ButterKnife使用小结

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

Github主页：https://github.com/JakeWharton/butterknife

这个注解框架强大好用，国外牛逼博主  JakeWharton 杰作，下面 代码片段时最新的 7.01.jar，跟以前的使用变化很大。

直接下载jar包，引入项目就行，基本使用代码片如下：

package com.example.butterknife;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.AlphaAnimation;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import butterknife.ButterKnife;
import butterknife.Bind;
import butterknife.OnClick;
import butterknife.OnItemClick;
import butterknife.OnLongClick;
import java.util.List;

import static android.widget.Toast.LENGTH_SHORT;

public class SimpleActivity extends Activity {

//一个可以实现全局View都调用的方法，需要用集合或者数组来传入View对象
  private static final ButterKnife.Action<View> ALPHA_FADE = new ButterKnife.Action<View>() {
    @Override public void apply(View view, int index) {
      AlphaAnimation alphaAnimation = new AlphaAnimation(0, 1);
      alphaAnimation.setFillBefore(true);
      alphaAnimation.setDuration(500);
      alphaAnimation.setStartOffset(index * 100);
      view.startAnimation(alphaAnimation);
    }
  };
//最基本的注解单个View对象
  @Bind(R.id.title) TextView title;
  @Bind(R.id.subtitle) TextView subtitle;
  @Bind(R.id.hello) Button hello;
  @Bind(R.id.list_of_things) ListView listOfThings;
  @Bind(R.id.footer) TextView footer;
//扩展，可以注解多个View对象
  @Bind({ R.id.title, R.id.subtitle, R.id.hello })
  List<View> headerViews;

  private SimpleAdapter adapter;
//实现VIew的onclick方法，Id用onclick注解以后，后面直接方法名就可以使用，不需要再二次调用sayHello方法
  @OnClick(R.id.hello) void sayHello() {
    Toast.makeText(this, "Hello, views!", LENGTH_SHORT).show();
    ButterKnife.apply(headerViews, ALPHA_FADE);
  }
//同理onclick
  @OnLongClick(R.id.hello) boolean sayGetOffMe() {
    Toast.makeText(this, "Let go of me!", LENGTH_SHORT).show();
    return true;
  }

  @OnItemClick(R.id.list_of_things) void onItemClick(int position) {
    Toast.makeText(this, "You clicked: " + adapter.getItem(position), LENGTH_SHORT).show();
  }

  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.simple_activity);    //初始化Butter Knife
    ButterKnife.bind(this);

    // Contrived code to use the bound fields.
    title.setText("Butter Knife");
    subtitle.setText("Field and method binding for Android views.");
    footer.setText("by Jake Wharton");
    hello.setText("Say Hello");

    adapter = new SimpleAdapter(this);
    listOfThings.setAdapter(adapter);
  }
}

开发中最常用的适配器，用注解代码如下：

package com.example.butterknife;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import butterknife.ButterKnife;
import butterknife.Bind;

public class SimpleAdapter extends BaseAdapter {
  private static final String[] CONTENTS =
      "The quick brown fox jumps over the lazy dog".split(" ");

  private final LayoutInflater inflater;

  public SimpleAdapter(Context context) {
    inflater = LayoutInflater.from(context);
  }

  @Override public int getCount() {
    return CONTENTS.length;
  }

  @Override public String getItem(int position) {
    return CONTENTS[position];
  }

  @Override public long getItemId(int position) {
    return position;
  }

  @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.simple_list_item, parent, false);
      holder = new ViewHolder(view);
      view.setTag(holder);
    }

    String word = getItem(position);
    holder.word.setText("Word: " + word);
    holder.length.setText("Length: " + word.length());
    holder.position.setText("Position: " + position);
    // Note: don‘t actually do string concatenation like this in an adapter‘s getView.

    return view;
  }

  static class ViewHolder {
    @Bind(R.id.word) TextView word;
    @Bind(R.id.length) TextView length;
    @Bind(R.id.position) TextView position;

    ViewHolder(View view) {
      ButterKnife.bind(this, view);
    }
  }
}

开发版本，没有正式发布的时候，可以再Application中设置：

package com.example.butterknife;

import android.app.Application;
import butterknife.ButterKnife;

public class SimpleApp extends Application {
  @Override public void onCreate() {
    super.onCreate();
    ButterKnife.setDebug(BuildConfig.DEBUG);
  }
}