Activity中获取view的高度和宽度为0的原因以及解决方案

原文链接：http://blog.csdn.net/nailsoul/article/details/25909313

在activity中可以调用View.getWidth、View.getHeight()、View.getMeasuredWidth() 、View.getgetMeasuredHeight()来获得某个view的宽度或高度，但是在onCreate()、onStrart()、onResume()方法中会返回0，这是应为当前activity所代表的界面还没显示出来没有添加到WindowPhone的DecorView上或要获取的view没有被添加到DecorView上或者该View的visibility属性为gone 或者该view的width或height真的为0 
所以只有上述条件都不成立时才能得到非0的width和height  

所以要想获取到的width和height为真实有效的 则有以下方法

1.在该View的事件回调里使用  这时候该view已经被显示即被添加到DecorView上  如点击事件  触摸事件   焦点事件等

[java] view
plain copy

View view=findViewById(R.id.tv);  

    view.setOnClickListener(new OnClickListener() {  

          

        @Override  

        public void onClick(View v) {  

            int width = v.getWidth();  

        }  

    });  

2.在activity被显示出来时即添加到了DecorView上时获取宽和高如onWindowFocusChanged() 回调方法

[java] view
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@Override  

  public void onWindowFocusChanged(boolean hasFocus) {  

    View iv1 = findViewById(R.id.iv1);  

View iv2=findViewById(R.id.iv2);  

String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+"  measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();  

String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+"  measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();  

i("onWindowFocusChanged() "+msg1);  

i("onWindowFocusChanged() "+msg2);  

    super.onWindowFocusChanged(hasFocus);  

  }  

3.或在onResume方法最后开线程300毫秒左右后获取宽和高   因为onResume执行完后300毫秒后 界面就显示出来了  

当然地2种和地3种方法要保证获取宽高的view是在setContentView时设进去的View或它的子View

[java] view
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view.postDelayed(new Runnable() {  

              

            @Override  

            public void run() {  

                View iv1 = findViewById(R.id.iv1);  

                View iv2=findViewById(R.id.iv2);  

                String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+"  measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();  

                String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+"  measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();  

                i("onWindowFocusChanged() "+msg1);  

                i("onWindowFocusChanged() "+msg2);  

            }  

        }, 300);  

4.在onCreate()或onResume()等方法中需要获取宽高时使用getViewTreeObserver().addOnGlobalLayoutListener()来添为view加回调在回调里获得宽度或者高度获取完后让view删除该回调

[java] view
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view.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {  

          

        @Override  

        public void onGlobalLayout() {  

            view.postDelayed(new Runnable() {  

                  

                @Override  

                public void run() {  

                    View iv1 = findViewById(R.id.iv1);  

                    View iv2=findViewById(R.id.iv2);  

                    String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+"  measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();  

                    String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+"  measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();  

                    i("onWindowFocusChanged() "+msg1);  

                    i("onWindowFocusChanged() "+msg2);  

                }  

            }, 300);  

        }  

    });  

5.在窗口焦点发生变化时获取宽高 onResume完后就会把界面渲染到窗口上 渲染完后将执行窗口焦点花生变化回调   所以onResume到 onWindowFocusChanged为把界面渲染到窗口的时间

[java] view
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boolean measure;  

    View iv1;  

    View iv2;  

    @Override  

    public void onWindowFocusChanged(boolean hasFocus) {  

        super.onWindowFocusChanged(hasFocus);  

        if(hasFocus && !measure){  

            measure=true;  

            measure();  

        }  

    }  

    private void findViews(){  

        iv1 = findViewById(R.id.iv1);  

        iv2 =findViewById(R.id.iv2);  

    }  

    private void measure(){  

        String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+"  measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();  

        String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+"  measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();  

        i("onWindowFocusChanged() "+msg1);  

        i("onWindowFocusChanged() "+msg2);  

    }