【安卓】解析XML格式数据

  这里需要搭建一个Web服务器，在这个服务器上提供一段XML文本，然后在程序里去访问这个服务器，再对得到的XML文本进行解析。首先需要下载一个Apache服务器的安装包，官方下载地址是：http://httpd.apache.org。然后一直点击“Next”，会提示让你输入自己的域名，我们随便填一个域名就可以了。之后继续点击“Next”就可以完成安装了，安装成功后服务器会自动启动。接下来进入安装位置的htdocs目录下，在这里新建一个名为get_data.xml的文件，然后编辑这个文件，并加入如下XML格式的内容。

<apps><app><id>1</id><name>Google Maps</name><version>1.0</version></app><app><id>2</id><name>Chrome</name><version>2.1</version></app><app><id>3</id><name>Google Play</name><version>2.3</version></app>
</apps>

  这时在浏览器中访问http://127.0.0.1/get_data.xml这个网址访问到。

Pull解析方式

  修改MainActivity中的代码。

public class MainActivity extends AppCompatActivity implements View.OnClickListener {TextView responseText;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Button sendRequest = (Button) findViewById(R.id.sendRequestBtn);responseText = (TextView) findViewById(R.id.responseText);sendRequest.setOnClickListener(this);}@Overridepublic void onClick(View v) {if (v.getId() == R.id.sendRequestBtn) {
//            sendRequestWithHttpURLConnection();sendRequestWithOkHttp();}}private void sendRequestWithOkHttp() {new Thread(new Runnable() {@Overridepublic void run() {try {OkHttpClient client = new OkHttpClient();Request request = new Request.Builder()
//                            .url("https://www.baidu.com").url("http://10.0.2.2/get_data.xml").build();Response response = client.newCall(request).execute();String responseData = response.body().string();
//                    showResponse(responseData);parseXMLWithPull(responseData);} catch (Exception e) {e.printStackTrace();}}}).start();}private void parseXMLWithPull(String xmlData) {try {XmlPullParserFactory factory = XmlPullParserFactory.newInstance();XmlPullParser xmlPullParser = factory.newPullParser();xmlPullParser.setInput(new StringReader(xmlData));int eventType = xmlPullParser.getEventType();String id = "";String name = "";String version = "";while (eventType != XmlPullParser.END_DOCUMENT) {String nodeName = xmlPullParser.getName();switch (eventType) {// 开始解析某个节点case XmlPullParser.START_TAG: {if ("id".equals(nodeName)) {id = xmlPullParser.nextText();} else if ("name".equals(nodeName)) {version = xmlPullParser.nextText();}break;}// 完成解析某个节点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;}eventType = xmlPullParser.next();}} catch (Exception e) {e.printStackTrace();}}private void sendRequestWithHttpURLConnection() {// 开启线程来发起网络请求new Thread(new Runnable() {@Overridepublic void run() {HttpURLConnection connection = null;BufferedReader reader = null;try {URL url = new URL("https://www.baidu.com");connection = (HttpURLConnection) url.openConnection();connection.setRequestMethod("GET");connection.setConnectTimeout(8000);connection.setReadTimeout(8000);InputStream in = connection.getInputStream();// 下面对获取到的输入流进行读取reader = new BufferedReader(new InputStreamReader(in));StringBuilder response = new StringBuilder();String line;while ((line = reader.readLine()) != null) {response.append(line);}showResponse(response.toString());} catch (Exception e) {e.printStackTrace();} finally {if (reader != null) {try {reader.close();} catch (IOException e) {e.printStackTrace();}}if (connection != null) {connection.disconnect();}}}}).start();}private void showResponse(final String response) {runOnUiThread(new Runnable() {@Overridepublic void run() {// 在这里进行UI操作，将结果显示到界面上responseText.setText(response);}});}
}

  将HTTP请求的地址改成了http://10.0.2.2/get_data.xml，10.0.2.2对于模拟器来说就是计算机本机的IP地址。在得到了服务器返回的数据后，调用parseXMLWithPull()方法来解析服务器返回的数据。

  从Android9.0系统开始，应用程序默认只允许使用HTTPS类型的网络请求，HTTP类型的网络请求因为有安全隐患默认不再被支持，而Apache服务器现在使用的就是HTTP。

  为了能让程序使用HTTP需要进行配置。右击res目录→New→Directory，创建一个xml目录，接着右击xml目录→New→File，创建一个network_config.xml文件。然后修改network_config.xml文件中的内容。

<?xml version="1.0" encoding="utf-8"?>
<network-security-config><base-config cleartextTrafficPermitted="true"><trust-anchors><certificates src="system" /></trust-anchors></base-config>
</network-security-config>

  这段配置文件的意思就是允许我们以明文的方式在网络上传输数据，而HTTP使用的就是明文传输方式。

  接下来修改AndroidManifest.xml中的代码来启用我们刚才创建的配置文件。

<manifest xmlns:android="http://schemas.android.com/apk/res/android"package="com.example.networktest">...<applicationandroid:allowBackup="true"android:icon="@mipmap/ic_launcher"android:label="@string/app_name"android:roundIcon="@mipmap/ic_launcher_round"android:supportsRtl="true"android:theme="@style/AppTheme"android:networkSecurityConfig="@xml/network_config">...</application>
</manifest>

  这样就可以在程序中使用HTTP了。

SAX解析方式

  新建一个ContentHandler类继承自DefaultHandler，并重写父类的5个方法。

public class ContentHandler extends DefaultHandler {private String nodeName;private StringBuilder id;private StringBuilder name;private StringBuilder version;@Overridepublic void startDocument() throws SAXException {id = new StringBuilder();name = new StringBuilder();version = new StringBuilder();}@Overridepublic void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {// 记录当前节点名nodeName = localName;}@Overridepublic void characters(char[] ch, int start, int length) throws  SAXException {// 根据当前的节点名判断将内容添加到哪一个StringBuilder对象中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);}}@Overridepublic void endElement(String uri, String localName, String qName) throws SAXException {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);}}@Overridepublic void endDocument() throws SAXException {super.endDocument();}
}

  修改MainActivity中的代码。

	private void sendRequestWithOkHttp() {new Thread(new Runnable() {@Overridepublic void run() {try {OkHttpClient client = new OkHttpClient();Request request = new Request.Builder()
//                            .url("https://www.baidu.com").url("http://10.0.2.2/get_data.xml").build();Response response = client.newCall(request).execute();String responseData = response.body().string();
//                    showResponse(responseData);
//                    parseXMLWithPull(responseData);parseXMLWithSAX(responseData);} catch (Exception e) {e.printStackTrace();}}}).start();}private void parseXMLWithSAX(String xmlData) {try {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)));} catch (Exception e) {e.printStackTrace();}}