解析XML前下載檔案

參考Mars的方式為了要下載檔案，獨立寫了一個類別HttpDownloader.java 方便以後的引用

避免不必要的重複代碼

HttpDownloader.java

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public class HttpDownloader {
    private URL myurl=null;
    public String download(String urlstr){
    StringBuffer sb=new StringBuffer();
    String line=null;
    BufferedReader buffer= null;
    try {

        myurl = new URL(urlstr);
        HttpsURLConnection con= (HttpsURLConnection) myurl.openConnection();
        con.connect();
        buffer=new BufferedReader(new InputStreamReader(con.getInputStream()));
            while ((line=buffer.readLine())!=null) {
            //sb.append(line);
            sb.append(line);

            //System.out.println("testest");
            //System.out.println(sb.toString());
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally{
            try {
                buffer.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    return sb.toString();

    }
}

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然後要使用時，在MainActivity.java使用

MainActivity.java

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public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_main);
        Button btGetxml=(Button)findViewById(R.id.button1);
        btGetxml.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {

                TextView tv1=(TextView)findViewById(R.id.tv1);
                HttpDownloader httpDownloader=new HttpDownloader();
                String getxml=httpDownloader.download("https://weather.yahooapis.com/forecastrss?w=2306179");
                System.out.println(getxml);
                //tv1.setText(getxml);
                try {
                    //使用DOM解析XML
                    DocumentBuilderFactory dfactory=DocumentBuilderFactory.newInstance();
                    DocumentBuilder builder = dfactory.newDocumentBuilder();
                    Document doc = builder.parse(new InputSource(new StringReader(getxml)));
                      //

以下省略