问题描述

android 中 AsyncTask的使用

我使用AsnycTask 来连接URL ，解析和返回 xml：

class Connecting extends AsyncTask<String, String, String> {
    private String URLPath = "";
    private HttpURLConnection Connection;
    private InputStream InputStream;
    private boolean Return1 = false;
    private int Return2 = -1;

    public Connecting (String fn, String u) {
        FileName = fn;
    URLPath = u;
        Connection = null;
    InputStream = null;

    Return1 = false;
    Return2 = -1;

    execute();
    }

    public boolean getReturn1() {
    return Return1;
    }

    public int getReturn2() {
    return Return2;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected String doInBackground(String... aurl) {
        try {
            URL url = new URL(URLPath);
            Connection = (HttpURLConnection)url.openConnection();
            Connection.setConnectTimeout(10000);
            Connection.setReadTimeout(10000);
            Connection.setDoInput(true);
            Connection.setUseCaches(false);
            Connection.connect();
            InputStream = Connection.getInputStream();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(String unused) {
        super.onPostExecute(unused);

        try {
            InputStreamReader fsr = new InputStreamReader(InputStream);

            BufferedReader br = new BufferedReader(fsr);
            String line = "";
            while((line = br.readLine()) != null) {
                //parse Reture1 and Return2
            }
        }
        catch(Exception e) {
            e.printStackTrace();
        }
        Connection = null;
    }
}

我使用下面的代码来调用：

Connecting con = new Connecting(Name, URL);
System.out.println("Return1 " + con.getReturn1());
System.out.println("Return2 " + con.getReturn2());

返回 false 和 int 值 -1。
打印消息后连接 URL。
我想获取 value 值，这个值是连接成功的，并且时从 xml 中解析的，如何实现？

解决方案

可以写构造方法也可以不写构造方法，不写如下,外部调用new Connecting().execute(String fileName,String urlPath );

class Connecting extends AsyncTask<String, Integer, Integer> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            //do something before parse XML
        }

        @Override
        protected Integer doInBackground(String... params) {
            String fileName = params[0];
            String urlPath = params[1];
            //parse XML
            return -1;
        }

        @Override
        protected void onPostExecute(Integer result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            // result即返回值
        }

    }

有构造方法的只需在里面加入
private String fileName;
private String urlPath;
public Connecting(String fileName,String urlPath) {
this.fileName = fileName;
this.urlPath = urlPath;
}