如何解決org.json.JSONException：值<java.lang.String類型的DOCTYPE不能被轉換爲JSONObject的

Question

我目前正在開發一個註冊登錄應用程序。我面臨這個問題，我找不到任何可以解決問題的解決方案。任何人都可以解決這個問題嗎？幫助將不勝感激。

RegisterActivity.java

public class RegisterActivity extends AppCompatActivity { 
AlertDialog.Builder builder; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_register); 

    builder = new AlertDialog.Builder(RegisterActivity.this); 
    final EditText etName = (EditText) findViewById(R.id.etName); 
    final EditText etUserName = (EditText) findViewById(R.id.etUserName); 
    final EditText etPassword = (EditText) findViewById(R.id.etPassword); 
    final EditText etAge = (EditText) findViewById(R.id.etAge); 
    final EditText etEmail = (EditText) findViewById(R.id.etEmail); 
    final Button bRegister = (Button) findViewById(R.id.bRegister); 

    bRegister.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 

      final String name = etName.getText().toString(); 
      final String username = etUserName.getText().toString(); 
      final String password = etPassword.getText().toString(); 
      final int age = Integer.parseInt(etAge.getText().toString()); 
      final String email = etEmail.getText().toString(); 

      if (name.equals("") || username.equals("") || password.equals("") || age == 0 || email.equals("")) { 
       builder.setTitle("Something Went Wrong"); 
       builder.setMessage("Please fill in all the fileds").setPositiveButton("OK", null).create().show(); 

      } else { 

       Response.Listener<String> responseListener = new Response.Listener<String>() { 
        @Override 
        public void onResponse(String response) { 

         try { 
          JSONObject jsonResponse = new JSONObject(response); 
          boolean success = jsonResponse.getBoolean("success"); 

          if (success) { 
           Intent intent = new Intent(RegisterActivity.this, LoginActivity.class); 
           RegisterActivity.this.startActivity(intent); 
          } else { 
           builder = new AlertDialog.Builder(RegisterActivity.this); 
           builder.setMessage("Registration Failed").setNegativeButton("Retry", null).create().show(); 

          } 
         } catch (JSONException e) { 
          e.printStackTrace(); 
         } 
        } 


       }; 
       RegisterRequest registerRequest = new RegisterRequest(name, username, password, age, email, responseListener); 
       RequestQueue queue = Volley.newRequestQueue(RegisterActivity.this); 
       queue.add(registerRequest); 


      } 
     } 

    }); 
} 

Register.php

<?php 

    $servername = "mysql6.000webhost.com"; 
    $username = "a5124128_user"; 
    $password = "paddwoed4896"; 
    $dbname = "a5124128_account"; 


    $con = mysqli_connect($servername, $username, $password, $dbname) or die(mysql_error()); 

    $db_selected = mysql_selectdb($con, $dbname); 

    $name = $_POST["name"]; 
    $username = $_POST["username"]; 
    $password = $_POST["password"]; 
    $age = $_POST["age"]; 
    $email = $_POST["email"]; 

    $statement = mysqli_prepare($con, "INSERT INTO user (name, username, password, age, email) VALUES (?, ?, ?, ?, ?)"); 
    mysqli_stmt_bind_param($statement, "sssis", $name, $username, $password, $age, $email); 
    mysqli_stmt_execute($statement); 

    $response = array();; 
    $response["success"] = true; 

    echo json_encode($response); 

?> 

以下是logcat的

09-25 15:41:50.697 17259-17259/com.example.chang.e_ktm W/System.err: org.json.JSONException: Value <!DOCTYPE of type java.lang.String cannot be converted to JSONObject 
09-25 15:41:50.698 17259-17259/com.example.chang.e_ktm W/System.err:  at org.json.JSON.typeMismatch(JSON.java:111) 
09-25 15:41:50.698 17259-17259/com.example.chang.e_ktm W/System.err:  at org.json.JSONObject.<init>(JSONObject.java:160) 
09-25 15:41:50.698 17259-17259/com.example.chang.e_ktm W/System.err:  at org.json.JSONObject.<init>(JSONObject.java:173) 
09-25 15:41:50.698 17259-17259/com.example.chang.e_ktm W/System.err:  at com.example.chang.e_ktm.RegisterActivity$1$1.onResponse(RegisterActivity.java:78) 
09-25 15:41:50.698 17259-17259/com.example.chang.e_ktm W/System.err:  at com.example.chang.e_ktm.RegisterActivity$1$1.onResponse(RegisterActivity.java:73) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:67) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at android.os.Handler.handleCallback(Handler.java:815) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at android.os.Handler.dispatchMessage(Handler.java:104) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at android.os.Looper.loop(Looper.java:210) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at android.app.ActivityThread.main(ActivityThread.java:5830) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at java.lang.reflect.Method.invoke(Native Method) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at java.lang.reflect.Method.invoke(Method.java:372) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1113) 
09-25 15:41:50.699 17259-17259/com.example.chang.e_ktm W/System.err:  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:879) 

有人可以幫我這個問題？這個問題似乎喜歡上了response.listener

郵差結果

http://i.stack.imgur.com/4dBM6.png

Answer 1

你沒有得到從php api適當的反應發生。所以請檢查api一次使用任何REST client像郵遞員。

Answer 2

「Value <！DOCTYPE」似乎表示您沒有收到JSON有效負載，但是是HTML one。這意味着問題可能會留在您的服務器端，在echo json_encode($response);之前崩潰並生成錯誤頁面（極有可能是'500服務器錯誤'）。

爲了確認，請嘗試從瀏覽器訪問URL發送相同的有效載荷（嘗試GET） - 看看有什麼反應回來。

或者只是開始調試你的PHP腳本里面設置一些斷點，然後觸發從客戶端請求（你設置你的PHP調試到您的IDE，不是嗎？）。