我正在创建一个 Android 应用程序，而且我对线程处理还比较陌生，我有两种不同的方法用于调用两个不同的 Web 服务，如下所示，那么如何更改这些方法以使用 AsyncTask 在后台运行线程？
我的代码:
public List<String> getEvacRouteNames(){
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
BufferedReader in = null;
String page;
try {
HttpClient client = new DefaultHttpClient();
HttpPost request = new HttpPost();
request.setURI(URI)
//Add The parameters. The asmx webservice requires a double but gets posted as a string in a text field
List<NameValuePair> nameValPairs = new ArrayList<NameValuePair>(0);
request.setEntity(new UrlEncodedFormEntity(nameValPairs));
HttpResponse response = client.execute(request);
in = new BufferedReader
(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null) {
sb.append(line + NL);
}
in.close();
page = sb.toString();
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(new InputSource(new StringReader(page)));
// normalize the document
doc.getDocumentElement().normalize();
// get the root node
NodeList nodeList = doc.getElementsByTagName("string");
// the node has three child nodes
for (int n = 0; n < nodeList.getLength(); n++) {
Node node=nodeList.item(n);
String upperNode = node.getNodeName();
Node temp=node.getChildNodes().item(n);
if (upperNode.equals("string")){
String routeName = node.getTextContent();
routeNamesList.add(node.getTextContent());
}
}
//System.out.println(page);
} catch (Exception E) {
E.printStackTrace();
}
finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return routeNamesList;
}
public EvacRoute getEvacuationRoute(String routeName, LatLng currentLocation, String lat, String lon) throws URISyntaxException, ClientProtocolException, IOException, ParserConfigurationException, SAXException{
evacRouteList = new ArrayList<EvacRoute>();
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
EvacRoute evacRoute = new EvacRoute();
evacRoute.setDestinationName(routeName);
BufferedReader in = null;
String page;
latslngsList = new ArrayList<LatLng>();
try {
latslngsList.add(currentLocation);
HttpClient client = new DefaultHttpClient();
HttpPost request = new HttpPost();
request.setURI(URI)
//Add The parameters. The asmx webservice requires a double but gets posted as a string in a text field
List<NameValuePair> nameValPairs = new ArrayList<NameValuePair>(2);
nameValPairs.add(new BasicNameValuePair("Route_Name", routeName));
nameValPairs.add(new BasicNameValuePair("In_Lat", lat));
nameValPairs.add(new BasicNameValuePair("In_Lon", lon));
request.setEntity(new UrlEncodedFormEntity(nameValPairs));
HttpResponse response = client.execute(request);
in = new BufferedReader
(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null) {
sb.append(line + NL);
}
in.close();
page = sb.toString();
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(new InputSource(new StringReader(page)));
// normalize the document
doc.getDocumentElement().normalize();
// get the root node
NodeList nodeList = doc.getElementsByTagName("simple_ll_waypoint");
double latitude = 0;
double longitude= 0;
// the node has three child nodes
for (int n = 0; n < nodeList.getLength(); n++) {
String latString = "";
String longString = "";
Node node=nodeList.item(n);
String upperNode = node.getNodeName();
StringBuilder addressStrBlder = new StringBuilder();
for (int i = 0; i < node.getChildNodes().getLength(); i++) {
Node temp=node.getChildNodes().item(i);
String nodeName = temp.getNodeName();
String nodevalue = temp.getNodeValue();
if(temp.getNodeName().equalsIgnoreCase("Lat")){
latString = temp.getTextContent();
latitude = Double.parseDouble(latString);
} else if(temp.getNodeName().equalsIgnoreCase("Lon")){
longString = temp.getTextContent();
longitude = Double.parseDouble(longString);
LatLng latlng = new LatLng(latitude, longitude);
latslngsList.add(latlng);
}
}
//Log.e("Fuel Stop", fuelStop.toString());
}
//System.out.println(page);
} catch (Exception E) {
E.printStackTrace();
}
finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
evacRoute.setLatLngList(latslngsList);
evacRouteList.add(evacRoute);
return evacRoute;
}
最佳答案
您可以从 AsyncTask 扩展您的类，并执行以下操作:
public class AsyncCustomTask extends AsyncTask<Void, Void, List<String>> {
@Override
protected List<String> doInBackground(Void... params) {
return getEvacRouteNames();
}
@Override
protected void onPostExecute(List<String> result) {
// Function finished and value has returned.
}
}
并调用它:
new AsyncCustomTask().execute();
更新了第二个问题
对于有参数的方法，您可以使用类的构造函数，例如:
public class AsyncSecondCustomTask extends AsyncTask<Void, Void, EvacRoute> {
private final String routeName;
private final LatLng currentLocation;
private final String lat;
private final String lon;
public AsyncSecondCustomTask(String routeName, LatLng currentLocation, String lat, String lon) {
this.routeName = routeName;
this.currentLocation = currentLocation;
this.lat = lat;
this.lon = lon;
}
@Override
protected EvacRoute doInBackground(Void... params) {
return getEvacuationRoute(routeName, currentLocation, lat, lon);
}
@Override
protected void onPostExecute(EvacRoute result) {
// Function finished and value has returned.
}
}
你可以这样调用它:
new AsyncSecondCustomTask("", null, "", "").execute();
关于java - 如何向其中添加 AsyncTask？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16577700/