我可以设置默认的全局Java套接字超时吗？

Question

I am running into a problem where various places in my application involving http and ftp connections are hanging indefinitely (observed for hours at a time before killing the java process) on java.net.SocketInputStream.socketRead0.

I'd like to override the default socket timeout of 0 globally so that I don't have to set it in every single location where I initiate a connection. Is there some global Java property or method I can call to set the default socket timeout to something other than 0?

Answer 1

It depends on how your application creates sockets. If your application code uses URLConnection then you can set default timeout using JVM properties:

-Dsun.net.client.defaultReadTimeout=30000
-Dsun.net.client.defaultConnectTimeout=5000

This properties are implementation specific but still works for latest Oracle/OpenJDK.

https://docs.oracle.com/javase/8/docs/technotes/guides/net/properties.html

Answer 2

It depends upon how you wrote the code. From my perspective, you should have created an APIClient which takes care of making the http/ftp calls and returns the response to the caller function. That is, every http/ftp call has to go through this APIClient file. Its good to have a class parameter/constant which stores the timeout in ms and then use this constant as timeout while making a http/ftp call.

public abstract class WebServiceAPIClient {
    protected String authUser;
    protected String authPassword;
    // Set the connection timeout whatever you want...
    final Integer connectionTimeOut = 60000;

    public WebServiceAPIClient(String user, String pwd, int errorCode) {
        this.authUser = user;
        this.authPassword = pwd;
        this.errorIdentiferCode = errorCode;
    }

    public String requestRESTGet(String url, List<Integer> successCodes, boolean addBasicAuth) throws CloudWebServiceInvocationException {
    Long start = System.currentTimeMillis();
    HttpGet get = new HttpGet(url);
    DefaultHttpClient client = getHttpClient();
    try {
        if (addBasicAuth)
            addHeaders(get);
        HttpResponse response = client.execute(get);
        return responseAsString(response);
    } catch (ClientProtocolException e) {
        internalServerError(e);
    } catch (IOException e) {
        internalServerError(e);
    } finally {
        client.getConnectionManager().shutdown();
    }
    return "";
 }

  protected DefaultHttpClient getHttpClient() {
    DefaultHttpClient client = new DefaultHttpClient();
    HttpParams params = client.getParams();
    if (this.connectionTimeOut != null) {
        HttpConnectionParams.setConnectionTimeout(params, this.connectionTimeOut);
        HttpConnectionParams.setSoTimeout(params, 3 * this.connectionTimeOut);
    }
    return client;
}

}