Rest service accessible in Browser not in Java code

Question

I have created a restful webservice hosted on server A. I'm trying to call this service using a Java class in a client's vpn environment. The service on hitting from the code shows me error as Connection Refused but is accessible on calling in browser.

The same service I try to access from public internet with the same code, it works fine.

I'm using URLConnection to call the service in Java code. Also tried to apply below code but didn't help.

connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11");

What can be the possible reasons for that? Any Suggestions?

Edit : Code Attached

private final String crlf = "\r\n";
    private String url;
    private String boundary;
    private final int bufferSize = 4096;

    public UploadFiles(String argUrl) {
        url = argUrl;
        System.out.println(url);
        logEntry(url);
        boundary = "---------------------------4664151417711";
    }

    public int post() throws MalformedURLException, IOException {
        String charset = "UTF-8";
        String param = "value";
        String boundary = Long.toHexString(System.currentTimeMillis()); // Just generate some unique random value.
        String CRLF = "\r\n"; // Line separator required by multipart/form-data.

        URLConnection connection = new URL(url).openConnection();
        connection.setDoOutput(true);
        connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11");
        connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);

        try (
                OutputStream output = connection.getOutputStream();
                PrintWriter writer = new PrintWriter(new OutputStreamWriter(output, charset), true);) {

            File fileDir = new File(HomeController.configBean.getFilePath());
            File[] listFiles = fileDir.listFiles();

            for (File file : listFiles) {
                // Send text file.
                writer.append("--" + boundary).append(CRLF);
                writer.append("Content-Disposition: form-data; name=\"textFile\"; filename=\"" + file.getName() + "\"").append(CRLF);
                writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF); // Text file itself must be saved in this charset!
                writer.append(CRLF).flush();
                Files.copy(file.toPath(), output);
                output.flush(); // Important before continuing with writer!
                writer.append(CRLF).flush(); // CRLF is important! It indicates end of boundary.
            }
            // End of multipart/form-data.
            writer.append("--" + boundary + "--").append(CRLF).flush();
        } catch (IOException ex) {
            Logger.getLogger(UploadFiles.class.getName()).log(Level.SEVERE, null, ex);
        }

// Request is lazily fired whenever you need to obtain information about response.
        int responseCode = ((HttpURLConnection) connection).getResponseCode();
        System.out.println(responseCode); // Should be 200

        return responseCode;
    } // post() method

Edit 2 : Error

java.net.ConnectException: Connection refused: connect
        at java.net.DualStackPlainSocketImpl.connect0(Native Method)
        at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
        at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
        at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
        at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
        at java.net.PlainSocketImpl.connect(Unknown Source)
        at java.net.SocksSocketImpl.connect(Unknown Source)
        at java.net.Socket.connect(Unknown Source)
        at java.net.Socket.connect(Unknown Source)
        at sun.net.NetworkClient.doConnect(Unknown Source)
        at sun.net.www.http.HttpClient.openServer(Unknown Source)
        at sun.net.www.http.HttpClient.openServer(Unknown Source)
        at sun.net.www.http.HttpClient.<init>(Unknown Source)
        at sun.net.www.http.HttpClient.New(Unknown Source)
        at sun.net.www.http.HttpClient.New(Unknown Source)
        at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(Unknown
Source)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(Unknown Sou
rce)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Sour
ce)
        at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)
        at sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(Unknown
Source)
        at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(Unknown S
ource)
        at testfileupload.UsingURLConnection.uploadFilesUsingURLConnecton(UsingU
RLConnection.java:42)
        at testfileupload.FormUploadTestController.lambda$0(FormUploadTestContro
ller.java:62)
        at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Comp
ositeEventHandler.java:86)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventH
andlerManager.java:238)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventH
andlerManager.java:191)
        at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(C
ompositeEventDispatcher.java:59)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:58)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
        at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
        at javafx.event.Event.fireEvent(Event.java:198)
        at javafx.scene.Node.fireEvent(Node.java:8413)
        at javafx.scene.control.Button.fire(Button.java:185)
        at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(Bu
ttonBehavior.java:182)
        at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorS
kinBase.java:96)
        at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorS
kinBase.java:89)
        at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.h
andleBubblingEvent(CompositeEventHandler.java:218)
        at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Comp
ositeEventHandler.java:80)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventH
andlerManager.java:238)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventH
andlerManager.java:191)
        at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(C
ompositeEventDispatcher.java:59)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:58)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
        at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
        at javafx.event.Event.fireEvent(Event.java:198)
        at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
        at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
        at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
        at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotificatio
n.run(GlassViewEventHandler.java:381)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotificatio
n.run(GlassViewEventHandler.java:295)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEve
nt$354(GlassViewEventHandler.java:417)
        at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(Quantum
Toolkit.java:389)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(Glas
sViewEventHandler.java:416)
        at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
        at com.sun.glass.ui.View.notifyMouse(View.java:937)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.ja
va:191)
        at java.lang.Thread.run(Unknown Source)

Edit 3 :

I'm getting this connection refused error at OutputStream output = connection.getOutputStream();

Edit 4 :

I even tried the following code to add proxy.

System.setProperty("http.proxyHost", url.getHost()); // My restful service url hostname
System.setProperty("http.proxyPort", url.getPort()); // My restful service url port

Am I doing anything wrong here? Please suggest.

Can you please share the exact exception and a sample of your code? — greenPadawan, Feb 15 '19 at 04:36
will you put your working code , Like the URL that you are accessing from the browser and how you are trying to connect using java.net.URL. — Amit Kumar Lal, Feb 15 '19 at 04:37
`connection.setRequestProperty("Accept", "*/*");` (try this first, the rest are "different (unknown) things") — xerx593, Feb 15 '19 at 05:05
@xerx593 Using accept didn't solve the issue. :( Same error again. Attached the error log. — Harshita Sethi, Feb 15 '19 at 09:34
Is there maybe a required proxy that is configured in your browser but not in your Java App? — Sebastian, Feb 15 '19 at 09:46
@Sebastian I'm facing challenge in calling it from a client's VM. Won't know about their proxy settings. Can we write some java code to get that and match it into the code. — Harshita Sethi, Feb 15 '19 at 09:51
On clients VM... Could be anything network related then. Proxy, Firewall, Blocked ports... I'd try to ask the client about their infrastructure. — Sebastian, Feb 15 '19 at 09:58
@HarshitaSethi is it doesn't still add the code to close the connection and try with sample API like google url to see if it works. — Amit Kumar Lal, Feb 15 '19 at 11:35
Check if there's proxy setup in browser and not setup in your application. — Santosh, Feb 15 '19 at 14:37

Amit Kumar Lal · Answer 1 · 2019-02-15T13:28:56.630

I tried this with Postman sample API its working fine for me printing 200

public void UploadFiles(String argUrl) {
    url = argUrl;
    System.out.println(url);
    boundary = "---------------------------4664151417711";
}

public static void main(String...strings) throws MalformedURLException, IOException {
    String charset = "UTF-8";
    String param = "value";
    String boundary = Long.toHexString(System.currentTimeMillis()); // Just generate some unique random value.
    String CRLF = "\r\n"; // Line separator required by multipart/form-data.

    HttpURLConnection connection = (HttpURLConnection) new URL("https://postman-echo.com/post").openConnection();
    connection.setDoOutput(true);
    connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11");
    connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);

    try { 
        OutputStream output = connection.getOutputStream();
        PrintWriter writer = new PrintWriter(new OutputStreamWriter(output, charset), true);

        File fileDir = new File("C:\\Test");
        File[] listFiles = fileDir.listFiles();

        for (File file : listFiles) {
            // Send text file.
            writer.append("--" + boundary).append(CRLF);
            writer.append("Content-Disposition: form-data; name=\"textFile\"; filename=\"" + file.getName() + "\"").append(CRLF);
            writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF); // Text file itself must be saved in this charset!
            writer.append(CRLF).flush();
            Files.copy(file.toPath(), output);
            output.flush(); // Important before continuing with writer!
            writer.append(CRLF).flush(); // CRLF is important! It indicates end of boundary.
        }
        writer.append("--" + boundary + "--").append(CRLF).flush();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

    int responseCode = ((HttpURLConnection) connection).getResponseCode();
    System.out.println(responseCode); // Should be 200
    if(connection!=null) {
        connection.disconnect();
    }

}

@Harshita Sethi :- You need to close the connection , let me know if it works for you. — Amit Kumar Lal, Feb 15 '19 at 11:34
He is using HttpURLConnection class where you are using URLConnection class. Please change to HttpUrlConnection importing java.net.HttpURLConnection — Vigneshwaran, Feb 18 '19 at 04:56
I guess you meant the opposite .. and the classes belong to the same package it's better to use httpurl connection when dealing with http request. — Amit Kumar Lal, Feb 18 '19 at 04:58
@Vigneshwaran please go through this https://stackoverflow.com/questions/3920419/difference-between-urlconnection-httpurlconnection-and-httpsurlconnection — Amit Kumar Lal, Feb 18 '19 at 05:04

Rest service accessible in Browser not in Java code

1 Answers1