检查服务器上是不是存在 URL
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【中文标题】检查服务器上是不是存在 URL【英文标题】：Check if URL exists or not on Server检查服务器上是否存在 URL 【发布时间】：2014-12-12 15:38:06 【问题描述】：这是我用来验证 URL 是否存在于服务器上的代码，但总是不存在但链接仍然存在
我在代码中出错的地方，为什么我总是得到“不存在！”
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";
boolean bResponse = exists(customURL);
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();
public static boolean exists(String URLName)
try
HttpURLConnection.setFollowRedirects(false);
HttpURLConnection con = (HttpURLConnection) new URL(URLName).openConnection();
con.setRequestMethod("HEAD");
return (con.getResponseCode() == HttpURLConnection.HTTP_OK);
catch (Exception e)
e.printStackTrace();
return false;
【问题讨论】：
***.com/questions/1378199/… @NaveenTamrakar 尝试仍然得到“不存在！” 在exist function HttpURLConnection.setFollowRedirects(false)中去掉这个； 只需添加con.connect() about return 声明..
@ashutiwari4 尚未完成
【参考方案1】：
你会得到Network On Main Thread Exception
看NetworkOnMainThreadException
所以你的方法总是返回 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();
使用 ScheduledThreadPoolExecutor：
但记得关闭它！
public class MainActivity extends Activity
String customURL;
String msg = "";
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
customURL = "http://www.desicomments.com/dc3/08/273858/273858.jpg";
final ScheduledThreadPoolExecutor myTimer = new ScheduledThreadPoolExecutor(1);
myTimer.scheduleAtFixedRate(new Runnable()
@Override
public void run()
try
HttpURLConnection.setFollowRedirects(false);
HttpURLConnection con = (HttpURLConnection) new URL(customURL).openConnection();
con.setRequestMethod("HEAD");
System.out.println(con.getResponseCode());
if(con.getResponseCode() == HttpURLConnection.HTTP_OK)
msg = "File exist!";
else
msg = "File does not exist!";
runOnUiThread(new Runnable()
@Override
public void run()
Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
);
catch (Exception e)
e.printStackTrace();
return;
, 0,10000, TimeUnit.MILLISECONDS);
【讨论】：
非常感谢你能帮我对现有代码做一个小的修改吗，因为我必须每 10 秒检查一次这个链接，所以你能对此进行更改 该任务的编写器计时器。每次@Sophie 都会调用这个 asytask 我想检查一次。有替代品吗？ 似乎它只适用于图像或 Mp3 等文件 url。我正在尝试https://app.box.com/s/w6quybg71ngjhetflz77，但没有工作说链接不存在【参考方案2】：
把你的exists()改成这个
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;
【讨论】：
你应该总是使用 AsynckTask【参考方案3】：使用if(bResponse) 代替if(bResponse==true)
【讨论】：
【参考方案4】：你可以使用下面的代码来试试。
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,
如果这样做，将会出现异常并且您无法获得正确的结果。 因此，如果您希望应用程序执行网络操作，您可以使用另一个线程来执行它。
【讨论】：
【参考方案5】：我使用此代码来验证 url 是否有效。我已经用图片网址测试了这段代码
例子：
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());
【讨论】：
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