Android编程动态创建视图View的方法

在Android开发中，在Activity中关联视图View是一般使用setContentView方法，该方法一种参数是使用XML资源直接创建：setContentView (int layoutResID)，指定layout中的一个XML的ID即可，这种方法简单。另一个方法是setContentView(android.view.View)，参数是指定一个视图View对象，这种方法可以使用自定义的视图类。

在一些场合中，需要对View进行一些定制处理，比如获取到Canvas进行图像绘制，需要重载View::onDraw方法，这时需要对View进行派生一个类，重载所需要的方法，然后使用setContentView(android.view.View)与Activity进行关联，具体代码举例如下：

public class temp extends Activity { /** 在Activity中关联视图view */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new DrawView(this)); } /*自定义类*/ private class DrawView extends View { private Paint paint; /** * Constructor */ public DrawView(Context context) { super(context); paint = new Paint(); // set's the paint's colour paint.setColor(Color.GREEN); // set's paint's text size paint.setTextSize(25); // smooth's out the edges of what is being drawn paint.setAntiAlias(true); } protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.drawText("Hello World", 5, 30, paint); // if the view is visible onDraw will be called at some point in the // future invalidate(); } } }

第二个例子，动态绘图

public class MyAndroidProjectActivity extends Activity { /** Called when the activity is first created. */ /* public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); }*/ static int times = 1; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new DrawView(this)); } private class DrawView extends View { Paint vPaint = new Paint(); private int i = 0; public DrawView(Context context) { super(context); } protected void onDraw(Canvas canvas) { super.onDraw(canvas); System.out.println("this run " + (times++) +" times!"); // 设定绘图样式 vPaint.setColor( 0xff00ffff ); //画笔颜色 vPaint.setAntiAlias( true ); //反锯齿 vPaint.setStyle( Paint.Style.STROKE ); // 绘制一个弧形 canvas.drawArc(new RectF(60, 120, 260, 320), 0, i, true, vPaint ); // 弧形角度 if( (i+=10) > 360 ) i = 0; // 重绘, 再一次执行onDraw 程序 invalidate(); } } }