Android JSON，其中Volley和PHP的输入结尾为
Android JSON，其中Volley和PHP的输入结尾为
提问于 2018-07-31 11:52:04
我正在编写一个应用程序，需要使用存储在数据库中的联系人，所以我正在使用wammp和PHPMyAdmin来编写一个简单的REST API。我已经编写了涉及注册和登录的部分，但由于某些原因，我无法让联系人的存储工作，即使我认为这几乎是一样的事情逐字。我得到了一个异常：
org.json.JSONException: End of input at character 0 of我到处寻找这个问题，看起来我传递回我的应用程序的JSON是空的，所以我意识到了这个问题，但无论在哪里，解决方案都没有帮助我解决这个问题，所以我觉得这可能是一个独特的问题。以下是我的相关Android代码：
// Create the new string request
StringRequest stringRequest = new StringRequest(Request.Method.POST, AppConfig.URL_NEW_CONTACT, new Response.Listener<String>()
{
@Override
public void onResponse(String response)
{
// Log method entry
MethodLogger methodLogger = new MethodLogger();
// Log the JSON that was returned
methodLogger.d("New Contact Response: " + response.toString());
// Remove the processing view
hideDialog();
// Try to retrieve JSON and parse through it
try
{
JSONObject jObj = new JSONObject(response);
// Check for errors in the JSON passed back
boolean error = jObj.getBoolean("error");
/*----------------------------------------------------------------*
* If there was no error found *
*----------------------------------------------------------------*/
if (!error)
{
// Indicate the success to the user
Toast.makeText(getApplicationContext(), "Contact successfully created.", Toast.LENGTH_LONG).show();
// Take the user back to the contact page
routeToContactPage();
}
/*----------------------------------------------------------------*
* Else if there was an error found *
*----------------------------------------------------------------*/
else
{
// Notify the user
String errorMsg = jObj.getString("message");
Toast.makeText(getApplicationContext(),
errorMsg, Toast.LENGTH_LONG).show();
}
}
/*--------------------------------------------------------------------*
* Catch any error in retrieving parsing etc JSON *
*--------------------------------------------------------------------*/
catch (JSONException e)
{
e.printStackTrace();
Toast.makeText(getApplicationContext(), "Error storing contact: " + e.getMessage(), Toast.LENGTH_LONG).show();
}
// Log method exit
methodLogger.end();
}
}, new Response.ErrorListener()
{
@Override
public void onErrorResponse(VolleyError error)
{
// Log method entry
MethodLogger methodLogger = new MethodLogger();
// Notify the user
methodLogger.e("Error storing contact: " + error.getMessage());
Toast.makeText(getApplicationContext(),
error.getMessage(), Toast.LENGTH_LONG).show();
hideDialog();
// Log method exit
methodLogger.end();
}
})
{
@Override
protected Map<String, String> getParams()
{
// Log method entry
MethodLogger methodLogger = new MethodLogger();
// create a new params object and add the contact data
Map<String, String> params = new HashMap<String, String>();
// Add the params to the volley request
params.put("user_id", SessionManager.getUser().getId());
params.put("name", name);
params.put("email", emailAddress);
// Log method exit
methodLogger.end();
// Return the user data
return params;
}
};
// Send the request string to the request queue to be sent to the PHP API
AppController.getInstance().addToRequestQueue(stringRequest, tag_string_req);
}相关PHP代码：
存储联系人：
public function storeContact($name, $email, $user_id)
{
$uuid = uniqid('', true);
$result = mysqli_query($this->conn, "INSERT INTO contacts (unique_id, name, email, created_at, updated_at, user_id) VALUES ('$uuid', '$name', '$email', NOW(), NULL, '$user_id')") or die (mysql_error());
if ($result)
{
$contact = mysqli_query($this->conn, "SELECT * FROM contacts WHERE name = '$name' AND user_id = '$user_id'");
return $contact;
}
else
{
return false;
}
}与服务器/应用程序通信：
<?php
require_once 'include/DB_Functions.php';
$db = new DB_Functions();
$response = array();
if (isset($_POST['user_id']) && isset($_POST['name']) && isset($_POST['email']))
{
$user_id = $_POST['user_id'];
$name = $_POST['name'];
$email = $_POST['email'];
$result = $db->storeContact($name, $email, $user_id);
if ($result)
{
$response["error"] = FALSE;
$response["message"] = "Contact stored successfully";
}
else
{
$response["error"] = TRUE;
$response["message"] = "Unknown error occurred in storing contact";
}
}
else
{
$response["error"] = TRUE;
$response["message"] = "Required parameters, name, email, or user_id, missing";
}
echo json_encode($response);
?>最后，相关的logcat输出：
07-30 22:39:07.408 24212-24212/com.example.e4977.spotme D/com.example.e4977.spotme.AppController: Method Entry: getInstance()
getInstance() finished in 0.000 seconds.
Method Entry: addToRequestQueue()
07-30 22:39:07.409 24212-24212/com.example.e4977.spotme D/com.example.e4977.spotme.AppController: Method Entry: getRequestQueue()
getRequestQueue() finished in 0.000 seconds.
07-30 22:39:07.410 24212-24212/com.example.e4977.spotme D/com.example.e4977.spotme.AppController: addToRequestQueue() finished in 0.001 seconds.
07-30 22:39:07.410 24212-24212/com.example.e4977.spotme D/com.example.e4977.spotme.ContactActivity: onCreate() finished in 0.072 seconds.
07-30 22:39:07.424 24212-31569/com.example.e4977.spotme D/com.example.e4977.spotme.ContactActivity$3: Method Entry: getParams()
07-30 22:39:07.425 24212-31569/com.example.e4977.spotme D/com.example.e4977.spotme.ContactActivity$3: getParams() finished in 0.000 seconds.
07-30 22:39:07.426 24212-24212/com.example.e4977.spotme D/com.example.e4977.spotme.NewContactActivity$1$1: Method Entry: onResponse()
onResponse() New Contact Response:
07-30 22:39:07.426 24212-24212/com.example.e4977.spotme D/com.example.e4977.spotme.NewContactActivity: Method Entry: hideDialog()
07-30 22:39:07.448 24212-24212/com.example.e4977.spotme D/com.example.e4977.spotme.NewContactActivity: hideDialog() finished in 0.021 seconds.
07-30 22:39:07.448 24212-24212/com.example.e4977.spotme W/System.err: org.json.JSONException: End of input at character 0 of
at org.json.JSONTokener.syntaxError(JSONTokener.java:449)
at org.json.JSONTokener.nextValue(JSONTokener.java:97)
at org.json.JSONObject.<init>(JSONObject.java:159)
at org.json.JSONObject.<init>(JSONObject.java:176)
at com.example.e4977.spotme.NewContactActivity$1$1.onResponse(NewContactActivity.java:119)
07-30 22:39:07.449 24212-24212/com.example.e4977.spotme W/System.err: at com.example.e4977.spotme.NewContactActivity$1$1.onResponse(NewContactActivity.java:99)
at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:60)
at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30)
at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
at android.os.Handler.handleCallback(Handler.java:789)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6798)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
07-30 22:39:07.454 24212-24212/com.example.e4977.spotme D/com.example.e4977.spotme.NewContactActivity$1$1: onResponse() finished in 0.027 seconds.同样值得注意的是，我看到响应是空的，但我不知道为什么。下面是数据库模式，以防这也是问题的一部分。
回答 1
Stack Overflow用户
回答已采纳
发布于 2018-08-01 13:00:01
回答
我非常确定这是因为您正在使用mysqli_*函数集，但随后尝试使用mysql_error获取最新的错误文本，它将返回一个空字符串，因为对mysql_*函数的调用没有任何错误。
尝试替换：
$result = mysqli_query($this->conn, /* the rest */) or die (mysql_error());通过以下方式：
$result = mysqli_query($this->conn, /* the rest */) or die (mysqli_error($this->conn));您仍然会抛出一个异常，类似于：
org.json.JSONException: Value Data of type java.lang.String cannot be converted to JSONObject因为响应将不是有效的JSON，但这应该会对您有所帮助。
旁注
因为这是一个非常典型的问题，所以我不得不在您发布的代码中对SQL注入问题进行评论。有必要通读一下https://cwe.mitre.org/data/definitions/89.html来理解这个问题，然后看看http://php.net/manual/en/mysqli.quickstart.prepared-statements.php，看看如何使用mysqli_prepare、mysqli_stmt_bind_param和mysqli_stmt_execute来组合一个更安全的实现。
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原文链接：
https://stackoverflow.com/questions/51605210
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