目前，我的PHP文件用于MySQL服务器和我的Android应用程序之间的接口，看起来像：
<?php
// array for JSON response
$response = array();
if (isset($_GET['porfileID'])) {
$ID = $_GET['porfileID'];
// include db connect class
require_once __DIR__ . '/db_connect.php';
// connecting to db
$db = new DB_CONNECT();
// get all products from products table
$result = mysql_query("SELECT * FROM profiles_profilelists WHERE ProfileID = '$ID'") or die(mysql_error());
// check for empty result
if (mysql_num_rows($result) > 0) {
// looping through all results
// products node
$response["lists"] = array();
while ($row = mysql_fetch_array($result)) {
// temp user array
$lists = array();
$lists["ProfileListID"] = $row["ProfileListID"];
$lists["ProfileListName"] = $row["ProfileListName"];
// push single product into final response array
array_push($response["lists"], $lists);
}
// success
$response["success"] = 1;
// echoing JSON response
echo json_encode($response);
} else {
// no products found
$response["success"] = 0;
$response["message"] = "No products found";
// echo no users JSON
echo json_encode($response);
}
} else {
// required field is missing
$response["success"] = 0;
$response["message"] = "Required field(s) is missing";
// echoing JSON response
echo json_encode($response);
}
?>
然而，当我添加时，这很好
$result2 = mysql_query("SELECT * FROM profiles_profilelistitems WHERE ProfileListID = ".$row["ProfileListName"]) or die(mysql_error());
$lists["ListCount"] = mysql_num_rows($result2);
对我的博士来说，它看起来像：
<?php
// array for JSON response
$response = array();
if (isset($_GET['porfileID'])) {
$ID = $_GET['porfileID'];
// include db connect class
require_once __DIR__ . '/db_connect.php';
// connecting to db
$db = new DB_CONNECT();
// get all products from products table
$result = mysql_query("SELECT * FROM profiles_profilelists WHERE ProfileID = '$ID'") or die(mysql_error());
// check for empty result
if (mysql_num_rows($result) > 0) {
// looping through all results
// products node
$response["lists"] = array();
while ($row = mysql_fetch_array($result)) {
// temp user array
$lists = array();
$lists["ProfileListID"] = $row["ProfileListID"];
$lists["ProfileListName"] = $row["ProfileListName"];
$result2 = mysql_query("SELECT * FROM profiles_profilelistitems WHERE ProfileListID = ".$row["ProfileListName"]) or die(mysql_error());
$lists["ListCount"] = mysql_num_rows($result2);
// push single product into final response array
array_push($response["lists"], $lists);
}
// success
$response["success"] = 1;
// echoing JSON response
echo json_encode($response);
} else {
// no products found
$response["success"] = 0;
$response["message"] = "No products found";
// echo no users JSON
echo json_encode($response);
}
} else {
// required field is missing
$response["success"] = 0;
$response["message"] = "Required field(s) is missing";
// echoing JSON response
echo json_encode($response);
}
?>
我最后犯了上述错误。完整的轨迹是：
09-03 17:05:57.836: E/JSON Parser(675): Error parsing data org.json.JSONException: Value You of type java.lang.String cannot be converted to JSONObject
09-03 17:05:59.617: E/AndroidRuntime(675): FATAL EXCEPTION: AsyncTask #1
09-03 17:05:59.617: E/AndroidRuntime(675): java.lang.RuntimeException: An error occured while executing doInBackground()
09-03 17:05:59.617: E/AndroidRuntime(675): at android.os.AsyncTask$3.done(AsyncTask.java:299)
09-03 17:05:59.617: E/AndroidRuntime(675): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
09-03 17:05:59.617: E/AndroidRuntime(675): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
09-03 17:05:59.617: E/AndroidRuntime(675): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
09-03 17:05:59.617: E/AndroidRuntime(675): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
09-03 17:05:59.617: E/AndroidRuntime(675): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
09-03 17:05:59.617: E/AndroidRuntime(675): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
09-03 17:05:59.617: E/AndroidRuntime(675): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
09-03 17:05:59.617: E/AndroidRuntime(675): at java.lang.Thread.run(Thread.java:856)
09-03 17:05:59.617: E/AndroidRuntime(675): Caused by: java.lang.NullPointerException
09-03 17:05:59.617: E/AndroidRuntime(675): at com.test.app.MyLists$LoadAllLists.doInBackground(MyLists.java:267)
09-03 17:05:59.617: E/AndroidRuntime(675): at com.test.app.MyLists$LoadAllLists.doInBackground(MyLists.java:1)
09-03 17:05:59.617: E/AndroidRuntime(675): at android.os.AsyncTask$2.call(AsyncTask.java:287)
09-03 17:05:59.617: E/AndroidRuntime(675): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
09-03 17:05:59.617: E/AndroidRuntime(675): ... 5 more
跟踪从应用程序中链接到的代码：
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("porfileID", Integer.toString(userID)));
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray("lists");
productsList.clear();
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String id = c.getString("ProfileListID");
String name = c.getString("ProfileListName");
//String count = c.getString("ListCount");
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put("ProfileListID", id);
map.put("ProfileListName", name);
// adding HashList to ArrayList
productsList.add(map);
}
} else {
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
最后是我使用的json解析器
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
// function get json from url
// by making HTTP POST or GET method
public JSONObject makeHttpRequest(String url, String method,
List<NameValuePair> params) {
// Making HTTP request
try {
// check for request method
if(method == "POST"){
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}else if(method == "GET"){
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpGet);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "'n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
如果在引入PHP行之后才出现错误，那么查询本身可能会出现错误。尝试转储查询以获得更多见解。
SELECT * FROM profiles_profilelistitems WHERE ProfileListID = ".$row["ProfileListName"]
应该是
SELECT * FROM profiles_profilelistitems WHERE ProfileListID = '".$row["ProfileListName"]."'"
问题仅在php中，请重写查询或检查php。我也遇到过同样的问题，这个问题不在android或任何东西中，它只在php中，通常在查询中。若查询似乎正确，那个么也重写一次查询。