Android 检查服务器上是否存在URL

这是我的代码，我用它来验证，URL是否存在于服务器上，但总是不存在，但链接是活动的

我在代码中犯了错误，为什么我总是得到“不存在！”

将您的exists（）更改为此

public boolean exists(String url){
    HttpURLConnection huc =  ( HttpURLConnection )  url.openConnection (); 
    huc.setRequestMethod ("GET");  //OR  huc.setRequestMethod ("HEAD"); 
    huc.connect () ; 
    int code = huc.getResponseCode() ;
    System.out.println(code);

     if(code==200)
       return true;
     else
    return false;
   }

---

您将在主线程上获得

网络异常

看

因此，您的方法总是返回false，因为：

   catch (Exception e) {
        e.printStackTrace();
        return false;
    }

快速修复：

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);     

        String customURL = "http://www.desicomments.com/dc3/08/273858/273858.jpg";

        MyTask task = new MyTask();
        task.execute(customURL);
    }


    private class MyTask extends AsyncTask<String, Void, Boolean> {

        @Override
        protected void onPreExecute() {

        }

        @Override
        protected Boolean doInBackground(String... params) {

             try {
                    HttpURLConnection.setFollowRedirects(false);
                    HttpURLConnection con =  (HttpURLConnection) new URL(params[0]).openConnection();
                    con.setRequestMethod("HEAD");
                    System.out.println(con.getResponseCode()); 
                    return (con.getResponseCode() == HttpURLConnection.HTTP_OK);
                }
                catch (Exception e) {   
                    e.printStackTrace();    
                    return false;
                }
        }

        @Override
        protected void onPostExecute(Boolean result) {
            boolean bResponse = result;
             if (bResponse==true)
                {
                    Toast.makeText(MainActivity.this, "File exists!", Toast.LENGTH_SHORT).show();      
                }
                else
                {           
                    Toast.makeText(MainActivity.this, "File does not exist!", Toast.LENGTH_SHORT).show();
                }                  
        }           
    }
}

---

您可以使用以下代码进行尝试

    final String customURL = "http://www.desicomments.com/dc3/08/273858/273858.jpg";
            new Thread(){

                @Override
                public void run() {
                    // TODO Auto-generated method stub
                    super.run();
                    try {
                        URL url = new URL(customURL);
                        HttpURLConnection con = (HttpURLConnection) url.openConnection();
                        con.setRequestMethod("HEAD");
                        con.connect();
                        Log.i(TAG, "con.getResponseCode() IS : " + con.getResponseCode());
                        if(con.getResponseCode() == HttpURLConnection.HTTP_OK){
                            Log.i(TAG, "Sucess");
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                        Log.i(TAG, "fail");
                    }
                }

            }.start();

Reason: After android 2.3, you can't perform a networking operation on its main thread, 

如果您这样做，将出现can异常，您无法获得正确的结果。

---

因此，如果您希望应用程序执行联网操作，可以使用另一个线程来执行。

使用

if（breresponse）

而不是

if（breresponse==true）

我使用此代码验证url是否处于活动状态。我已经用图像url测试了这段代码

例如：

url = "https://ima.vn/wp-content/uploads/2017/11/ima-sofa-titan-trungkinh-1-of-3.jpg"
message = "Image url";

---

@Naveentamakar仍尝试获取“不存在！”删除存在函数HttpURLConnection中的此项。setFollowRedirects（false）；只需添加

con.connect（）

about

return

statement..@ashutiwari4还不知道您能为我对现有代码做一个小的修改吗？因为我必须每10秒钟检查一次这个链接，所以您能为该任务更改writer计时器吗。每次@SophieI想要检查一次，它都会将此任务称为asytask。有其他选择吗？似乎它只适用于文件url，如图像或Mp3等。我正在尝试

https://app.box.com/s/w6quybg71ngjhetflz77

但如果不使用它，则表示链接不存在您应该始终使用AsynckTask

    final String customURL = "http://www.desicomments.com/dc3/08/273858/273858.jpg";
            new Thread(){

                @Override
                public void run() {
                    // TODO Auto-generated method stub
                    super.run();
                    try {
                        URL url = new URL(customURL);
                        HttpURLConnection con = (HttpURLConnection) url.openConnection();
                        con.setRequestMethod("HEAD");
                        con.connect();
                        Log.i(TAG, "con.getResponseCode() IS : " + con.getResponseCode());
                        if(con.getResponseCode() == HttpURLConnection.HTTP_OK){
                            Log.i(TAG, "Sucess");
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                        Log.i(TAG, "fail");
                    }
                }

            }.start();

Reason: After android 2.3, you can't perform a networking operation on its main thread, 

url = "https://ima.vn/wp-content/uploads/2017/11/ima-sofa-titan-trungkinh-1-of-3.jpg"
message = "Image url";

public void assertUrlalive(String url, String message) {
    try {
        URL myUrl = new URL(url);
        HttpURLConnection huc = (HttpURLConnection) myUrl.openConnection();
        assertEquals(huc.getResponseCode(), 200, message);
    } catch (IOException e) {
        e.printStackTrace();
        logger.error("Connection Err: " + e.getMessage());
    }
}