我编写了一个 java restful web 服务并将其部署在 ec2 实例上，并以 tomcat7 作为服务器。我正在尝试从 Web 服务检索响应对象中的 json 数组。我的响应对象是这样的：-
{
"Transactional": [
{
"a": "Y",
"a1": "4",
"a2": "5",
"a3": "0",
"a4": "1",
"a5": "4",
"a6": "3",
"a7": "6",
"a8": "9",
"a9": "5",
"b_MovieID": "0",
"c": "N",
"c1": "0",
"c2": "0",
"c3": "0",
"c4": "0",
"c5": "0",
"c6": "0",
"d": "N",
"d1": "0",
"d2": "0",
"d3": "0",
"d4": "0",
"d5": "0",
"d6": "0",
"d7": "0",
"g1": "10",
"g2": "8",
"g3": "2",
"g4": "8",
"g5": "0",
"g6": "7",
"g7": "8",
"h": "N",
"h1": "0",
"h2": "0",
"h3": "0",
"h4": "0",
"h5": "0",
"h6": "0",
"movieID": "1",
"r": "N",
"r1": "0",
"r2": "0",
"r3": "0",
"r4": "0",
"r5": "0",
"r6": "0",
"r7": "0",
"s": "N",
"s1": "0",
"s2": "0",
"s3": "0",
"s4": "0",
"s5": "0",
"s6": "0",
"SB": "N",
"SB1": "0",
"SB2": "0",
"SB3": "0",
"SB4": "0",
"SP": "N",
"SP1": "0",
"SP2": "0",
"SP3": "0",
"t": "N",
"t1": "0",
"t2": "0",
"t3": "0",
"t4": "0",
"t5": "0",
"t6": "0",
"t7": "0",
"t8": "0",
"t9": "0",
"TA1": "N",
"TA2": "N",
"TA3": "N",
"TC1": "N",
"TC2": "N",
"TG1": "N",
"TG2": "N",
"TG3": "N",
"TG4": "N",
"TG5": "N",
"TH1": "N",
"TH2": "N",
"TH3": "N",
"TR1": "N",
"TS1": "N",
"TS2": "N",
"TSB1": "N",
"TSP1": "N",
"TW1": "N",
"w": "N",
"w1": "0",
"w2": "0",
"w3": "0",
"w4": "0",
"w5": "0"
},
{
"a": "Y",
"a1": "1",
"a2": "6",
"a3": "0",
"a4": "4",
"a5": "3",
"a6": "4",
"a7": "2",
"a8": "3",
"a9": "4",
"b_MovieID": "0",
"c": "N",
"c1": "0",
"c2": "0",
"c3": "0",
"c4": "0",
"c5": "0",
"c6": "0",
"d": "N",
"d1": "0",
"d2": "0",
"d3": "0",
"d4": "0",
"d5": "0",
"d6": "0",
"d7": "0",
"g1": "5",
"g2": "6",
"g3": "6",
"g4": "7",
"g5": "0",
"g6": "8",
"g7": "7",
"h": "N",
"h1": "0",
"h2": "0",
"h3": "0",
"h4": "0",
"h5": "0",
"h6": "0",
"movieID": "2",
"r": "N",
"r1": "0",
"r2": "0",
"r3": "0",
"r4": "0",
"r5": "0",
"r6": "0",
"r7": "0",
"s": "N",
"s1": "0",
"s2": "0",
"s3": "0",
"s4": "0",
"s5": "0",
"s6": "0",
"SB": "N",
"SB1": "0",
"SB2": "0",
"SB3": "0",
"SB4": "0",
"SP": "N",
"SP1": "0",
"SP2": "0",
"SP3": "0",
"t": "N",
"t1": "0",
"t2": "0",
"t3": "0",
"t4": "0",
"t5": "0",
"t6": "0",
"t7": "0",
"t8": "0",
"t9": "0",
"TA1": "N",
"TA2": "N",
"TA3": "N",
"TC1": "N",
"TC2": "N",
"TG1": "N",
"TG2": "N",
"TG3": "N",
"TG4": "N",
"TG5": "N",
"TH1": "N",
"TH2": "N",
"TH3": "N",
"TR1": "N",
"TS1": "N",
"TS2": "N",
"TSB1": "N",
"TSP1": "N",
"TW1": "N",
"w": "N",
"w1": "0",
"w2": "0",
"w3": "0",
"w4": "0",
"w5": "0"
}
]
}
我正在尝试使用以下代码在我的 android 应用程序中的 java 中检索它：-
try {
JSONObject jsonObj = new JSONObject(response);
JSONArray jsonArr;
jsonArr = jsonObj.getJSONArray("Transactional");
for (int i = 0; i < jsonArr.length(); i++) {
JSONObject obj = jsonArr.getJSONObject(i);
try {
int A1 = obj.getInt("a1");
System.out.println("A1 value : " + A1);
break;
} catch (JSONException ex) {
}
}
这是从 json 数组中检索数据的正确方法吗？我收到以下错误：-
12-14 11:11:56.526: E/WebServiceTask(18921): ec2-xx-xx-xxx-xxx.compute-1.amazonaws.com
12-14 11:11:56.526: E/WebServiceTask(18921): java.net.UnknownHostException: ec2-xx-xx-xxx-xxx.compute-1.amazonaws.com
12-14 11:11:56.526: E/WebServiceTask(18921): at java.net.InetAddress.lookupHostByName(InetAddress.java:506)
12-14 11:11:56.526: E/WebServiceTask(18921): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:294)
12-14 11:11:56.526: E/WebServiceTask(18921): at java.net.InetAddress.getAllByName(InetAddress.java:256)
12-14 11:11:56.526: E/WebServiceTask(18921): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:136)
12-14 11:11:56.526: E/WebServiceTask(18921): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
12-14 11:11:56.526: E/WebServiceTask(18921): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
12-14 11:11:56.526: E/WebServiceTask(18921): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:359)
12-14 11:11:56.526: E/WebServiceTask(18921): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
12-14 11:11:56.526: E/WebServiceTask(18921): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
12-14 11:11:56.526: E/WebServiceTask(18921): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
12-14 11:11:56.526: E/WebServiceTask(18921): at com.movies.CategorySelection$WebServiceTask.doResponse(SubCategorySelection.java:248)
12-14 11:11:56.526: E/WebServiceTask(18921): at com.movies.CategorySelection$WebServiceTask.doInBackground(SubCategorySelection.java:147)
12-14 11:11:56.526: E/WebServiceTask(18921): at com.movies.CategorySelection$WebServiceTask.doInBackground(SubCategorySelection.java:1)
12-14 11:11:56.526: E/WebServiceTask(18921): at android.os.AsyncTask$2.call(AsyncTask.java:185)
12-14 11:11:56.526: E/WebServiceTask(18921): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
12-14 11:11:56.526: E/WebServiceTask(18921): at java.util.concurrent.FutureTask.run(FutureTask.java:138)
12-14 11:11:56.526: E/WebServiceTask(18921): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
12-14 11:11:56.526: E/WebServiceTask(18921): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
12-14 11:11:56.526: E/WebServiceTask(18921): at java.lang.Thread.run(Thread.java:1019)
12-14 11:11:56.576: E/SubCategorySelection(18921): Error parsing data org.json.JSONException: End of input at character 0 of
尽管我知道我遇到了未知主机异常，但我可以在同一主机中的示例 url 上轻松检索示例数据
http://ec2-xx-xx-xxx-xxx.compute-1.amazonaws.com:8080/MovieAppRestWebService/rest/movie/sample
这可能意味着我解析数据的方式有问题。谁能帮忙！
这是我调用网络服务的方式：-
private static final String SERVICE_URL_ACTION = "http://ec2-xx-xx-xxx-xxx.compute-1.amazonaws.com:8080/MovieAppRestWebService/rest/movie/A";
Button bNext = (Button) findViewById(R.id.btnNext);
bNext.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
retrieveSampleData(v);
}
});
public void retrieveSampleData(View vw) {
WebServiceTask wst = new WebServiceTask(WebServiceTask.GET_TASK, this,
"GETting data...");
wst.execute(new String[] { SERVICE_URL_ACTION });
}
private class WebServiceTask extends AsyncTask<String, Integer, String> {
public static final int POST_TASK = 1;
public static final int GET_TASK = 2;
private static final String TAG = "WebServiceTask";
// connection timeout, in milliseconds (waiting to connect)
private static final int CONN_TIMEOUT = 3000;
// socket timeout, in milliseconds (waiting for data)
private static final int SOCKET_TIMEOUT = 5000;
private int taskType = GET_TASK;
private Context mContext = null;
private String processMessage = "Processing...";
private ArrayList<NameValuePair> params = new ArrayList<NameValuePair>();
private ProgressDialog pDlg = null;
public WebServiceTask(int taskType, Context mContext,
String processMessage) {
this.taskType = taskType;
this.mContext = mContext;
this.processMessage = processMessage;
}
@SuppressWarnings("deprecation")
private void showProgressDialog() {
pDlg = new ProgressDialog(mContext);
pDlg.setMessage(processMessage);
pDlg.setProgressDrawable(mContext.getWallpaper());
pDlg.setProgressStyle(ProgressDialog.STYLE_SPINNER);
pDlg.setCancelable(false);
pDlg.show();
}
@Override
protected void onPreExecute() {
hideKeyboard();
showProgressDialog();
}
protected String doInBackground(String... urls) {
String url = urls[0];
String result = "";
HttpResponse response = doResponse(url);
if (response == null) {
return result;
} else {
try {
result = inputStreamToString(response.getEntity()
.getContent());
} catch (IllegalStateException e) {
Log.e(TAG, e.getLocalizedMessage(), e);
} catch (IOException e) {
Log.e(TAG, e.getLocalizedMessage(), e);
}
}
return result;
}
@Override
protected void onPostExecute(String response) {
handleResponse(response);
pDlg.dismiss();
}
public void handleResponse(String response) {
// try {
//
// JSONObject jArray = (JSONObject)JSONValue.parse(response);
// JSONObject jObj = jArray.getJSONObject("movieTransactional");
//
// for (int i = 0; i < jArray.length(); i++) { // **line 2**
// JSONObject childJSONObject = jArray.get(i);
// String name = childJSONObject.getString("name");
// int age = childJSONObject.getInt("age");
// }
try {
JSONObject jsonObj = new JSONObject(response);
JSONArray jsonArr;
jsonArr = jsonObj.getJSONArray("movieTransactional");
for (int i = 0; i < jsonArr.length(); i++) {
JSONObject obj = jsonArr.getJSONObject(i);
try {
int A1 = obj.getInt("a1");
System.out.println("A1 value : " + A1);
break;
} catch (JSONException ex) {
}
}
} catch (JSONException e) {
Log.e("SubCategorySelection", "Error parsing data "+e.toString());
}
}
// Establish connection and socket (data retrieval) timeouts
private HttpParams getHttpParams() {
HttpParams htpp = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(htpp, CONN_TIMEOUT);
HttpConnectionParams.setSoTimeout(htpp, SOCKET_TIMEOUT);
return htpp;
}
private HttpResponse doResponse(String url) {
// Use our connection and data timeouts as parameters for our
// DefaultHttpClient
HttpClient httpclient = new DefaultHttpClient(getHttpParams());
HttpResponse response = null;
try {
switch (taskType) {
case POST_TASK:
HttpPost httppost = new HttpPost(url);
// Add parameters
httppost.setEntity(new UrlEncodedFormEntity(params));
response = httpclient.execute(httppost);
break;
case GET_TASK:
HttpGet httpget = new HttpGet(url);
response = httpclient.execute(httpget);
break;
}
} catch (Exception e) {
Log.e(TAG, e.getLocalizedMessage(), e);
}
return response;
}
private String inputStreamToString(InputStream is) {
String line = "";
StringBuilder total = new StringBuilder();
// Wrap a BufferedReader around the InputStream
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
// Read response until the end
while ((line = rd.readLine()) != null) {
total.append(line);
}
} catch (IOException e) {
Log.e(TAG, e.getLocalizedMessage(), e);
}
// Return full string
return total.toString();
}
}