接上一篇，加入验证用户名是否已经注冊功能！

仅仅须要改动MainActivity.java:

package com.example.logintest;

import java.util.List;

import org.w3c.dom.UserDataHandler;

import cn.bmob.v3.Bmob;

import cn.bmob.v3.BmobQuery;

import cn.bmob.v3.listener.FindListener;

import cn.bmob.v3.listener.SaveListener;

import android.os.Bundle;

import android.app.Activity;

import android.view.Menu;

import android.view.View;

import android.widget.EditText;

import android.widget.Toast;

public class MainActivity extends Activity {

	private EditText mUserName,mPassword;

	@Override

	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_main);

		Bmob.initialize(this, "8f3ffb2658d8a3366a70a0b0ca0b71b2");

		mUserName=(EditText) findViewById(R.id.et_username);

		mPassword=(EditText) findViewById(R.id.et_password);

	}

	public void submit(View view){

		final String username=mUserName.getText().toString();

		final String password=mPassword.getText().toString();

		if(username.equals("")||password.equals("")){

			Toast.makeText(this, "用户名或密码不能为空！", 3).show();

		}else{

			BmobQuery<User> query =new BmobQuery<User>();//查询类

			query.addWhereEqualTo("userName", username);//查询条件

			query.findObjects(MainActivity.this, new FindListener<User>() {

				@Override

				public void onSuccess(List<User> userlist) {

					if(userlist.size()==0){//查询不到，用户名可用

						User user=new User();

						user.setUserName(username);

						user.setUserPassword(password);

						user.save(MainActivity.this,new SaveListener() {

							@Override

							public void onSuccess() {

								Toast.makeText(MainActivity.this, "注冊成功！

", 3).show();

							}

							@Override

							public void onFailure(int arg0, String arg1) {

								Toast.makeText(MainActivity.this, "注冊失败！", 3).show();

							}

						});

					}else {

						Toast.makeText(MainActivity.this, "用户名已被注冊。", 3).show();

					}

				}

				@Override

				public void onError(int arg0, String arg1) {

					// TODO Auto-generated method stub

				}

			});

		}

	}

}

执行实比例如以下：

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