Android——SAX方式決議XML資料

XML檔案建立已經Apache服務器建立已經在上一篇介紹過，此處不再多過闡述
正文：
添加jar包

implementation 'com.squareup.okhttp3:okhttp:3.4.1'

閉包里申請網路權限

<uses-permission android:name="android.permission.INTERNET"/>

布局檔案中就一個Button，此處不再闡述，決議的XML資料將以日志方式體現
建立一個ContentHandler類并繼承DefaultHandler類，并重寫父類的5個方法
ContentHandler.java代碼如下：

public class ContentHandler extends DefaultHandler {
    private String nodeName;
    private StringBuilder id;
    private StringBuilder name;
    private StringBuilder version;
    //開始決議XML檔案
    @Override
    public void startDocument() throws SAXException {
        super.startDocument();
        id = new StringBuilder();
        name = new StringBuilder();
        version = new StringBuilder();
    }
    //開始決議某個節點
    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        super.startElement(uri, localName, qName, attributes);
        nodeName = localName;
    }
   //獲取某個節點的內容
    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        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);
        }
    }
  //完成某個節點決議
    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        super.endElement(uri, localName, qName);
        if ("app".equals(nodeName)) {
            Log.d("ID = ", id.toString().trim());
            Log.d("Name = ", name.toString().trim());
            Log.d("Version = ", version.toString().trim());
            //清空StringBuilder
            id.setLength(0);
            name.setLength(0);
            version.setLength(0);
        }
    }
  //完成整個XML檔案決議
    @Override
    public void endDocument() throws SAXException {
        super.endDocument();
    }
}

MainActivity.java代碼如下：

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private Button SendRequest;
    private TextView ResponseText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        SendRequest = (Button) findViewById(R.id.SendRequest);
        ResponseText = (TextView)findViewById(R.id.Response);
        SendRequest.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
      if (v.getId() == R.id.SendRequest){
          SendRequestToOkhttp();
      }
    }
    private void SendRequestToOkhttp() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    OkHttpClient Client = new OkHttpClient();
                    //本機ip地址
                    Request request = new Request.Builder().url("http://192.168.0.60:8888/data.xml").build();//發送請求
                    Response response = Client.newCall(request).execute();//發送請求并獲取服務器回傳的資料
                    String ResponseData = response.body().string();//獲取具體資料
                    ParseXMLWithSAX(ResponseData);//顯示資料
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
    private void ParseXMLWithSAX(String XMLData){
        try{
            SAXParserFactory factory = SAXParserFactory.newInstance();//獲取SAXParserFactory實體
            XMLReader xmlReader = factory.newSAXParser().getXMLReader();
            ContentHandler handler = new ContentHandler();
            xmlReader.setContentHandler(handler);
            //開始決議
            xmlReader.parse(new InputSource(new StringReader(XMLData)));
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}