我正在研究 JSON 数据解析，我是新手，因为我是第一次进行 JSON 解析。我尝试了这个链接中的一个例子。它运行良好。但是当我根据需要更改示例代码时出现错误。我更改的代码如下：
MainActivity.Java
public class MainActivity extends ListActivity {
private ProgressDialog pDialog;
// URL to get contacts JSON
private static String url = "https://123.xxx.x.xxx/DEMO/login_data.php";
// JSON Node names
private static final String TAG_STATUS = "Status";
private static final String TAG_USERNAME = "User Name";
private static final String TAG_PASSWORD = "Admin password";
// contacts JSONArray
JSONArray sampleData = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> userNamePass;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
userNamePass = new ArrayList<HashMap<String, String>>();
ListView lv = getListView();
// Listview on item click listener
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String cost = ((TextView) view.findViewById(R.id.password))
.getText().toString();
// Starting single contact activity
Intent in = new Intent(getApplicationContext(),SingleContactActivity.class);
in.putExtra(TAG_USERNAME, name);
in.putExtra(TAG_PASSWORD, cost);
startActivity(in);
}
});
// Calling async task to get json
new GetContacts().execute();
}
/**
* Async task class to get json by making HTTP call
* */
private class GetContacts extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.POST);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
sampleData = jsonObj.getJSONArray(TAG_STATUS);
// looping through All Contacts
for (int i = 0; i < sampleData.length(); i++) {
JSONObject c = sampleData.getJSONObject(i);
String name = c.getString(TAG_USERNAME);
String password = c.getString(TAG_PASSWORD);
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_USERNAME, name);
contact.put(TAG_PASSWORD, password);
// adding contact to contact list
userNamePass.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, userNamePass,
R.layout.list_item, new String[] { TAG_USERNAME, TAG_PASSWORD }, new int[] { R.id.name,
R.id.password });
setListAdapter(adapter);
}
}
}
服务处理器.Java
public class ServiceHandler {
static String response = null;
public final static int GET = 1;
public final static int POST = 2;
public ServiceHandler() {
}
/*
* Making service call
* @url - url to make request
* @method - http request method
* */
public String makeServiceCall(String url, int method) {
return this.makeServiceCall(url, method, null);
}
/*
* Making service call
* @url - url to make request
* @method - http request method
* @params - http request params
* */
public String makeServiceCall(String url, int method,
List<NameValuePair> params) {
try {
// http client
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpEntity httpEntity = null;
HttpResponse httpResponse = null;
// Checking http request method type
if (method == POST) {
HttpPost httpPost = new HttpPost(url);
// adding post params
if (params != null) {
httpPost.setEntity(new UrlEncodedFormEntity(params));
}
httpResponse = httpClient.execute(httpPost);
} else if (method == GET) {
// appending params to url
if (params != null) {
String paramString = URLEncodedUtils
.format(params, "utf-8");
url += "?" + paramString;
}
HttpGet httpGet = new HttpGet(url);
httpResponse = httpClient.execute(httpGet);
}
httpEntity = httpResponse.getEntity();
response = EntityUtils.toString(httpEntity);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return response;
}
}
SingleContactActivity.Java
public class SingleContactActivity extends Activity {
// JSON node keys
private static final String TAG_NAME = "name";
private static final String TAG_PASSWORD = "password";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_single_contact);
// getting intent data
Intent in = getIntent();
// Get JSON values from previous intent
String name = in.getStringExtra(TAG_NAME);
String password = in.getStringExtra(TAG_PASSWORD);
// Displaying all values on the screen
TextView lblName = (TextView) findViewById(R.id.name_label);
TextView lblPassword = (TextView) findViewById(R.id.password_label);
lblName.setText(name);
lblPassword.setText(password);
}
}
我在运行时遇到的错误：
02-24 17:34:25.190: W/System.err(14285): org.apache.http.conn.ConnectTimeoutException: Connect to /123.xxx.x.xxx:443 timed out
02-24 17:34:25.190: W/System.err(14285): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:121)
02-24 17:34:25.190: W/System.err(14285): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:156)
02-24 17:34:25.195: W/System.err(14285): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
02-24 17:34:25.195: W/System.err(14285): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
02-24 17:34:25.195: W/System.err(14285): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:359)
02-24 17:34:25.195: W/System.err(14285): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
02-24 17:34:25.200: W/System.err(14285): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
02-24 17:34:25.200: W/System.err(14285): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
02-24 17:34:25.200: W/System.err(14285): at com.oi.jsonparsingdemo.ServiceHandler.makeServiceCall(ServiceHandler.java:59)
02-24 17:34:25.205: W/System.err(14285): at com.oi.jsonparsingdemo.ServiceHandler.makeServiceCall(ServiceHandler.java:34)
02-24 17:34:25.210: W/System.err(14285): at com.oi.jsonparsingdemo.MainActivity$GetContacts.doInBackground(MainActivity.java:99)
02-24 17:34:25.210: W/System.err(14285): at com.oi.jsonparsingdemo.MainActivity$GetContacts.doInBackground(MainActivity.java:1)
02-24 17:34:25.215: W/System.err(14285): at android.os.AsyncTask$2.call(AsyncTask.java:185)
02-24 17:34:25.215: W/System.err(14285): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
02-24 17:34:25.215: W/System.err(14285): at java.util.concurrent.FutureTask.run(FutureTask.java:138)
02-24 17:34:25.220: W/System.err(14285): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
02-24 17:34:25.220: W/System.err(14285): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
02-24 17:34:25.220: W/System.err(14285): at java.lang.Thread.run(Thread.java:1019)
02-24 17:34:25.220: D/Response:(14285): > null
02-24 17:34:25.220: E/ServiceHandler(14285): Couldn't get any data from the url
02-24 17:34:25.280: D/CLIPBOARD(14285): Hide Clipboard dialog at Starting input: finished by someone else... !
我在哪里错了，或者我应该遵循哪些步骤才能完成我的任务。请提出您宝贵的建议...