Android開發動態獲取控件寬高

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最近做項目自定義控件時候想獲取控件中元素參數，但各種失敗，網上搜了下，自己也總結一下。

package com.example.androidtest_02;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewTreeObserver;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.WindowManager.LayoutParams;
import android.widget.Button;
import android.widget.TextView;

/**
 *
 * 這個activity測試 ： 1.Activity的生命週期 2.程序動態獲取控件的寬高
 *
 * 結論：activity啓動時候：onCreate()-->onStart()--->onResum()-->onAttachedToWindow()-->
 * onWindowFocusChanged()
 *
 * 當另外一個activity be in front of
 * 的時候：onPause()--->onWindowFocusChanged()-->onStop()
 *
 * 當第一個activity恢復到最前面時候：onRestart()--->onStart()--->onResum()--->
 * onWindowFocusChanged()
 *
 * 當activityfinish的時候：onPause()-->onWindowFocusChanged()-->onStop()-->onDestroy(
 * )
 *
 *
 * onAttachedToWindow()此時打印出了控件寬高，其他地方的打印爲0 ，so,activity全面加載完了之後纔會獲取到控件的寬高，
 * 當我們需要獲取控件的寬高時，需要等activity加載完。
 *
 * 第二種與第三種方式：即使實在oncreate()方法裏面聲明瞭，回調裏面的內容也只能在onResume()方法被調用後才能得到執行。
 */
public class MainActivity extends Activity implements OnClickListener {

    public void printLog(String s) {

        Log.e("-------------------------------", s);
    }

    Button btn1;
    Button btn2;
    TextView textview1;

    /**
     * 第一種獲取寬高的方式。
     */
    int w = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
    int h = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn1 = (Button) findViewById(R.id.btn1);
        btn1.setOnClickListener(this);
        btn2 = (Button) findViewById(R.id.btn2);
        textview1 = (TextView) findViewById(R.id.textview1);

        textview1.measure(w, h);
        // int height =textview1.getMeasuredHeight();
        // int width =textview1.getMeasuredWidth();
        printLog("直接獲取寬高：width:" + textview1.getWidth() + "---->height:"
                + textview1.getHeight());
        printLog("使用mesure()獲取寬高：width:" + textview1.getWidth()
                + "---->height:" + textview1.getHeight());

        // 即使實在oncreate()方法裏面聲明瞭，回調裏面的內容也只能在onResume()方法被調用後才能得到執行。

        // 第二種獲取寬高的方式
        ViewTreeObserver viewTreeObserver = textview1.getViewTreeObserver();
        viewTreeObserver
                .addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {

                    @Override
                    public boolean onPreDraw() {

                        printLog("使用ViewTreeObserver 獲取寬高：width:"
                                + textview1.getMeasuredWidth() + "---->height:"
                                + textview1.getMeasuredHeight());

                        return true;
                    }
                });

        // 第三種獲取寬高的方式
        ViewTreeObserver vtb1 = textview1.getViewTreeObserver();
        vtb1.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {

            @Override
            public void onGlobalLayout() {
                textview1.getViewTreeObserver().addOnGlobalLayoutListener(this);
                printLog("使用OnGlobalLayoutListener 獲取寬高：width:"
                        + textview1.getWidth() + "---->height:"
                        + textview1.getHeight());
            }
        });

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    @Override
    protected void onStart() {
        super.onStart();
        printLog("onstart()");
        printLog("width:" + textview1.getWidth() + "---->height:"
                + textview1.getHeight());

    }

    @Override
    protected void onResume() {
        super.onResume();
        printLog("onResume()");
        printLog("width:" + textview1.getWidth() + "---->height:"
                + textview1.getHeight());
    }

    @Override
    public void onAttachedToWindow() {
        super.onAttachedToWindow();
        printLog("onAttachedToWindow()");
        printLog("width:" + textview1.getWidth() + "---->height:"
                + textview1.getHeight());
    }

    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        printLog("onWindowFocusChanged()");
        printLog("width:" + textview1.getWidth() + "---->height:"
                + textview1.getHeight());// 此時打印出了控件寬高，其他地方的打印爲0
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        printLog("onRestart()");
    }

    @Override
    public void onWindowAttributesChanged(LayoutParams params) {
        super.onWindowAttributesChanged(params);
        printLog("onWindowAttributesChanged()");
    }

    @Override
    protected void onPause() {
        super.onPause();
        printLog("onPause()");
    }

    @Override
    protected void onStop() {
        super.onStop();
        printLog("onStop()");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        printLog("onDestroy()");
    }

    @Override
    public void onClick(View v) {

        if (v.equals(btn1)) {
            printLog("+++++++++++++++++++馬上要跳轉了++++++++++++++++++");
            Intent intent = new Intent(MainActivity.this, Activity1.class);
            startActivity(intent);
        } else if (v.equals(btn2)) {

            printLog("+++++++++++++++++++馬上finish了++++++++++++++++++");
            this.finish();
        }
    }

    @Override
    public void onBackPressed() {

        printLog("+++++++++++++++++++我點了返回鍵，馬上要跳轉了++++++++++++++++++");

    }

}