一个 BaseActivity 封装小技巧

1. 使用

• 通过 ViewHolder 操作所有 View, 再也不用写几十行控件变量了
• ViewHolder 提供常用控件方法链式调用
• 没有在 BaseActivity 中写 initView() 之类的函数, 尽可能不入侵代码

public class TestActivity extends BaseActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.test_layout);
        holder.setText(R.id.button, "Test")
              .setText(R.id.name_tv, "Name");
    }
}

2. BaseActivity

public class BaseActivity extends AppCompatActivity {

    protected ViewHolder holder;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 去除默认背景, 防止过渡绘制
        getWindow().setBackgroundDrawable(null);
    }

    @Override
    public void setContentView(View view) {
        super.setContentView(view);
        holder = new ViewHolder(getApplicationContext(), getWindow().getDecorView());
    }

    @Override
    public void setContentView(int layoutResID) {
        super.setContentView(layoutResID);
        holder = new ViewHolder(getApplicationContext(), getWindow().getDecorView());
    }

    @Override
    public void setContentView(View view, ViewGroup.LayoutParams params) {
        super.setContentView(view, params);
        holder = new ViewHolder(getApplicationContext(), getWindow().getDecorView());
    }
}

public class ViewHolder extends RecyclerView.ViewHolder {

    private final Context context;
    private final SparseArray<View> mSparseArray;


    public ViewHolder(Context context, @NonNull View itemView) {
        super(itemView);
        this.context = context;
        mSparseArray = new SparseArray<>();

    }

    @SuppressWarnings("unchecked")
    public final <T extends View> T getView(@IdRes int viewId) {
        View view = mSparseArray.get(viewId);
        if (view == null) {
            view = itemView.findViewById(viewId);     // 使用 RecyclerView.ViewHolder 保存的 itemView
            mSparseArray.put(viewId, view);
        }
        return (T) view;
    }


    /********************************** 常用函数 ****************************************/

    public ViewHolder setVisibility(int viewId, int visibility) {
        View view = getView(viewId);
        view.setVisibility(visibility);
        return this;
    }

    public ViewHolder setPadding(int viewId, int left, int top, int right, int bottom) {
        View view = getView(viewId);
        view.setPadding(left, top, right, bottom);
        return this;
    }

    public ViewHolder setSelected(int viewId, boolean selected) {
        View view = getView(viewId);
        view.setSelected(selected);
        return this;
    }

    public ViewHolder setBackgroundColor(int viewId, @ColorInt int color) {
        View view = getView(viewId);
        view.setBackgroundColor(color);
        return this;
    }

    public ViewHolder setBackgroundRes(int viewId, @DrawableRes int resId) {
        View view = getView(viewId);
        view.setBackgroundResource(resId);
        return this;
    }

    public ViewHolder setBackgroundDrawable(int viewId, Drawable drawable) {
        View view = getView(viewId);
        view.setBackground(drawable);
        return this;
    }

    public ViewHolder setBackgroundBitmap(int viewId, Bitmap bitmap) {
        View view = getView(viewId);
        view.setBackground(new BitmapDrawable(context.getResources(), bitmap));
        return this;
    }

    public ViewHolder setEnabled(int viewId, boolean enabled) {
        View view = getView(viewId);
        view.setEnabled(enabled);
        return this;
    }

    public boolean isEnabled(int viewId) {
        return getView(viewId).isEnabled();
    }



    /********************************** 常用监听 ****************************************/

    public ViewHolder setOnClickListener(int viewId, View.OnClickListener listener) {
        View view = getView(viewId);
        view.setOnClickListener(listener);
        return this;
    }

    public ViewHolder setOnTouchListener(int viewId, View.OnTouchListener listener) {
        View view = getView(viewId);
        view.setOnTouchListener(listener);
        return this;
    }

    public ViewHolder setOnLongClickListener(int viewId, View.OnLongClickListener listener) {
        View view = getView(viewId);
        view.setOnLongClickListener(listener);
        return this;
    }

    /**
     * 设置 RecyclerView item 点击监听
     * @param listener
     * @return
     */
    public ViewHolder setOnItemClickListener(View.OnClickListener listener) {
        itemView.setClickable(true);
        itemView.setOnClickListener(listener);
        return this;
    }

    /**
     * 设置 RecyclerView item 长按监听
     * @param listener
     * @return
     */
    public ViewHolder onItenLongClickListener(View.OnLongClickListener listener) {
        itemView.setLongClickable(true);
        itemView.setOnLongClickListener(listener);
        return this;
    }



    /********************************** TextView 相关函数 ****************************************/

    public ViewHolder setText(int viewId, CharSequence value) {
        TextView view = getView(viewId);
        view.setText(value);
        return this;
    }

    public ViewHolder setTextSize(int viewId, int testSize) {
        TextView view = getView(viewId);
        view.setTextSize(testSize);
        return this;
    }

    public ViewHolder setTextColor(int viewId, @ColorInt int textColor) {
        TextView view = getView(viewId);
        view.setTextColor(textColor);
        return this;
    }

    public ViewHolder setTextColorRes(int viewId, @ColorRes int color) {
        TextView view = getView(viewId);
        view.setTextColor(context.getResources().getColor(color));
        return this;
    }

    public ViewHolder setTextDrawable(int viewId, Drawable left, Drawable top, Drawable right, Drawable bottom) {
        TextView textView = getView(viewId);
        textView.setCompoundDrawablesWithIntrinsicBounds(left, top, right, bottom);
        return this;
    }

    public ViewHolder addTextChangedListener(int viewId, TextWatcher watcher) {
        EditText editText = getView(viewId);
        editText.addTextChangedListener(watcher);
        return this;
    }



    /********************************** CheckBox 相关函数 ****************************************/

    public ViewHolder setOnCheckedChangeListener(int viewId, final CheckBox.OnCheckedChangeListener listener) {
        CheckBox checkBox = getView(viewId);
        checkBox.setOnCheckedChangeListener(listener);
        return this;
    }

    public ViewHolder setChecked(int viewId, boolean checked) {
        Checkable view = getView(viewId);
        view.setChecked(checked);
        return this;
    }

    public boolean isChecked(int viewId) {
        CheckBox checkBox = getView(viewId);
        return checkBox.isChecked();
    }



    /********************************** ProgressBar 相关函数 ****************************************/

    public ViewHolder setMax(int viewId, int max) {
        ProgressBar view = getView(viewId);
        view.setMax(max);
        return this;
    }

    public ViewHolder setPressed(int viewId, boolean pressed) {
        View view = getView(viewId);
        view.setPressed(pressed);
        return this;
    }



    /********************************** ImageView 相关函数 *****************************************/

    public ViewHolder setImageResource(int viewId, int imageResId) {
        ImageView view = getView(viewId);
        view.setImageResource(imageResId);
        return this;
    }

    public ViewHolder setImageDrawable(int viewId, Drawable drawable) {
        ImageView view = getView(viewId);
        view.setImageDrawable(drawable);
        return this;
    }

    public ViewHolder setImageBitmap(int viewId, Bitmap bitmap) {
        ImageView view = getView(viewId);
        view.setImageBitmap(bitmap);
        return this;
    }
}