ButterKnife是一个通过对Android View添加注解的方式来提高开发效率的开源库。
1.配置
在项目中配置ButterKnife有下面几种方式:
JAR
旧式导jar包:Butter Knife v6.1.0 JAR
MAVEN
如果你使用maven，可以添加butterknife库作为依赖
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| <dependency>
<groupId>com.jakewharton</groupId>
<artifactId>butterknife</artifactId>
<version>6.1.0</version>
</dependency>
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GRADLE
如果你使用gradle构建android项目（Android Studio默认构建方式），则可以在app -> build.gradle -> dependencies节点添加下面配置
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| compile 'com.jakewharton:butterknife:6.1.0'
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如果项目编译时出现类似InvalidPackage: Package not included in Android错误，则需要在app -> build.gradle -> android节点添加下面配置(不过我没出现这错误…)
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| android {
...
lintOptions {
disable 'InvalidPackage'
}
packagingOptions {
exclude 'META-INF/services/javax.annotation.processing.Processor'
}
}
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2.使用
2.1 ACTIVITY INJECTION
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| class ExampleActivity extends Activity {
@InjectView(R.id.title) TextView title;
@InjectView(R.id.subtitle) TextView subtitle;
@InjectView(R.id.footer) TextView footer;
@Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.simple_activity);
ButterKnife.inject(this);
}
}
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2.2 NON-ACTIVITY INJECTION
也可以对除Activity之外的view对象进行注入，不过要在获取到view root对象后。
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| public class FancyFragment extends Fragment {
@InjectView(R.id.button1) Button button1;
@InjectView(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.inject(this, view);
return view;
}
@Override public void onDestroyView() {
super.onDestroyView();
ButterKnife.reset(this);
}
}
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2.3 ViewHolder INJECTION
也可以简化list adapter中的View Holder模式。
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| 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");
return view;
}
static class ViewHolder {
@InjectView(R.id.title) TextView name;
@InjectView(R.id.job_title) TextView jobTitle;
public ViewHolder(View view) {
ButterKnife.inject(this, view);
}
}
}
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2.4 LISTENER INJECTION
可以对事件监听进行注入(方法的参数可以按需添加)
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| @OnClick(R.id.submit)
public void submit() {
}
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可以一次指定多个id，同时加事件
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| @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();
}
}
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可以给listview的item点击事件添加注入
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| @OnItemClick(R.id.list_view)
void onItemClick(AdapterView<?> parent, View view, int position, long id) {
}
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自定义的view不用指定具体id也可以绑定它的listeners
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| public class FancyButton extends Button {
@OnClick
public void onClick() {
}
}
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2.5 OPTIONAL INJECTIONS
通常情况下不会出现the target view cannot be found情况，但为了避免出现而报异常，可以在变量或者方法前面加上 @Optional 注解
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| @Optional @InjectView(R.id.might_not_be_there) TextView mightNotBeThere;
@Optional @OnClick(R.id.maybe_missing) void onMaybeMissingClicked() {
}
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2.6 其他
有一些View, Activity, or Dialog可能还是会去find views id，butterknife提供了findById方法，它会自动强转为正确类型。
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| 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);
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3.混淆
如果你在打包apk时需要对代码进行混淆处理，这时为了避免那些使用了butterknife注解的文件被认为无用而删除，可以在app -> proguard-rules.pro 文件中添加下面混淆规则：
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-keep class butterknife.** { *; }
-dontwarn butterknife.internal.**
-keep class **$$ViewInjector { *; }
-keepclasseswithmembernames class * {
@butterknife.* <fields>;
}
-keepclasseswithmembernames class * {
@butterknife.* <methods>;
}
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更多相关内容请查看源码和官方说明:
ButterKnife Github
ButterKnife Introduction