Android 值得记录的几个点

• 通过Drawable的方式改变shap背景颜色

// 以 shap 作为背景，改变 shap 的背景颜色  
TextView test = (TextView) findViewById(R.id.tv_test);  
  
GradientDrawable drawable = (GradientDrawable) test.getBackground();  
drawable.setColor(Color.GREEN);  
drawable.setAlpha(120);  
test.setBackgroundDrawable(drawable);  

• 设置状态栏的高度

int statusBarHeight = mContext.getResources().getDimensionPixelSize
                  (mContext.getResources().getIdentifier("status_bar_height", "dimen", "android"));  
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams
                  (ViewGroup.LayoutParams.MATCH_PARENT, statusBarHeight);  
mTitleTop.setLayoutParams(params); 

• RecyclerView 屏蔽滑动
  解决ScrollView嵌套RecyclerView获得焦点问题

LinearLayoutManager mLayoutManager = new LinearLayoutManager(mContext) {  
       @Override  
       public boolean canScrollVertically() {  
           return false;  
      }  
}; 

• 屏蔽listview的焦点

listview.setFocusable(false);  

• 获得自定义View宽高

    /** 
     * 获取到布局文件的高度和宽度 
     * 
     * @param child 
     */  
    private void measureView(View child) {  
        ViewGroup.LayoutParams lp = child.getLayoutParams();  
        if (lp == null) {  
            lp = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);  
        }  
        int childMeasureWidth = ViewGroup.getChildMeasureSpec(0, 0, lp.width);  
        int childMeasureHeight;  
        if (lp.height > 0) {  
            childMeasureHeight = View.MeasureSpec.makeMeasureSpec(lp.height, View.MeasureSpec.EXACTLY);  
        } else {  
            childMeasureHeight = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);  
        }  
        child.measure(childMeasureWidth, childMeasureHeight);  
    }  

应用

设置 view  measureView(自定义view);  
高  childView.getMeasuredHeight()  
宽  childView.getMeasuredWidth() 

• 反射得到资源

    /**   
     * 反射得到资源id   
     *    
     * @param context   
     * @param key   
     *            传入参数,如"R.drawable.ic_launcher", "R.id.textview"   
     * @return   
     */    
    public static int getResourceId(Context context, String key) {    
        String[] keys = key.split("\\.");    
        Resources res = context.getResources();    
        return res.getIdentifier(keys[2], keys[1], context.getPackageName());    
    }  

• 判断多次点击

private static long lastClickTime = 0;    
    private static final long DIFF = 800;    
    
    /**   
     * 判断两次点击的间隔，如果小于diff，则认为是多次无效点击   
     *   
     * @return   
     */    
    public boolean isFastDoubleClick() {    
        long time = System.currentTimeMillis();    
        long timeD = time - lastClickTime;    
        lastClickTime = time;    
        if (timeD < DIFF) {    
            return true;    
        }    
        return false;    
    }

• FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS:
  如果调出的Activtivity只是一个功能片段，并没有实际的意义，也没有必要出现在长按Home键调出最近使用过的程序类表中，那么使用FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS

Intent intent = new Intent(this, WaitingFallBackDialog.class); 
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS); 
startActivity(intent);