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();
    }