android 菜单的运用

android 菜单的使用
Options Menu  当用户按下menu button按钮时显示的菜单
Context Menu  当用户长久按住屏幕，被注册显示上下文菜单的视图时显示的菜单
Submenu       当用户按下一个菜单的某个选项时弹出的子菜单




以上三种菜单也就是我们经常所说的：选项菜单，上下文菜单和子菜单。




一.上下文菜单





       1，实现onCreateContextMenu即可创建该菜单



               示例：@Override
                     public void onCreateContextMenu(ContextMenu menu, View v,
                               ContextMenuInfo menuInfo) {
                              // TODO Auto-generated method stub

                              //加载已定义好的布局menu.xml
                              MenuInflater inflater = getMenuInflater();
                              inflater.inflate(R.layout.menu, menu);

                              //或者用代码来实现菜单添加

                                 --menu.setHeaderTitle("长按菜单-ContextMenu");  
                       -- menu.add(0, 0, 0, "弹出长按菜单0");
                     -- menu.add(0, 1, 0, "弹出长按菜单1");  

                             super.onCreateContextMenu(menu, v, menuInfo);
                             }



        2.当菜单某个选项被点击时调用该方法


                         @Override
                          public boolean onContextItemSelected(MenuItem item) {
                            // TODO Auto-generated method stub
                              AdapterContextMenuInfo infor = (AdapterContextMenuInfo)item.getMenuInfo();
                             switch(item.getItemId())
                               {
                                  case R.id.help:
                                 .......

                                  return true;
                                  case R.id.addnew:
                                  ........

                                   return true;

                                   ......

                                 }

                                }



           3.当上下文菜单关闭时调用的方法



                        @Override
                        public void onContextMenuClosed(Menu menu) {
                        // TODO Auto-generated method stub
                        super.onContextMenuClosed(menu);
                          }







对于这样已经定义好的上下文菜单，总得注册到一些控件上，这样等我们长按住这个控件时，


才能跳出上下文菜单。那该怎么把上下文菜单注册到某些控件上呢，大难很简单


：registerForContextMenu(this.listView1)；这里是注册到一个ListView上了，这样长按


ListView就能跳出上下文菜单了。



二，选项菜单


       相比而言就简单了


       一样道理只需实现onCreateoptionsMenu，onOptionsItemSelected和o


nOptionsMenuClosed就ok了



三，子菜单


      按理说子菜单也不难，确实如此，当实现了选项菜单，或上下文菜单（在上下文菜单里也


可以实现子菜单，这里我们就举这样的例子），则子菜单的实现便是水到渠成。如上面的代


码：


                    @Override
                     public void onCreateContextMenu(ContextMenu menu, View v,
                               ContextMenuInfo menuInfo) {
                              // TODO Auto-generated method stub

                              //加载已定义好的布局menu.xml
                              MenuInflater inflater = getMenuInflater();
                              inflater.inflate(R.layout.menu, menu);

                              //或者用代码来实现菜单添加

                                 --menu.setHeaderTitle("长按菜单-ContextMenu");  
                                 -- menu.add(0, 0, 0, "弹出长按菜单0");
                                 -- menu.add(0, 1, 0, "弹出长按菜单1");  
                              //在这里就可以添加实现子菜单的代码

                                int base = menu.FIRST + 100;

                                SubMenu sm = menu.addSubMenu(base, base + 1, Menu.NONE, "submenu");
                                 sm.add(base, base + 2, base + 2, "sub item1");
                                sm.add(base, base + 3, base + 3, "sub item2");
                             super.onCreateContextMenu(menu, v, menuInfo);
                             }



这样子菜单便也实现了，对于它的单击事件，只要在相应的选项菜单或者上下文菜单的侦听器


里照样判断执行就OK了。