一个AsyncTask的内部HTTP请求 [英] HTTP Request inside an AsyncTask
本文介绍了一个AsyncTask的内部HTTP请求的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个解析XML文件的HTTP请求。
我试图从asyntask连接到互联网，但我一直没能
我做到这一点，作品把code线程里面，但不是一个AsycTask内
我的问题是，HTTP请求与该行code的字符串中调用：
字符串XML = parser.getXmlFromUrl（URL）;
运行此
公共字符串getXmlFromUrl（字符串URL）{
线程t =新的Thread（）{
公共无效的run（）{
XML = NULL;
尝试{
Log.i（LOG1，解析）;
// defaultHttpClient
DefaultHttpClient的HttpClient =新DefaultHttpClient（）;
HttpPost httpPost =新HttpPost（http://api.androidhive.info/music/music.xml）; HTT presponse HTT presponse = httpClient.execute（httpPost）;
HttpEntity httpEntity = HTT presponse.getEntity（）;
XML = EntityUtils.toString（httpEntity）; }赶上（UnsupportedEncodingException五）{
e.printStackTrace（）;
}赶上（ClientProtocolException E）{
e.printStackTrace（）;
}赶上（IOException异常五）{
e.printStackTrace（）;
}
mHandler.post（mUpdateResults）;
}
};
t.start（）;
返回XML;
} 最终的Runnable mUpdateResults =新的Runnable（）{
公共无效的run（）{// 2 }
};
正如我提到的那样，HTTP请求是在一个线程中，但我总能找到错误，当我试图把它里面AsycTask ......我不知道该怎么做。
我已经提到AsycTask的资料，看了很多次，我已搜查教程，但我不能正确地建立它。
两天后，我开始有点绝望
我把完整的code对我的工作，如果有人能告诉我如何更换AsyncTask的线索，我会很感激。
非常感谢你和问候
的充分的活动：的
公共类PruebasActivity延伸活动{
静态最终字符串URL =http://api.androidhive.info/music/music.xml;
// XML节点键
静态最后弦乐KEY_SONG =歌; //父节点
静态最后弦乐KEY_ID =ID;
静态最后弦乐KEY_TITLE =称号;
静态最后弦乐KEY_ARTIST =艺术家;
静态最后弦乐KEY_DURATION =时间;
静态最后弦乐KEY_THUMB_URL =thumb_url; 私人的ArrayList＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;数据;
ArrayList的＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT; songsList; ListView控件列表;
LazyAdapter适配器;
XML字符串; 最后的处理程序mHandler =新的处理程序（）;
//构造
公共无效XMLParser的（）{ } / **
* Cogiendo埃尔XML德拉URL mediante HTTP请求
* @参数的URL字符串
* * /
公共字符串getXmlFromUrl（字符串URL）{
线程t =新的Thread（）{
公共无效的run（）{
XML = NULL;
尝试{
Log.i（LOG1，解析）;
// defaultHttpClient
DefaultHttpClient的HttpClient =新DefaultHttpClient（）;
HttpPost httpPost =新HttpPost（http://api.androidhive.info/music/music.xml）; HTT presponse HTT presponse = httpClient.execute（httpPost）;
HttpEntity httpEntity = HTT presponse.getEntity（）;
XML = EntityUtils.toString（httpEntity）; }赶上（UnsupportedEncodingException五）{
e.printStackTrace（）;
}赶上（ClientProtocolException E）{
e.printStackTrace（）;
}赶上（IOException异常五）{
e.printStackTrace（）;
}
mHandler.post（mUpdateResults）;
}
};
t.start（）;
返回XML;
} 最终的Runnable mUpdateResults =新的Runnable（）{
公共无效的run（）{// 2 }
}; / *
* @参数XML字符串
* * /
公开文件getDomElement（字符串XML）{
文档DOC = NULL;
DBF的DocumentBuilderFactory = DocumentBuilderFactory.newInstance（）;
尝试{ 的DocumentBuilder分贝= dbf.newDocumentBuilder（）; InputSource的是=新的InputSource（）;
is.setCharacterStream（新StringReader（XML））;
DOC = db.parse（是）; }赶上（的ParserConfigurationException E）{
Log.e（错误，e.getMessage（））;
返回null;
}赶上（SAXException的E）{
Log.e（错误，e.getMessage（））;
返回null;
}赶上（IOException异常五）{
Log.e（错误，e.getMessage（））;
返回null;
} 返回文档;
} / *
* @参数ELEM元素
* /
公共最后弦乐getElementValue（节点ELEM）{
子节点;
如果（ELEM！= NULL）{
如果（elem.hasChildNodes（））{
对于（孩子= elem.getFirstChild（！）;孩子= NULL;孩子= child.getNextSibling（））{
如果（child.getNodeType（）== Node.TEXT_NODE）{
返回child.getNodeValue（）;
}
}
}
}
返回;
} / *
* @参数Element节点
* @参数密钥字符串
* * /
公共字符串的getValue（元素项，字符串str）{
节点列表N = item.getElementsByTagName（STR）;
返回this.getElementValue（n.item（0））;
} @覆盖
公共无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.main）; 名单=（ListView控件）findViewById（R.id.list）; songsList =新的ArrayList＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;（）; XMLParser的解析器=新XMLParser的（）;
字符串XML = parser.getXmlFromUrl（URL）; // Cogiendo XML德拉网址
文档的文档= parser.getDomElement（XML）; // Cogiendo DOM德洛斯elementos 节点列表NL = doc.getElementsByTagName（KEY_SONG）;
//遍历所有歌曲节点＆LT循环;宋＆GT;
的for（int i = 0; I＆LT; nl.getLength（）;我++）{
//创建新的HashMap
HashMap的＆LT;字符串，字符串＆GT;地图=新的HashMap＆LT;字符串，字符串＆GT;（）;
元素e =（元）nl.item（I）
//将每个子节点的HashMap键=＆GT;值
map.put（KEY_ID，parser.getValue（即KEY_ID））;
map.put（KEY_TITLE，parser.getValue（即KEY_TITLE））;
map.put（KEY_ARTIST，parser.getValue（即KEY_ARTIST））;
map.put（KEY_DURATION，parser.getValue（即KEY_DURATION））;
map.put（KEY_THUMB_URL，parser.getValue（即KEY_THUMB_URL））; //添加HashList到ArrayList的
songsList.add（地图）;
} // Pasando DATOS parseados德尔adaptador人的ArrayList
适配器=新MinAdapter（这一点，songsList）;
list.setAdapter（适配器）;
}
}
解决方案
HTTP请求可以的AsyncTask的doInBackground函数运行，您可运行是onPostExecute功能。
结果是这样的：
公共类XmlTask扩展的AsyncTask＆LT;弦乐，太虚，字符串＆GT; { 公共字符串doInBackground（字符串的URL ...）{
字符串URL =网址[0]; //此处将您getXmlFromUrl内容 返回XML;
} 公共无效onPostExecute（字符串XML）{
//你的XML解析staement这里
}
}
在此code，螺纹和可运行的都是不必要的。
而在你活动只需轻按：
新XmlTask（）执行（HTTP：// yourURL的）;
I have an HTTP Request that parses an XML file. I'm trying to connect to internet from an asyntask but I have not been able
I do this and works by putting the code inside a thread, but not inside an AsycTask The problem I have is that the HTTP Request is called within a String with this line of code:
String xml = parser.getXmlFromUrl(URL);
Running this
public String getXmlFromUrl(String url) {
Thread t= new Thread(){
public void run() {
xml = null;
try {
Log.i("Log1","Parse");
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost("http://api.androidhive.info/music/music.xml");
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
xml = EntityUtils.toString(httpEntity);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
mHandler.post(mUpdateResults);
}
};
t.start();
return xml;
}
final Runnable mUpdateResults =new Runnable (){
public void run(){//2
}
};
As I mentioned, the HTTP Request is within a thread, but I always find errors when I try to put it inside a AsycTask ... I do not know how do it.
I have been referred to the documentation of AsycTask and have read many times, I have searched tutorials, but I could not build it correctly.
After two days, i begin to be a little desperate
I put the complete code for my work, if anyone can tell me how to replace a AsyncTask thread, I'll be very grateful.
Thank you very much and regards
full activity:
public class PruebasActivity extends Activity {
static final String URL = "http://api.androidhive.info/music/music.xml";
// XML node keys
static final String KEY_SONG = "song"; // parent node
static final String KEY_ID = "id";
static final String KEY_TITLE = "title";
static final String KEY_ARTIST = "artist";
static final String KEY_DURATION = "duration";
static final String KEY_THUMB_URL = "thumb_url";
private ArrayList<HashMap<String, String>> data;
ArrayList<HashMap<String, String>> songsList;
ListView list;
LazyAdapter adapter;
String xml;
final Handler mHandler=new Handler();
// constructor
public void XMLParser() {
}
/**
* Cogiendo el XML de la URL mediante HTTP request
* @param url string
* */
public String getXmlFromUrl(String url) {
Thread t= new Thread(){
public void run() {
xml = null;
try {
Log.i("Log1","Parse");
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost("http://api.androidhive.info/music/music.xml");
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
xml = EntityUtils.toString(httpEntity);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
mHandler.post(mUpdateResults);
}
};
t.start();
return xml;
}
final Runnable mUpdateResults =new Runnable (){
public void run(){//2
}
};
/*
* @param XML string
* */
public Document getDomElement(String xml){
Document doc = null;
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder db = dbf.newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader(xml));
doc = db.parse(is);
} catch (ParserConfigurationException e) {
Log.e("Error: ", e.getMessage());
return null;
} catch (SAXException e) {
Log.e("Error: ", e.getMessage());
return null;
} catch (IOException e) {
Log.e("Error: ", e.getMessage());
return null;
}
return doc;
}
/*
* @param elem element
*/
public final String getElementValue( Node elem ) {
Node child;
if( elem != null){
if (elem.hasChildNodes()){
for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
if( child.getNodeType() == Node.TEXT_NODE ){
return child.getNodeValue();
}
}
}
}
return "";
}
/*
* @param Element node
* @param key string
* */
public String getValue(Element item, String str) {
NodeList n = item.getElementsByTagName(str);
return this.getElementValue(n.item(0));
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
list=(ListView)findViewById(R.id.list);
songsList = new ArrayList<HashMap<String, String>>();
XMLParser parser = new XMLParser();
String xml = parser.getXmlFromUrl(URL); // Cogiendo XML de la URL
Document doc = parser.getDomElement(xml); // Cogiendo DOM de los elementos
NodeList nl = doc.getElementsByTagName(KEY_SONG);
// looping through all song nodes <song>
for (int i = 0; i < nl.getLength(); i++) {
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
Element e = (Element) nl.item(i);
// adding each child node to HashMap key => value
map.put(KEY_ID, parser.getValue(e, KEY_ID));
map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST));
map.put(KEY_DURATION, parser.getValue(e, KEY_DURATION));
map.put(KEY_THUMB_URL, parser.getValue(e, KEY_THUMB_URL));
// adding HashList to ArrayList
songsList.add(map);
}
// Pasando datos parseados del adaptador al arrayList
adapter=new MinAdapter(this, songsList);
list.setAdapter(adapter);
}
}
解决方案
The HTTP request can be run in the doInBackground function of Asynctask and your runnable is the onPostExecute function. The result is this :
public class XmlTask extends AsyncTask<String, Void, String>{
public String doInBackground(String... urls){
String url = urls[0];
// Place your getXmlFromUrl content here
return xml;
}
public void onPostExecute(String xml){
// Your XML parsing staement here
}
}
In this code, Thread and runnable are unnecessary.
And in your activity just tap:
new XmlTask().execute("http://yoururl");
这篇关于一个AsyncTask的内部HTTP请求的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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