Activity启动过程中获取组件宽高的五种方式

第一种:(重写Activity的onWindowFocusChanged方法)

/**
 * 重写Acitivty的onWindowFocusChanged方法
 */ 
@Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
/**
 * 当hasFocus为true的时候，说明Activity的Window对象已经获取焦点，进而Activity界面已经加载绘制完成
 */
if (hasFocus) {
int widht = titleText.getWidth();
int height = titleText.getHeight();
Log.i(TAG, "onWindowFocusChanged width:" + widht + "   "
+ "  height:" + height;
}
}

第二种:(为组件添加OnGlobalLayoutListener事件监听)

/**
 * 为Activity的布局文件添加OnGlobalLayoutListener事件监听，当回调到onGlobalLayout方法的时候我们通过getMeasureHeight和getMeasuredWidth方法可以获取到组件的宽和高
 */
private void initOnLayoutListener() {
final ViewTreeObserver viewTreeObserver = this.getWindow().getDecorView().getViewTreeObserver();
viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
Log.i(TAG, "开始执行onGlobalLayout().........");
int height = titleText.getMeasuredHeight();
int width = titleText.getMeasuredWidth();

Log.i(TAG, "height:" + height + "   width:" + width);
   // 移除GlobalLayoutListener监听 
   MainActivity.this.getWindow().getDecorView().getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
});
}

第三种:(为组件添加OnPreDrawListener事件监听)

/**
 * 初始化viewTreeObserver事件监听,重写OnPreDrawListener获取组件高度
 */
private void initOnPreDrawListener() {
final ViewTreeObserver viewTreeObserver = this.getWindow().getDecorView().getViewTreeObserver();
viewTreeObserver.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
Log.i(TAG, "开始执行onPreDraw().........");
int height = titleText.getMeasuredHeight();
int width = titleText.getMeasuredWidth();

Log.i(TAG, "height:" + height + "   width:" + width);
// 移除OnPreDrawListener事件监听
MainActivity.this.getWindow().getDecorView().getViewTreeObserver().removeOnPreDrawListener(this);
return true;
}
});
}

第四种:(使用View.post方法获取组件的宽高)

/**
 * 使用View的post方法获取组件的宽度和高度
 */
private void initViewHandler() {
titleText.post(new Runnable() {
@Override
public void run() {
int width = titleText.getWidth();
int height = titleText.getHeight();

Log.i(TAG, "initViewHandler height:" + height + "  width:" + width);
}
});
}

第五种:(通过Handler对象使用异步消息获取组件的宽高)

/**
 * 在onCreate方法中发送异步消息，在handleMessage中获取组件的宽高
 */
private Handler mHandler = new Handler() {

@Override
public void handleMessage(Message msg) {
if (msg.what == 101) {
int width = titleText.getWidth();
int height = titleText.getHeight();

Log.i(TAG, "initViewHandler height:" + height + "  width:" + width);
}
}
};