOnItemClickListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnItemClickListener", OnItemClickListener.class, listener);
} else if (annotation instanceof OnItemLongClick) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//((AdapterView<?>) view).setOnItemLongClickListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnItemLongClickListener", OnItemLongClickListener.class, listener);
} else if (annotation instanceof OnChildClick) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//((ExpandableListView) view).setOnChildClickListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnChildClickListener", ExpandableListView.OnChildClickListener.class, listener);
} else if (annotation instanceof OnGroupClick) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//((ExpandableListView) view).setOnGroupClickListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnGroupClickListener", ExpandableListView.OnGroupClickListener.class, listener);
} else if (annotation instanceof OnGroupCollapse) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//((ExpandableListView) view).setOnGroupCollapseListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnGroupCollapseListener", ExpandableListView.OnGroupCollapseListener.class, listener);
} else if (annotation instanceof OnGroupExpand) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//((ExpandableListView) view).setOnGroupExpandListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnGroupExpandListener", ExpandableListView.OnGroupExpandListener.class, listener);
} else if (annotation instanceof OnCheckedChange) {
View view = finder.findViewByInfo(info);
if (view == null) break;
if (view instanceof RadioGroup) {
//((RadioGroup) view).setOnCheckedChangeListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnCheckedChangeListener", RadioGroup.OnCheckedChangeListener.class, listener);
} else if (view instanceof CompoundButton) {
//((CompoundButton) view).setOnCheckedChangeListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnCheckedChangeListener", CompoundButton.OnCheckedChangeListener.class, listener);
}
} else if (annotation instanceof OnPreferenceClick) {
Preference preference = finder.findPreference(info.value.toString());
if (preference == null) break;
//preference.setOnPreferenceClickListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(preference, "setOnPreferenceClickListener", Preference.OnPreferenceClickListener.class, listener);
} else if (annotation instanceof OnPreferenceChange) {
Preference preference = finder.findPreference(info.value.toString());
if (preference == null) break;
//preference.setOnPreferenceChangeListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(preference, "setOnPreferenceChangeListener", Preference.OnPreferenceChangeListener.class, listener);
} else if (annotation instanceof OnTabChange) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//((TabHost) view).setOnTabChangedListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "setOnTabChangedListener", TabHost.OnTabChangeListener.class, listener);
} else if (annotation instanceof OnScrollChanged) {
View view = finder.findViewByInfo(info);
if (view == null) break;
//view.getViewTreeObserver().addOnScrollChangedListener(new ViewCommonEventListener(handler, method));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method);
setEventListener(view, "addOnScrollChangedListener", ViewTreeObserver.OnScrollChangedListener.class, listener);
} else if (annotation instanceof OnScrollStateChanged) {
View view = finder.findViewByInfo(info);
if (view == null) break;
Method method0 = null, method1 = null;
ConcurrentHashMap<Annotation, Method> a_m_map = info_annotation_method_map.get(info);
for (Annotation a : a_m_map.keySet()) {
if (a instanceof OnScrollStateChanged) {
method0 = a_m_map.get(a);
} else if (a instanceof OnScroll) {
method1 = a_m_map.get(a);
}
}
//((AbsListView) view).setOnScrollListener(new ViewCommonEventListener(handler, method0, method1));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method0, method1);
setEventListener(view, "setOnScrollListener", AbsListView.OnScrollListener.class, listener);
} else if (annotation instanceof OnItemSelected) {
View view = finder.findViewByInfo(info);
if (view == null) break;
Method method0 = null, method1 = null;
ConcurrentHashMap<Annotation, Method> a_m_map = info_annotation_method_map.get(info);
for (Annotation a : a_m_map.keySet()) {
if (a instanceof OnItemSelected) {
method0 = a_m_map.get(a);
} else if (a instanceof OnNothingSelected) {
method1 = a_m_map.get(a);
}
}
//((AdapterView<?>) view).setOnItemSelectedListener(new ViewCommonEventListener(handler, method0, method1));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method0, method1);
setEventListener(view, "setOnItemSelectedListener", AbsListView.OnItemSelectedListener.class, listener);
} else if (annotation instanceof OnProgressChanged) {
View view = finder.findViewByInfo(info);
if (view == null) break;
Method method0 = null, method1 = null, method2 = null;
ConcurrentHashMap<Annotation, Method> a_m_map = info_annotation_method_map.get(info);
for (Annotation a : a_m_map.keySet()) {
if (a instanceof OnProgressChanged) {
method0 = a_m_map.get(a);
} else if (a instanceof OnStartTrackingTouch) {
method1 = a_m_map.get(a);
} else if (a instanceof OnStopTrackingTouch) {
method2 = a_m_map.get(a);
}
}
//((SeekBar) view).setOnSeekBarChangeListener(new ViewCommonEventListener(handler, method0, method1, method2));
ViewCommonEventListener listener = new ViewCommonEventListener(handler, method0, method1, method2);
setEventListener(view, "setOnSeekBarChangeListener", SeekBar.OnSeekBarChangeListener.class, listener);
}
} catch (Throwable e) {
LogUtils.e(e.getMessage(), e);
}
}
}
}
private static void setEventListener(Object view,
String setEventListenerMethod,
Class<?> eventListenerType,
ViewCommonEventListener listener) {
try {
Method setMethod = view.getClass().getMethod(setEventListenerMethod, eventListenerType);
if (setMethod != null) {
setMethod.invoke(view, listener);
}
} catch (Throwable e) {
LogUtils.e(e.getMessage(), e);
}
}