ContextMenu

OnCreateContextMenu也是创建菜单，但此菜单是通过点击其他控件创建的，而不是通过点"Menu"按钮创建的。另外OnCreateContextMenu创建菜单后会使后台失去焦点，而通过点击Menu按钮创建的菜单（调用onCreateOptionsMenu方法）不会使后台失去焦点。
代码：

package com.kevin.contextmenu;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.View.OnCreateContextMenuListener;
import android.widget.ImageView;
import android.widget.TextView;

public class Main extends Activity {
	private static final int CONTEXT_ITEM1 = Menu.FIRST;
	private static final int CONTEXT_ITEM2 = Menu.FIRST + 1;
	private static final int CONTEXT_ITEM3 = Menu.FIRST + 2;
	private TextView tv_title;
	// 重写OnContextItemSelected来定义用户单击menu后的动作
	@Override
	public boolean onContextItemSelected(MenuItem item) {
		// 创建Bitmap对象
		Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.kobe);
		int height = bitmap.getHeight();
		int width = bitmap.getWidth();
		try{
			switch (item.getItemId()) {
			case CONTEXT_ITEM1:
				tv_title.setText(getString(R.string.height) + String.valueOf(height));
				break;
			case CONTEXT_ITEM2:
				tv_title.setText(getString(R.string.width) + String.valueOf(width));
				break;
			case CONTEXT_ITEM3:
				tv_title.setText(getString(R.string.handw) + String.valueOf(height) + ", " + String.valueOf(width));
				break;
			default:
				break;
			}
		}catch (Exception e) {
			e.printStackTrace();
		}
		return super.onContextItemSelected(item);
	}
	private ImageView img;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        tv_title = (TextView) findViewById(R.id.tv_title);
        img = (ImageView) findViewById(R.id.imageView1);
        img.setImageDrawable(getResources().getDrawable(R.drawable.kobe));
        // 设置OnCreateContextMenu来创建ContextMenu选项，       
        //  在ImageView上可以使用ContextMenu(长按住Imageview就会跳出来菜单)
        // 它与onCreateOptionsMenu区别在于，它会使后台失去焦点
        img.setOnCreateContextMenuListener(new OnCreateContextMenuListener() {

			@Override
			public void onCreateContextMenu(ContextMenu menu, View v,
					ContextMenuInfo menuInfo) {
				menu.add(Menu.NONE, CONTEXT_ITEM1, 0, R.string.getheight);
				menu.add(Menu.NONE, CONTEXT_ITEM2, 0, R.string.getwidth);
				menu.add(Menu.NONE, CONTEXT_ITEM3, 0, R.string.getheightandwidth);				
			}
		});
    }
}