思路：
安卓客户端输入账号和密码，使用 okHttp 向服务器端发送请求并传递输入的账号和密码，服务器端的登录接口查询数据库，判断是否能登录成功，然后返回给客户端JSON字符串，客户使用Gson解析服务器返回的数据，做出不同的操作。
服务器端：
1. 数据库
2. 服务器端是 Java Web 用SpringBoot+Mybatis-Plus 快速搭建的，接口返回 map 集合
if(users.size() != 0){ map.put("msg","登录成功"); }else { map.put("msg","账号或密码错误"); } return map;重点是在安卓端
安卓端：
1. 首先弄一个登录页面activity_main.xml出来，相当简陋
<?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <TextView android:id="@+id/textUsername" android:layout_width="wrap_content" android:layout_height="25dp" android:layout_marginStart="4dp" android:layout_marginLeft="4dp" android:text="账号：" app:layout_constraintBottom_toBottomOf="@+id/editUsername" app:layout_constraintEnd_toStartOf="@+id/editUsername" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="@+id/editUsername" /> <TextView android:id="@+id/textPassword" android:layout_width="wrap_content" android:layout_height="23dp" android:layout_marginStart="4dp" android:layout_marginLeft="4dp" android:text="密码：" app:layout_constraintBottom_toBottomOf="@+id/editPassword" app:layout_constraintEnd_toStartOf="@+id/editPassword" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="@+id/editPassword" /> <EditText android:id="@+id/editUsername" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginEnd="23dp" android:layout_marginRight="23dp" android:ems="10" android:hint="请输入用户名/手机号" android:inputType="textPersonName" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toEndOf="@+id/textUsername" app:layout_constraintTop_toTopOf="parent" /> <EditText android:id="@+id/editPassword" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginTop="45dp" android:layout_marginEnd="23dp" android:layout_marginRight="23dp" android:ems="10" android:hint="请输入密码" android:inputType="textPersonName" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toEndOf="@+id/textPassword" app:layout_constraintTop_toBottomOf="@+id/editUsername" /> <Button android:id="@+id/login" android:layout_width="142dp" android:layout_height="42dp" android:layout_marginStart="200dp" android:layout_marginLeft="200dp" android:layout_marginTop="50dp" android:layout_marginEnd="57dp" android:layout_marginRight="57dp" android:text="登录" app:layout_constraintEnd_toEndOf="@+id/editPassword" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/editPassword" /> </androidx.constraintlayout.widget.ConstraintLayout>2. MainActivity.java
public class MainActivity extends AppCompatActivity { private EditText editUsername; private EditText editPassword; //服务器端的登录接口 private String url = "http://192.168.17.xx:8081/user/login"; private String address = null; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //获取用户输入的数据 editUsername = findViewById(R.id.editUsername); editPassword = findViewById(R.id.editPassword); Button login = findViewById(R.id.login); login.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { String username = editUsername.getText().toString(); String password = editPassword.getText().toString(); //向服务器传参 address = url+"?username="+username+"&password="+password; login(); } }); } //登录操作中开启一个子线程 private void login(){ new Thread(new Runnable() { @Override public void run() { try { Response response = HttpUtil.sendOkHttpRequest(address); if(response != null){ String responseData = response.body().string(); Map<String,Object> map = null; //使用Gson解析服务器返回的数据 Gson gson = new Gson(); Type type = new TypeToken<Map<String,Object>>(){}.getType(); map = gson.fromJson(responseData,type); String msg = map.get("msg").toString(); //判断登录成功还是失败，并向主线程传递数据 if("登录成功".equals(msg)){ Message message = new Message(); message.what = 1; message.obj = msg; handler.sendMessage(message); }else{ Message message = new Message(); message.what = 2; message.obj = msg; handler.sendMessage(message); } } } catch (IOException e) { e.printStackTrace(); } } }).start(); } //根据子线程传来数据的不同，进行不同的操作 Handler handler = new Handler(){ public void handleMessage(Message msg){ switch (msg.what){ case 1: String data = (String) msg.obj; Intent intent = new Intent(MainActivity.this,SecondActivity.class); intent.putExtra("msg",data); startActivity(intent); break; case 2: String data2 = (String) msg.obj; Toast.makeText(MainActivity.this, data2, Toast.LENGTH_SHORT).show(); } } }; }
- 其中 String url = "http://192.168.17.99:8081/user/login" 是服务器端的登录接口
- SecondActivity 就是打开一个空白的页面activity_second.xml，就不粘代码了
- HttpUtil 是自己封装的 okHttp
public class HttpUtil { public static Response sendOkHttpRequest(String address) { OkHttpClient client = new OkHttpClient(); Request request = new Request.Builder() .url(address) .build(); try { Response response = client.newCall(request).execute(); return response; } catch (IOException e) { e.printStackTrace(); return null; } } }3. 其他要注意的地方
- okhttp 和 gson 依赖应该添加好
implementation 'com.squareup.okhttp3:okhttp:4.2.2' implementation 'com.google.code.gson:gson:2.7'
- AndroidManifest.xml 打开权限
<uses-permission android:name="android.permission.INTERNET" /> android:usesCleartextTraffic="true" //使用明文传输4. 最后运行服务器端代码，让手机和服务器端处于同一网络，就能测试登录了
