MENU 菜单技术详解

package com.yarin.android.MyContacts;


import android.app.ListActivity;
import android.content.ComponentName;
import android.content.ContentUris;
import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;


public class MyContacts extends ListActivity
{
private static final String TAG = "MyContacts";

private static final int AddContact_ID = Menu.FIRST;
private static final int EditContact_ID = Menu.FIRST+1;
private static final int DELEContact_ID = Menu.FIRST+2;
private static final int EXITContact_ID = Menu.FIRST+3;

public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setDefaultKeyMode(DEFAULT_KEYS_SHORTCUT);

        Intent intent = getIntent();
        if (intent.getData() == null) {
        Log.v(TAG, "getdata null ");
            intent.setData(ContactsProvider.CONTENT_URI);
        }


        getListView().setOnCreateContextMenuListener(this);
        getListView().setBackgroundResource(R.drawable.bg);
        Log.v(TAG, "oncreate ");
        Cursor cursor = managedQuery(getIntent().getData(), ContactColumn.PROJECTION, null, null,null);


        //注册每个列表表示形式 ：姓名 + 移动电话
        SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
android.R.layout.simple_list_item_2,
cursor,
new String[] {ContactColumn.NAME, ContactColumn.MOBILENUM },
new int[] { android.R.id.text1, android.R.id.text2 });


        setListAdapter(adapter);
}


    public boolean onCreateOptionsMenu(Menu menu) 
    {
        super.onCreateOptionsMenu(menu);
        Log.v(TAG, "onCreateOptionsMenu");
        //添加联系人
        menu.add(0, AddContact_ID, 0, R.string.add_user)
        .setShortcut('3', 'a')
        .setIcon(R.drawable.add);
        //动态添加菜单技术
        Intent intent = new Intent(null, getIntent().getData());
        intent.addCategory(Intent.CATEGORY_ALTERNATIVE);
        menu.addIntentOptions(Menu.CATEGORY_ALTERNATIVE, 0, 0,
                new ComponentName(this, MyContacts.class), null, intent, 0, null);


        //退出程序
        menu.add(0, EXITContact_ID, 0, R.string.exit)
    .setShortcut('4', 'd')
    .setIcon(R.drawable.exit);
        return true;
        
    }
    
    //处理菜单操作
    public boolean onOptionsItemSelected(MenuItem item) 
    {
        switch (item.getItemId()) 
        {
        case AddContact_ID:
            //添加联系人
            startActivity(new Intent(Intent.ACTION_INSERT, getIntent().getData()));
            return true;
        case EXITContact_ID:
        //退出程序
        this.finish();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
    
    public boolean onPrepareOptionsMenu(Menu menu)
{
super.onPrepareOptionsMenu(menu);
final boolean haveItems = getListAdapter().getCount() > 0;
        Log.v(TAG, "onPrepareOptionsMenu");
if (haveItems)
{

Uri uri = ContentUris.withAppendedId(getIntent().getData(), getSelectedItemId());
Log.v(TAG, uri.toString());
Intent[] specifics = new Intent[2];
specifics[0] = new Intent(Intent.ACTION_EDIT, uri);
specifics[1] = new Intent(Intent.ACTION_VIEW, uri);
MenuItem[] items = new MenuItem[2];

//添加满足条件的菜单，当按下菜单之后，intent的是specifics[0] 和 specifics[1]要启动的activity
Intent intent = new Intent(null, uri);
intent.addCategory(Intent.CATEGORY_ALTERNATIVE);
menu.addIntentOptions(Menu.CATEGORY_ALTERNATIVE, 0, 0, null, specifics, intent, 0, items);


if (items[0] != null)
{
//编辑联系人
items[0].setShortcut('1', 'e').setIcon(R.drawable.edituser).setTitle(R.string.editor_user);   
}
if (items[1] != null)
{
//查看联系人
items[1].setShortcut('2', 'f').setTitle(R.string.view_user).setIcon(R.drawable.viewuser);   
}
}
else
{//没有项目即去掉添加的菜单
menu.removeGroup(Menu.CATEGORY_ALTERNATIVE);
}
return true;
}
    //动态菜单处理
    //点击的默认操作也可以在这里处理
    protected void onListItemClick(ListView l, View v, int position, long id)   
    {   
        Uri uri = ContentUris.withAppendedId(getIntent().getData(), id);   
  
        String action = getIntent().getAction();   
        if ( Intent.ACTION_EDIT.equals(action) )
{
        //编辑联系人
        startActivity(new Intent(Intent.ACTION_EDIT, uri));  
}  
        else
        {     
        //查看联系人
        startActivity(new Intent(Intent.ACTION_VIEW, uri));       
        }  
    }   
    
    //长按界面触发的菜单
public void onCreateContextMenu(ContextMenu menu, View view, ContextMenuInfo menuInfo)
{
AdapterView.AdapterContextMenuInfo info;
try
{
info = (AdapterView.AdapterContextMenuInfo) menuInfo;
}
catch (ClassCastException e)
{
return;
}
//得到长按的数据项
Cursor cursor = (Cursor) getListAdapter().getItem(info.position);
if (cursor == null)
{
return;
}
        //设置上下文菜单的标题为日志标题
menu.setHeaderTitle(cursor.getString(1));
//添加删除菜单
menu.add(0, DELEContact_ID, 0, R.string.delete_user);
}
    
//  对于上下文菜单项选中的事件处理，是通过重载onContextItemSelected实现的。
@Override
    public boolean onContextItemSelected(MenuItem item)
{
AdapterView.AdapterContextMenuInfo info;
try
{
info = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
}
catch (ClassCastException e)
{
return false;
}


switch (item.getItemId())
{
case DELEContact_ID:
{
//删除一条记录
Uri noteUri = ContentUris.withAppendedId(getIntent().getData(), info.id);
getContentResolver().delete(noteUri, null, null);
return true;
}
}
return false;
}
}