安卓線程使用例子

   我也是剛剛接觸程序開發，一個菜鳥。前面和幾個同學準備做一個移動教務系統，網上看了很多資料都說了對運行一些費時。如數據庫、網絡的鏈接操作，需要新開一個thread對其進行處理。但是后面在對程序進行調試的過程中，剛開始的時候報了空指針錯誤。根據錯誤提示，進行修改。說實話，經過那個過程發現自己真的還很菜，排錯的經驗太少了。直到過了好久才想到報了空指針錯誤，是因為在線程里生成的對象，因為有時間延遲，對于線程后面的對象來說是空的，所以才導致了空指針錯誤。后面參考的解決方法是利用join()函數。當然也可用其他方法。

   下面寫的代碼：

public class MyThread extends Thread {
    private InputStream is = null;
    private String url;
    private String method;
    private List<NameValuePair> params;
    public MyThread(String url, String method, List<NameValuePair> params) {
        this.method = method;
        this.url = url;
        this.params = params;
    }
    public void run() {
        try {
            // check for request method
            if (method.equals("POST")) {
                // request method is POST
                // defaultHttpClient
                BasicHttpParams httpParameters = new BasicHttpParams();
                // Set the default socket timeout (SO_TIMEOUT)
                HttpConnectionParams
                        .setConnectionTimeout(httpParameters, 30000);
                // in milliseconds which is the timeout for waiting for
                // data.
                HttpConnectionParams.setSoTimeout(httpParameters, 30000);
                DefaultHttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(url);
                httpPost.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
                HttpResponse httpResponse = httpClient.execute(httpPost);
                HttpEntity httpEntity = httpResponse.getEntity();
                setIs(httpEntity.getContent());
            } else if (method.equals("GET")) {
                BasicHttpParams httpParameters = new BasicHttpParams();
                // Set the default socket timeout (SO_TIMEOUT)
                HttpConnectionParams
                        .setConnectionTimeout(httpParameters, 30000);
                // in milliseconds which is the timeout for waiting for
                // data.
                HttpConnectionParams.setSoTimeout(httpParameters, 30000);
                // request method is GET
                DefaultHttpClient httpClient = new DefaultHttpClient();
                String paramString = URLEncodedUtils.format(params, "utf-8");
                String temp_url = url + "?" + paramString;
                HttpGet httpGet = new HttpGet(temp_url);
                HttpResponse httpResponse = httpClient.execute(httpGet);
                HttpEntity httpEntity = httpResponse.getEntity();
                setIs(httpEntity.getContent());
            }
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public InputStream getIs() {
        return is;
    }
    public void setIs(InputStream is) {
        this.is = is;
    }
}

通過下面的語句對以上生成的對象（“setIs(httpEntity.getContent());“）進行調用

MyThread myThread = new MyThread(url, method, params);
myThread.start();
myThread.join();//同做join()函數對myThread進行處理，使其一般的對象那樣使用即可
is = myThread.getIs();//獲得is對象