ButterKnife 的简易替代品，不为findViewById折腰

为什么要造轮子

自己平常写代码一直用ButterKnife，功能太强大了有木有！但是最近有个需要在匿名内部类中去findView的时候却发现ButterKnife好像不支持在匿名内部类中进行find，（我也不确定支不支持，反正没找到相应的方法）编译后没有生成相应的ViewBinder类，应该是编译时故意忽略了匿名内部类吧。所以此时也很无奈啊。。。只能自己动手丰衣足食了。

内容为原创，希望能给需要的人帮助，不喜勿喷

一、思路

将需要查找的View包装成WrapView对象放到查找队列中，指定View的类型和id，在容器（activity，fragment等）初始化完View以后再调用ViewFinder的findFrom方法进行查找。
需要使用View时调用WrapView的get()方法将View取出。

使用起来确实稍微有点麻烦。。。不过作为强迫症患者，这样的代码↓↓↓能把我逼疯

public class MainActivity extends Activity{
    private TextView nameTv;
    private TextView ageTv;
    private TextView sexTv;
    private TextView nationTv;
    private TextView addressTv;
    private Button confirmBtn;
    private Button cancelBtn;
    private Button closeBtn;
    private LinearLayout mainLayout;
    private LinearLayout loadingLayout;
    private LinearLayout errorLayout;
    
    onCreate(){
        supper.onCreate();
        setConentView(R.layout.activity_main);
        findViews();
        initView();
    }

    public void findViews(){
        nameTv = (TextView) findViewById(R.id.tv_name);
        ageTv= (TextView) findViewById(R.id.tv_age);
        sexTv= (TextView) findViewById(R.id.tv_sex);
        nationTv = (TextView) findViewById(R.id.tv_nation);
        addressTv= (TextView) findViewById(R.id.tv_address);
        confirmBtn = (Button) findViewById(R.id.btn_confirm);
        cancelBtn= (Button) findViewById(R.id.btn_cancel);
        closeBtn = (Button) findViewById(R.id.btn_close);
        mainLayout= (LinearLayout) findViewById(R.id.layout_main);
        loadingLayout= (LinearLayout) findViewById(R.id.layout_loading);
        errorLayout= (LinearLayout) findViewById(R.id.layout_error);
    }

    public void initView(){
        nameTv.setText("张三");    
        ageTv.setText("26");      
        sexTv.setText("男");     
        ...
    }
    ...

}

经过改进后的代码是这样的

public class MainActivity extends Activity{

    private ViewFinder finder = new ViewFinder();
    private WrapView<TextView> nameTv= finder.apply(R.id.tv_name);
    private WrapView<TextView> ageTv= finder.apply(R.id.tv_age);
    private WrapView<TextView> sexTv= finder.apply(R.id.tv_sex);
    private WrapView<TextView> nationTv= finder.apply(R.id.tv_nation);
    private WrapView<TextView> addressTv= finder.apply(R.id.tv_address);
    private WrapView<Button> confirmBtn= finder.apply(R.id.btn_confirm);
    private WrapView<Button> cancelBtn= finder.apply(R.id.btn_cancel);
    private WrapView<Button> closeBtn= finder.apply(R.id.btn_close);
    private WrapView<LinearLayout > mainLayout= finder.apply(R.id.layout_main);
    private WrapView<LinearLayout > loadingLayout= finder.apply(R.id.layout_loading);
    private WrapView<LinearLayout > errorLayout= finder.apply(R.id.layout_error);
    
    onCreate(){
        supper.onCreate();
        setConentView(R.layout.activity_main);
        finder.findFrom(this);
        initView();
    }

    public void initView(){
        nameTv.get().setText("张三");    
        ageTv.get()..setText("26");      
        sexTv.get()..setText("男");   
        confirmBtn.get().setOnclickListener(this);  
        ...
    }
    ...

}

二、WrapView 和 ViewFinder的代码

WrapView

/**
 * Wapper class to maintain View.
 * Created by Leo on 2018/2/12.
 */
public class WrapView<T extends View> {
    private T view;
    @IdRes
    private int id;

    WrapView(@IdRes int id) {
        this.id = id;
    }

    public T get() {
        return view;
    }

    void setView(T view) {
        this.view = view;
    }

    void find(View from) {
        if (from == null) throw new NullPointerException("find view from a null object.");
        view = (T) from.findViewById(id);
        if (view == null) throw new ViewNotFoundException("View not found for id : " + id);
    }

    void find(Activity from) {
        if (from == null) throw new NullPointerException("find view from a null object.");
        view = (T) from.findViewById(id);
        if (view == null) throw new ViewNotFoundException("View not found for id : " + id);
    }
}

ViewFinder

/**
 * Helper class to maintain finding tasks.
 * Created by Leo on 2018/2/12.
 */
public class ViewFinder {
    private HashMap<Integer, WrapView<?>> views = new HashMap<>();

    public <T extends View> WrapView<T> apply(@IdRes int id){
        WrapView<T> wrapper = (WrapView<T>) views.get(id);
        if (wrapper == null){
            wrapper = new WrapView<>(id);
            views.put(id,wrapper);
        }
        return wrapper;
    }

    public void findFrom(View from) {
        Collection<WrapView<?>> wrapViews = views.values();
        for (WrapView<?> wrapView : wrapViews) {
            wrapView.find(from);
        }
    }

    public void findFrom(Activity from) {
        Collection<WrapView<?>> wrapViews = views.values();
        for (WrapView<?> wrapView : wrapViews) {
            wrapView.find(from);
        }
    }
}

代码量很少，需要的童鞋可以直接拿去用，祝大家新年快乐！