Java json解析器在从json格式的web服务获取时发生异常_Java_Android

Java json解析器在从json格式的web服务获取时发生异常

java android

Java json解析器在从json格式的web服务获取时发生异常,java,android,Java,Android,我很困惑为什么会出现这些错误，而事实上，我创建的GAE应用程序中的web服务返回的是完全相同的JSON格式您可以检查此url： http://dashproapp.appspot.com/rest/user 它正在返回json格式以下是使用结果的代码： JSONParser jParser = new JSONParser(); // getting JSON string from URL JSONObject json = jParser.getJSONFromUr

我很困惑为什么会出现这些错误，而事实上，我创建的GAE应用程序中的web服务返回的是完全相同的JSON格式

您可以检查此url：

http://dashproapp.appspot.com/rest/user

它正在返回json格式

以下是使用结果的代码：

JSONParser jParser = new JSONParser();
    // getting JSON string from URL
    JSONObject json = jParser.getJSONFromUrl(url_path);

    try {
        // Getting Array of users
        userlist = json.getJSONArray(TAG_USER);

        // looping through All USERS obtain from results
        for(int i = 0; i < userlist.length(); i++){
            JSONObject c = userlist.getJSONObject(i);

            // Storing each json item in variable
            String address = c.getString(TAG_ADDRESS);              
            String id = c.getString(TAG_ID);
            String age = c.getString(TAG_AGE);
            String fname = c.getString(TAG_FNAME);
            String lname = c.getString(TAG_LNAME);
            String username = c.getString(TAG_USERNAME);
            String password = c.getString(TAG_PASSWORD);

这就是错误：

Error parsing data org.json.JSONException: Value <!DOCTYPE of type java.lang.String cannot be converted to JSONObject

日志cat输出：

12-13 09:20:18.632: I/ApplicationPackageManager(32494): cscCountry is not German : XTC
12-13 09:20:32.289: D/dalvikvm(32494): GC_CONCURRENT freed 107K, 45% free 3155K/5639K, external 499K/517K, paused 4ms+15ms
12-13 09:20:32.632: E/JSON Parser(32494): Error parsing data org.json.JSONException: Value <html><body><h1>Server of type java.lang.String cannot be converted to JSONObject
12-13 09:20:32.640: D/AndroidRuntime(32494): Shutting down VM
12-13 09:20:32.640: W/dalvikvm(32494): threadid=1: thread exiting with uncaught exception (group=0x40018578)
12-13 09:20:32.640: E/AndroidRuntime(32494): FATAL EXCEPTION: main
12-13 09:20:32.640: E/AndroidRuntime(32494): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.pruce.aps.estateportalconsume/com.pruce.aps.estateportalconsume.MainActivity}: java.lang.NullPointerException
12-13 09:20:32.640: E/AndroidRuntime(32494):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at android.os.Handler.dispatchMessage(Handler.java:99)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at android.os.Looper.loop(Looper.java:130)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at android.app.ActivityThread.main(ActivityThread.java:3687)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at java.lang.reflect.Method.invokeNative(Native Method)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at java.lang.reflect.Method.invoke(Method.java:507)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at dalvik.system.NativeStart.main(Native Method)
12-13 09:20:32.640: E/AndroidRuntime(32494): Caused by: java.lang.NullPointerException
12-13 09:20:32.640: E/AndroidRuntime(32494):    at    com.pruce.aps.estateportalconsume.MainActivity.onCreate(MainActivity.java:54)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-13 09:20:32.640: E/AndroidRuntime(32494):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
12-13 09:20:32.640: E/AndroidRuntime(32494):    
... 11 more

我使用了我在这里找到的教程在我的android应用程序中使用JSON。我尝试使用这种架构，我将使用GAE作为我的服务器，接受数据，返回json格式的数据

这里是整个班级

private static String url_path = "http://dashproapp.appspot.com/rest/user/";
    private static final String TAG_USER = "user_list";
    private static final String TAG_ID = "id"; 
    private static String TAG_FNAME = "firstname";
    private static String TAG_LNAME = "lastname";
    private static String TAG_AGE = "age";
    private static String TAG_ADDRESS = "address";
    private static String TAG_USERNAME = "username";
    private static String TAG_PASSWORD = "password";


    //store in array first
    JSONArray userlist = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Hashmap for ListView
        ArrayList<HashMap<String, String>> userList = new ArrayList<HashMap<String, String>>();

        // instantiate json for parsing list obtain from above
        JSONParser jParser = new JSONParser();

        // getting JSON string from URL
        JSONObject json = jParser.getJSONFromUrl(url_path);
        //ArrayList<JSONObject> arrays = new ArrayList<JSONObject>();

        try {
            // Getting Array of users
            userlist = json.getJSONArray(TAG_USER);

            // looping through All USERS obtain from results
            for(int i = 0; i < userlist.length(); i++){
                JSONObject c = userlist.getJSONObject(i);

                //arrays.add(c);                            
                // Storing each json item in variable
                String address = c.getString(TAG_ADDRESS);              
                String id = c.getString(TAG_ID);
                String age = c.getString(TAG_AGE);
                String fname = c.getString(TAG_FNAME);
                String lname = c.getString(TAG_LNAME);
                String username = c.getString(TAG_USERNAME);
                String password = c.getString(TAG_PASSWORD);

                // creating new HashMap
                HashMap<String, String> map = new HashMap<String, String>();

                // adding each child node to HashMap key => value
                map.put(TAG_ADDRESS, address);
                map.put(TAG_ID, id);
                map.put(TAG_AGE, age);
                map.put(TAG_FNAME, fname);
                map.put(TAG_LNAME, lname);
                map.put(TAG_USERNAME, username);
                map.put(TAG_PASSWORD, password);

                // adding HashList to ArrayList
                userList.add(map);
            }
            //JSONObject[] jsons = new JSONObject[arrays.size()];
            //arrays.toArray(jsons);
            //System.out.print(arrays.get(1));
        } catch (JSONException e) {
            e.printStackTrace();
        }

请张贴整个StackTrace，你可以张贴静态定义吗