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，客户端使用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 是简单封装 了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
