对话框的三个按钮的显示方法实现

Log.d(getClass().toString(),"initDevice is start!!!");
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle("工学1号馆");
builder.setIcon(R.drawable.ic_launcher);
builder.setMessage("浏览wuyudong的博客?");
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
builder.setNeutralButton("扫描", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {

}
});
AlertDialog dialog = builder.create();
dialog.show();