我在html文件中有一个按钮，当它被按下时，它调用www.example.com中的postData函数MainActivity.java

<script>
document.getElementById("login-button").addEventListener("click", function(event) {
    event.preventDefault();
    var username = document.getElementById("username").value;
    var password = document.getElementById("password").value;
    var role = document.getElementById("role").value;
    var company = document.getElementById("company").value;
    Android.postData(username, password, role, company);
});

MainActivity.java:

public class MainActivity extends AppCompatActivity {
private String username;
private String password;
private String role;
private String company;
private Retrofit retrofit;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    WebView webView = findViewById(R.id.webview);
    webView.getSettings().setJavaScriptEnabled(true);
    webView.addJavascriptInterface(new WebAppInterface(), "Android");
    webView.loadUrl("file:///android_asset/index.html");
}
public class WebAppInterface {
    @JavascriptInterface
    public void postData(String username, String password, String role, String company) {
        try {
            //Test the data is fit with html input
            System.out.println("Username: " + username);
            System.out.println("Password: " + password);
            System.out.println("Role: " + role);
            System.out.println("Company: " + company);
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("username", username);
            jsonObject.put("password", password);
            jsonObject.put("role", role);
            jsonObject.put("company", company);
            String jsonString = jsonObject.toString();
            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.P) {
                new post().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, jsonString);
            } else {
                new post().execute(jsonString);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
class post extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... strings) {
        try {
            // on below line creating a url to post the data.
            URL url = new URL("http://10.0.2.2:3000/login");
            // on below line opening the connection.
            HttpURLConnection client = (HttpURLConnection) url.openConnection();
            // on below line setting method as post.
            client.setRequestMethod("POST");
            // on below line setting content type and accept type.
            client.setRequestProperty("Content-Type", "application/json");
            client.setRequestProperty("Accept", "application/json");
            // on below line setting client.
            client.setDoOutput(true);
            // on below line we are creating an output stream and posting the data.
            try (OutputStream os = client.getOutputStream()) {
                byte[] input = strings[0].getBytes("utf-8");
                os.write(input, 0, input.length);
            }
            // on below line creating and initializing buffer reader.
            try (BufferedReader br = new BufferedReader(
                    new InputStreamReader(client.getInputStream(), "utf-8"))) {
                // on below line creating a string builder.
                StringBuilder response = new StringBuilder();
                // on below line creating a variable for response line.
                String responseLine = null;
                // on below line writing the response
                while ((responseLine = br.readLine()) != null) {
                    response.append(responseLine.trim());
                }
            }
        } catch (Exception e) {
            // on below line handling the exception.
            e.printStackTrace();
        }
        return null;
    }
}

}
提交按钮后Logcat显示：

2023-06-15 05:21:08.684   505-505   AutofillManager         com.example.myapplication            V  requestHideFillUi(null): anchor = null
2023-06-15 05:21:08.763   505-2113  System.out              com.example.myapplication            I  Username: 1
2023-06-15 05:21:08.763   505-2113  System.out              com.example.myapplication            I  Password: 1
2023-06-15 05:21:08.763   505-2113  System.out              com.example.myapplication            I  Role: Company
2023-06-15 05:21:08.763   505-2113  System.out              com.example.myapplication            I  Company: Company 1

这是我的server.js：

app.post('/login', (req, res) => {
    const { username, password, role, company } = req.body;
    // Perform your login logic here
    // For demonstration purposes, let's assume the username is "admin" and password is "password"
    console.log(username, password, role, company);
    if (role === 'Company' && company === 'Company 2' &&
        username === 'admin2' && password === 'password') {
        res.json({ success: true, message: 'org2CreateUser.html' });
    }
    if (role === 'Company' && company === 'Company 1' &&
        username === 'admin1' && password === 'password') {
        res.json({ success: true, message: 'org1CreateUser.html' });
    }
    if (role === 'Employer') {
        credentials.forEach(element => {
            if(element.username === username && element.password == password) {
                res.json({ success: true, message: 'upload.html' });
                return;
            }
        });
        res.status(401).json({ success: false, message: 'Invalid username or password' });
    }
});
app.listen(3000, () => {
    console.log('Server is running on port 3000');
});

问题是我看不到控制台。log（用户名，密码，角色，公司）; respone在服务器的console.log中。当我使用curl测试服务器时，它正常显示：

curl -X POST -H "Content-Type: application/json" -d '{
  "username": "admin",
  "password": "password",
  "role": "Company",
  "company": "Company 1"
}' http://localhost:3000/login

我不知道JSON是否发送到服务器。我在ubuntu vmware中使用Android Studio，并通过usb调试连接我的手机。