ButterKnife初级用法
16lz
2021-01-23
ButterKnife是为Android提供的注解式框架,可以简化代码的编写,比如:
class ExampleActivity extends Activity { TextView title; TextView subtitle; TextView footer; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.simple_activity); title = (TextView) findViewById(R.id.title); subtitle = (TextView) findViewById(R.id.subtitle); footer = (TextView) findViewById(R.id.footer); // TODO Use views... }}
如果用框架写的话,则变为:
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... }
从这个例子也可以看出在一个activity中如何完成控件的绑定,首先bind方法是必须的,然后用@Bind可以完成各个控件的绑定,在AS中可以直接用插件生成,非常方便 下面是资源文件的绑定:
class ExampleActivity extends Activity { @BindString(R.string.title) String title; @BindDrawable(R.drawable.graphic) Drawable graphic; @BindColor(R.color.red) int red; // int or ColorStateList field @BindDimen(R.dimen.spacer) Float spacer; // int (for pixel size) or float (for exact value) field // ...}
如果不是在一个Activity中,框架的用法有小小的区别: 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; }}
在优化ListView时经常在adapter用到ViewHolder,对该类Butterknife也有相应的用法: 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); } }}
给监听器注入: @OnClick(R.id.submit)public void submit(View view) { // TODO submit data to server...}
参数view有没有都无所谓, 当然,也可以为多个控件设置监听器注入:
@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(); }}
方法中也可以根据id不同来设置不同监听事件 由于Fragment与Activity有不同的生命周期,如果要绑定一个Fragment在onCreateView方法中时,需要将试图设置为空在onDestroy的时候,用unbind方法即可
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); }}
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