android 上下文菜单详解

<?xml version="1.0" encoding="utf-8"?>

<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
            android:id="@+id/add"
            android:title="添加"
            android:orderInCategory="4"
            />

    <item
            android:id="@+id/delete"
            android:title="删除"
            android:orderInCategory="1"
            />

    <item
            android:id="@+id/query"
            android:title="查询"
            android:orderInCategory="2"
            />

    <item
            android:id="@+id/update"
            android:title="更新"
            android:orderInCategory="3"
            />
</menu>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent"
        >

    <Button
            android:id="@+id/btn"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="弹出上下文菜单"
            />
</LinearLayout>

package com.example.contextMenuTest;

import android.app.Activity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MyActivity extends Activity {
   private Button button;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        button = (Button) findViewById(R.id.btn);

        //为按钮注册contextMenu，当你长按按钮的时候就会调用onCreateContextMenu方法
        registerForContextMenu(button);
    }

    /**
     * 注意：每次长按注册了contextMenu的控件，都会重新调用该方法
     */
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
        System.out.println("com.example.contextMenuTest.MyActivity.onCreateContextMenu");
        getMenuInflater().inflate(R.menu.basic_main, menu);
        //设置标题栏的图标
        menu.setHeaderIcon(R.drawable.ic_launcher);
        //设置标题栏的文字
        menu.setHeaderTitle("请选择操作");
    }

    @Override
    public boolean onContextItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.add:
                Toast.makeText(this, "你点击了添加！", 1).show();
                break;
            case R.id.delete:
                Toast.makeText(this, "你点击了删除！", 1).show();
                break;
            case R.id.update:
                Toast.makeText(this, "你点击了修改！", 1).show();
                break;
            case R.id.query:
                Toast.makeText(this, "你点击了查询！", 1).show();
                break;
        }
        return true;
    }
}