问题

以下是翻译好的部分：

我正在开发一个需要用户认证的 Android 应用程序。我正在使用 localhost 的 phpadmin 用于服务器和数据库连接。到目前为止，该应用程序只有一个登录活动，它导入一个 PHP URL 来连接到 localhost。如果一切正常，该应用程序应该显示一个 alertDialog，表示登录成功。但是，无论我尝试运行应用程序时，当我点击登录时，它都会显示一个空的 alertDialog，并且 Android Studio 的调试器显示以下错误：java.net.ConnectException: Failed to connect to /10.0.2.2:443

这是 MainActivity 的代码：

package com.android.example.meetmev0;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {
    EditText UsernameEt, PasswordEt;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        UsernameEt = (EditText) findViewById(R.id.editTextTextPersonName);
        PasswordEt = (EditText) findViewById(R.id.editTextTextPassword);
    }

    public void OnLogin(View view) {
        String username = UsernameEt.getText().toString();
        String password = PasswordEt.getText().toString();
        BackroundWorker backroundWorker = new BackroundWorker(this);
        String type = "login";
        backroundWorker.execute(type, username, password);
    }
}

这是 BackroundWorker 类的代码：

package com.android.example.meetmev0;

import android.app.AlertDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;

import javax.net.ssl.HttpsURLConnection;

public class BackroundWorker extends AsyncTask<String, Void, String> {
    Context context;
    AlertDialog alertDialog;

    public BackroundWorker(Context ctx) {
        context = ctx;
    }

    @Override
    protected String doInBackground(String... voids) {
        String type = voids[0];
        String login_url = "https://10.0.2.2/MeetLogin.php";
        if (type.equals("login")) {
            try {
                String username = voids[1];
                String password = voids[2];
                URL url = new URL(login_url);
                HttpsURLConnection httpsURLConnection = (HttpsURLConnection) url.openConnection();
                httpsURLConnection.setRequestMethod("POST");
                httpsURLConnection.setDoOutput(true);
                httpsURLConnection.setDoInput(true);
                OutputStream outputStream = httpsURLConnection.getOutputStream();
                BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
                String post_data = URLEncoder.encode("username", "UTF-8") + "=" + URLEncoder.encode(username, "UTF-8") + "&"
                        + URLEncoder.encode("password", "UTF-8") + "=" + URLEncoder.encode(password, "UTF-8");
                bufferedWriter.write(post_data);
                bufferedWriter.flush();
                bufferedWriter.close();
                outputStream.close();
                InputStream inputStream = httpsURLConnection.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "ISO-8859-1"));
                String result = "";
                String line = "";
                while ((line = bufferedReader.readLine()) != null) {
                    result += line;
                }
                bufferedReader.close();
                inputStream.close();
                httpsURLConnection.disconnect();
                Log.v("Activity test:", result);
                return result;
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    @Override
    protected void onPreExecute() {
        alertDialog = new AlertDialog.Builder(context).create();
        alertDialog.setTitle("Login Status");
    }

    @Override
    protected void onPostExecute(String result) {
        alertDialog.setMessage(result);
        alertDialog.show();
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }
}

通过设置断点，我发现这一行 OutputStream outputStream = httpsURLConnection.getOutputStream(); 抛出了异常。

这是我的 AndroidManifest 文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.android.example.meetmev0">
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        android:usesCleartextTraffic="true">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

我尝试添加端口 80、8080 和 8888，但没有成功。将 10.0.2.2 替换为 localhost 或我的本地 IP 也不起作用。

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
public class MainActivity extends AppCompatActivity {
EditText UsernameEt , PasswordEt;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
UsernameEt= (EditText)findViewById(R.id.editTextTextPersonName);
PasswordEt= (EditText)findViewById(R.id.editTextTextPassword);
}
public void OnLogin(View view) {
String username= UsernameEt.getText().toString();
String password= PasswordEt.getText().toString();
BackroundWorker backroundWorker=new BackroundWorker(this);
String type= "login";
backroundWorker.execute(type,username,password);
}
} 

package com.android.example.meetmev0;
import android.app.AlertDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import javax.net.ssl.HttpsURLConnection;
public class BackroundWorker extends AsyncTask<String,Void,String> {
Context context;
AlertDialog alertDialog;
public BackroundWorker ( Context ctx) {
context=ctx;
}
@Override
protected String doInBackground(String... voids) {
String type = voids[0];
String login_url= "https://10.0.2.2/MeetLogin.php";
if(type.equals("login"))
{
String test="so far so good";
try {
String username = voids[1];
String password = voids[2];
URL url= new URL(login_url);
HttpsURLConnection httpsURLConnection = (HttpsURLConnection)url.openConnection();
httpsURLConnection.setRequestMethod("POST");
httpsURLConnection.setDoOutput(true);
httpsURLConnection.setDoInput(true);
OutputStream outputStream= httpsURLConnection.getOutputStream();
test= " still good";
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
String post_data= URLEncoder.encode("username ", "UTF-8")+"="+URLEncoder.encode(username , "UTF-8")+"&"
+URLEncoder.encode("password", "UTF-8")+"="+URLEncoder.encode(password , "UTF-8");
bufferedWriter.write(post_data);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
InputStream inputStream = httpsURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"ISO-8859-1"));
String result="";
String line="";
while((line = bufferedReader.readLine())!=null){
result+=line;
}
bufferedReader.close();
inputStream.close();
httpsURLConnection.disconnect();
Log.v("Activity test: ", result);
return result;
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
@Override
protected void onPreExecute() {
alertDialog= new AlertDialog.Builder(context).create();
alertDialog.setTitle("Login Status");
}
@Override
protected void onPostExecute(String result) {
alertDialog.setMessage(result);
alertDialog.show();
}
@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.example.meetmev0">
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme"
android:usesCleartextTraffic="true">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

答案1

得分: 3

我将"https"更改为"http":

String login_url= "https://10.0.2.2/MeetLogin.php"``` 更改为 ```java String login_url= "http://10.0.2.2/MeetLogin.php"

并且

```java HttpsURLConnection httpsURLConnection = (HttpsURLConnection)url.openConnection();``` 更改为 ```java HttpURLConnection httpsURLConnection = (HttpURLConnection)url.openConnection();```

现在它正常工作。

<details>
<summary>英文:</summary>

I changed https to http: 

`String login_url= &quot;https://10.0.2.2/MeetLogin.php&quot; ` to  `String login_url= &quot;http://10.0.2.2/MeetLogin.php&quot; ` 

and 

` HttpsURLConnection httpsURLConnection = (HttpsURLConnection)url.openConnection(); ` to ` HttpURLConnection httpsURLConnection = (HttpURLConnection)url.openConnection(); `

Now it works perfectly.

</details>