Http的使用及XML和JSON数据解析

一、Handler及Messsage机制

1、handler用于处理消息，譬如更新UI，执行耗时任务等，主线程中执行耗时任务则需要开启新线程。Message则用来在主线程中发送消息，发送的消息会在message queen中，由looper分发给handler处理。

二、HttpURLConnection用来访问网络及文件IO流操作

1、HttpURLConnection建立起网络连接，进行基本设置，再取得流对象进行网络操作。获取方式如下

URL url = new URL("http://www.baidu.com");connection = (HttpURLConnection) url.openConnection();connection.setRequestMethod("GET");connection.setConnectTimeout(8000);connection.setReadTimeout(8000);InputStream in = connection.getInputStream();// InputStream in =url.openStream();

2、读取网络图片

URL url = new URL("http://192.168.1.100/yintao.jpg");// 手机访问本地服务器地址，使用本地IP地址// 打开该URL对应的资源的输入流InputStream is = url.openStream();// 从InputStream中解析出图片bitmap = BitmapFactory.decodeStream(is);is.close();

3、读取网络文本

URL url = new URL(<a target=_blank href="http://192.168.1.100/doc.txt">http://192.168.1.100/doc.txt);</a>InputStream is = url.openStream();BufferedReader reader = new BufferedReader(new InputStreamReader(is));String string;if ((string = reader.readLine()) != null) {stringBuilder = stringBuilder.append(string);}

4、存储网络数据到本地

URL url = new URL(<a target=_blank href="http://192.168.1.100/yintao.jpg">http://192.168.1.100/yintao.jpg</a>);InputStream is = url.openStream();// 打开手机文件对应的输出流OutputStream os = openFileOutput("crazyit.png",MODE_WORLD_READABLE);byte[] buff = new byte[1024];int hasRead = 0;// 将URL对应的资源下载到本地while ((hasRead = is.read(buff)) > 0) {os.write(buff, 0, hasRead);}is.close();os.close();

三、使用HttpClient

1、获取数据并发送数据

HttpClient httpClient = new DefaultHttpClient();HttpGet httpGet = new HttpGet("http://www.baidu.com");HttpResponse httpResponse = httpClient.execute(httpGet);if (httpResponse.getStatusLine().getStatusCode() == 200) {// 请求和响应都成功了HttpEntity entity = httpResponse.getEntity();String response = EntityUtils.toString(entity, "utf-8");<pre class="html" name="code">Message message = new Message();message.what = SHOW_RESPONSE;// 将服务器返回的结果存放到Message中message.obj = response.toString();handler.sendMessage(message);<pre class="html" name="code">}

四、解析数据

1、使用Pull解析XML

// 创建XML解析器工厂XmlPullParserFactory factory = XmlPullParserFactory.newInstance();// 得到XML PULL解析器XmlPullParser xmlPullParser = factory.newPullParser();// 传入XML数据xmlPullParser.setInput(new StringReader(xmlData));// 获取解析事件int eventType = xmlPullParser.getEventType();String id = "";String name = "";String version = "";while (eventType != XmlPullParser.END_DOCUMENT) {// 获取结点名字String nodeName = xmlPullParser.getName();switch (eventType) {// 开始解析某个结点case XmlPullParser.START_TAG: {if ("id".equals(nodeName)) {id = xmlPullParser.nextText();} else if ("name".equals(nodeName)) {name = xmlPullParser.nextText();} else if ("version".equals(nodeName)) {version = xmlPullParser.nextText();}break;}<pre class="html" name="code">// 完成解析某个结点case XmlPullParser.END_TAG: {if ("app".equals(nodeName)) {Log.d("MainActivity", "id is " + id);Log.d("MainActivity", "name is " + name);Log.d("MainActivity", "version is " + version);}break;}default:break;}// 解析下一结点eventType = xmlPullParser.next();

}

2、使用SAX解析XML

SAXParserFactory factory = SAXParserFactory.newInstance();XMLReader xmlReader = factory.newSAXParser().getXMLReader();ContentHandler handler = new ContentHandler();// 将ContentHandler的实例设置到XMLReader中xmlReader.setContentHandler(handler);// 开始执行解析xmlReader.parse(new InputSource(new StringReader(xmlData)));<pre class="html" name="code">//class ContentHandler extends DefaultHandler {private String nodeName;private StringBuilder id;private StringBuilder name;private StringBuilder version;public void startDocument() throws SAXException {// TODO Auto-generated method stubsuper.startDocument();id = new StringBuilder();name = new StringBuilder();version = new StringBuilder();}public void startElement(String uri, String localName, String qName,Attributes attributes) throws SAXException {// TODO Auto-generated method stub// super.startElement(uri, localName, qName, attributes);// 记录当前结点名nodeName = localName;}public void characters(char[] ch, int start, int length)throws SAXException {// TODO Auto-generated method stub// super.characters(ch, start, length);if ("id".equals(nodeName)) {id.append(ch, start, length);} else if ("name".equals(nodeName)) {name.append(ch, start, length);} else if ("version".equals(nodeName)) {version.append(ch, start, length);}}public void endElement(String uri, String localName, String qName)throws SAXException {// TODO Auto-generated method stub// super.endElement(uri, localName, qName);if ("app".equals(localName)) {Log.d("ContentHandler", "id is " + id.toString().trim());Log.d("ContentHandler", "name is " + name.toString().trim());Log.d("ContentHandler", "version is " + version.toString().trim());// 最后要将StringBuilder清空掉id.setLength(0);name.setLength(0);version.setLength(0);}}public void endDocument() throws SAXException {// TODO Auto-generated method stubsuper.endDocument();}}

3、使用JSONObject解析JSON

JSONArray jsonArray = new JSONArray(jsonData);for (int i = 0; i < jsonArray.length(); i++) {JSONObject jsonObject = jsonArray.getJSONObject(i);String id = jsonObject.getString("id");String name = jsonObject.getString("name");String version = jsonObject.getString("version");}

4，定义工具类实现http请求

interface HttpCallbackListener {void onFinish(String response);void onError(Exception e);}public class HttpUtil {/** * @param args */public static void sendHttpRequest(final String address,final HttpCallbackListener listener) {new Thread(new Runnable() {@Overridepublic void run() {HttpURLConnection connection = null;try {URL url = new URL(address);connection = (HttpURLConnection) url.openConnection();connection.setRequestMethod("GET");connection.setConnectTimeout(8000);connection.setReadTimeout(8000);connection.setDoInput(true);connection.setDoOutput(true);InputStream in = connection.getInputStream();BufferedReader reader = new BufferedReader(new InputStreamReader(in));StringBuilder response = new StringBuilder();String line;while ((line = reader.readLine()) != null) {response.append(line);}if (listener != null) {// 回调onFinish()方法listener.onFinish(response.toString());}} catch (Exception e) {if (listener != null) {// 回调onError()方法listener.onError(e);}} finally {if (connection != null) {connection.disconnect();}}}}).start();}}