View注入框架：Butterknife简单使用

View注入框架下载地址

1.Activity Binging

通过@Bind凝视字段，Butter Knife能够通过View的ID自己主动找到并把对应的视图布局。

class ExampleActivity extends Activity {

@Bind(R.id.title) TextView title;

@Bind(R.id.subtitle) TextView subtitle;

@Bind(R.id.footer) TextView footer;

@Override public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.simple_activity);

ButterKnife.bind(this);

// TODO Use fields...

}

替换了缓慢的反射，通过自己主动生成代码来运行查询。你能够看到或者Debug调用@Bind的对象来生成代码。下图为上图所生成的代码。

public void bind(ExampleActivity activity) {

activity.subtitle = (android.widget.TextView) activity.findViewById(2130968578);

activity.footer = (android.widget.TextView) activity.findViewById(2130968579);

activity.title = (android.widget.TextView) activity.findViewById(2130968577);

}

2.Non Activity Binging

你能够指定Root View，从它中找到你@Bind的View

public class FancyFragment extends Fragment {

@Bind(R.id.button1) Button button1;

@Bind(R.id.button2) Button button2;

@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

View view = inflater.inflate(R.layout.fancy_fragment, container, false);

ButterKnife.bind(this, view);

// TODO Use fields...

return view;

}

3.Use in Adapter

在适配器列表中简化ViewHolder

public class MyAdapter extends BaseAdapter {

@Override public View getView(int position, View view, ViewGroup parent) {

ViewHolder holder;

if (view != null) {

holder = (ViewHolder) view.getTag();

} else {

view = inflater.inflate(R.layout.whatever, parent, false);

holder = new ViewHolder(view);

view.setTag(holder);

}

holder.name.setText("John Doe");

// etc...

return view;

}

static class ViewHolder {

@Bind(R.id.title) TextView name;

@Bind(R.id.job_title) TextView jobTitle;

public ViewHolder(View view) {

ButterKnife.bind(this, view);

}

4.View List

你能够将多个View分组存储到List或者Array中

@Bind({ R.id.first_name, R.id.middle_name, R.id.last_name })

List<EditText> nameViews;

The apply method allows you to act on all the views in a list at once.

ButterKnife.apply(nameViews, DISABLE);

ButterKnife.apply(nameViews, ENABLED, false);

Action and Setter interfaces allow specifying simple behavior.

static final ButterKnife.Action<View> DISABLE = new ButterKnife.Action<View>() {

@Override public void apply(View view, int index) {

view.setEnabled(false);

}

};

static final ButterKnife.Setter<View, Boolean> ENABLED = new ButterKnife.Setter<View, Boolean>() {

@Override public void set(View view, Boolean value, int index) {

view.setEnabled(value);

}

};

一个Android属性相同能够使用apply 方法

ButterKnife.apply(nameViews, View.ALPHA, 0.0f);

5.Listener Binging

Listeners也能够自己主动配置方法

@OnClick(R.id.submit)

public void submit(View view) {

// TODO submit data to server...

}

全部的Listener的參数是可选的

@OnClick(R.id.submit)

public void submit() {

// TODO submit data to server...

}

定义一个特定的类型它能够自己主动的转换

@OnClick(R.id.submit)

public void sayHi(Button button) {

button.setText("Hello!");

}

在同一个绑定事件处理中能够指定多个ID

@OnClick({ R.id.door1, R.id.door2, R.id.door3 })

public void pickDoor(DoorView door) {

if (door.hasPrizeBehind()) {

Toast.makeText(this, "You win!", LENGTH_SHORT).show();

} else {

Toast.makeText(this, "Try again", LENGTH_SHORT).show();

}

自己定义视图能够绑定自己的事件监听而且不指定ID

public class FancyButton extends Button {

@OnClick

public void onClick() {

// TODO do something!

}

6.Binging Reset

Fragments 比Activity有不同的View生命周期，在Fragmrnt 的onCreateView方法中绑定，onDestroyView方法中销毁Views。Butter
Knife有unbind 方法自己主动去做。

public class FancyFragment extends Fragment {

@Bind(R.id.button1) Button button1;

@Bind(R.id.button2) Button button2;

@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

View view = inflater.inflate(R.layout.fancy_fragment, container, false);

ButterKnife.bind(this, view);

// TODO Use fields...

return view;

}

@Override public void onDestroyView() {

super.onDestroyView();

ButterKnife.unbind(this);

}

7.Optional Binging

默认情况下,@Bind和侦听器绑定都是必需的。假设目标View无法找到它将抛出一个异常。

为了抑制这样的习惯常见了可选绑定。@Nullable注解加入到字段或者方法中

笔记：怎样注解前都支持@Nullable注解（官方鼓舞这种行为）

@Nullable @Bind(R.id.might_not_be_there) TextView mightNotBeThere;

@Nullable @OnClick(R.id.maybe_missing) void onMaybeMissingClicked() {

// TODO ...

}

8.Multi-Method Listeners

方法凝视对应的监听器有多个回调能够绑定到不论什么当中之中的一个。每个凝视都绑定到一个默认的回调。使用callback 參数指定一个替代

@OnItemSelected(R.id.list_view)

void onItemSelected(int position) {

// TODO ...

}

@OnItemSelected(value = R.id.maybe_missing, callback = NOTHING_SELECTED)

void onNothingSelected() {

// TODO ...

}

9.Bonus

还包括findById方法的简化依旧须要知道Views在哪个view、Activity、Dialog。

它使用泛型来判断返回类型,并自己主动运行。

View view = LayoutInflater.from(context).inflate(R.layout.thing, null);

TextView firstName = ButterKnife.findById(view, R.id.first_name);

TextView lastName = ButterKnife.findById(view, R.id.last_name);

ImageView photo = ButterKnife.findById(view, R.id.photo);

注意：

使用Android Studio 须要在Gradle文件里加入

compile 'com.jakewharton:butterknife:(insert latest version)'

混淆编译的时候须要在proguard文件里加入

-keep class butterknife.** { *; }

-dontwarn butterknife.internal.**

-keep class **$$ViewBinder { *; }

-keepclasseswithmembernames class * {

    @butterknife.* <fields>;

}

-keepclasseswithmembernames class * {

    @butterknife.* <methods>;

}

官网：http://jakewharton.github.io/butterknife/