alertDialog创建登陆界面，判断用户输入

alertDialog创建登陆界面，需要获取用户输入的用户名和密码，获取控件对象的时候不能像主布局文件那样获得，

需要在onClickListener中获取，代码如下：

 public boolean onOptionsItemSelected(MenuItem item) {
         // TODO Auto-generated method stub
         switch(item.getItemId()){
         case 1:
             Intent intent = new Intent();
             intent.setAction(Intent.ACTION_MAIN);
             intent.addCategory(Intent.CATEGORY_HOME);
             startActivity(intent);
             break;
         case 2:
             Toast.makeText(MainActivity.this, "POWER BY BOF", Toast.LENGTH_LONG).show();
             break;
         case 3:
             login();
             break;
         }
         return super.onOptionsItemSelected(item);
     }

     //用户注册
     public void login(){
         /*
          * 此段代码为重点内容
          *
          */
         LayoutInflater factory = LayoutInflater.from(MainActivity.this);
         final View v1 = factory.inflate(R.layout.login, null);
         //创建对话框
         final Builder alertDialog = new AlertDialog.Builder(this);
         alertDialog.setTitle("用户登陆");
         alertDialog.setView(v1);
         alertDialog.setPositiveButton("登录", new DialogInterface.OnClickListener() {

             @Override
             public void onClick(DialogInterface dialog, int which) {
                 /*
                  * 下面两行代码为获取dialog中的控件对象，
                  * 和UI布局获取控件对象略有不同，只能在用到alertDialog的地方进行实现
                  */
                 EditText user = (EditText)v1.findViewById(R.id.user);
                 EditText passwd = (EditText)v1.findViewById(R.id.passwd);
                 String userStr = user.getText().toString();
                 String passwdStr = passwd.getText().toString();
                 if(userStr.equals("android") && passwdStr.equals("asdf123..")){
                     Intent intent1 = new Intent(MainActivity.this,HandproActivity.class);
                     startActivity(intent1);
                 }else{
                     Toast.makeText(MainActivity.this, "账号或密码错误，请重新输入", Toast.LENGTH_LONG).show();
                 }

                 //Toast.makeText(MainActivity.this, "haha", Toast.LENGTH_LONG).show();
             }
         });
         alertDialog.setNegativeButton("去注册", new DialogInterface.OnClickListener() {

             @Override
             public void onClick(DialogInterface dialog, int which) {
                 // TODO Auto-generated method stub

             }
         });
         alertDialog.create().show();
     }