Add connection check

CHANGELOG.md

@@ -27,6 +27,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 - We added support for jumping to target entry when typing letter/digit after sorting a column in maintable [#6146](https://github.com/JabRef/jabref/issues/6146)
 - We added a new fetcher to enable users to search all available E-Libraries simultaneously. [koppor#369](https://github.com/koppor/jabref/issues/369)
 - We added the field "entrytype" to the export sort criteria [#6531](https://github.com/JabRef/jabref/pull/6531)
+- We added connection check function in network preference setting [#6560](https://github.com/JabRef/jabref/issues/6560)
 
 ### Changed
 

src/main/java/org/jabref/gui/preferences/NetworkTab.fxml

@@ -53,5 +53,7 @@
                              GridPane.rowIndex="5"/>
         <Label fx:id="proxyAttentionLabel" styleClass="warning-message"
                text="%Attention: Password is stored in plain text!" GridPane.columnIndex="2" GridPane.rowIndex="5"/>
+        <Button fx:id="checkConnectionButton" text="%Check connection" onAction="#checkConnection"
+                prefWidth="200.0" GridPane.columnIndex="1" GridPane.rowIndex="6"/>
     </GridPane>
 </fx:root>

src/main/java/org/jabref/gui/preferences/NetworkTabView.java

@@ -40,6 +40,7 @@ public class NetworkTabView extends AbstractPreferenceTabView<NetworkTabViewMode
     @FXML private Label proxyPasswordLabel;
     @FXML private CustomPasswordField proxyPassword;
     @FXML private Label proxyAttentionLabel;
+    @FXML private Button checkConnectionButton;
 
     private String proxyPasswordText = "";
     private int proxyPasswordCaretPosition = 0;
@@ -120,4 +121,9 @@ private void proxyPasswordMask(MouseEvent event) {
             proxyPasswordCaretPosition = 0;
         }
     }
+
+    @FXML
+    void checkConnection() {
+        viewModel.checkConnection();
+    }
 }

src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java

@@ -1,5 +1,6 @@
 package org.jabref.gui.preferences;
 
+import java.net.MalformedURLException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
@@ -8,13 +9,19 @@
 import javafx.beans.property.SimpleBooleanProperty;
 import javafx.beans.property.SimpleStringProperty;
 import javafx.beans.property.StringProperty;
+import javafx.scene.control.ButtonType;
+import javafx.scene.control.DialogPane;
+import javafx.scene.control.Label;
+import javafx.scene.control.TextField;
+import javafx.scene.layout.GridPane;
 
 import org.jabref.Globals;
 import org.jabref.gui.DialogService;
 import org.jabref.gui.remote.JabRefMessageHandler;
 import org.jabref.logic.l10n.Localization;
 import org.jabref.logic.net.ProxyPreferences;
 import org.jabref.logic.net.ProxyRegisterer;
+import org.jabref.logic.net.URLDownload;
 import org.jabref.logic.remote.RemotePreferences;
 import org.jabref.logic.remote.RemoteUtil;
 import org.jabref.model.strings.StringUtil;
@@ -25,6 +32,7 @@
 import de.saxsys.mvvmfx.utils.validation.ValidationMessage;
 import de.saxsys.mvvmfx.utils.validation.ValidationStatus;
 import de.saxsys.mvvmfx.utils.validation.Validator;
+import kong.unirest.UnirestException;
 
 public class NetworkTabViewModel implements PreferenceTabViewModel {
     private final BooleanProperty remoteServerProperty = new SimpleBooleanProperty();
@@ -215,6 +223,56 @@ public boolean validateSettings() {
         return true;
     }
 
+    /**
+     * Check the connection by using the given url. Used for validating the http proxy.
+     * The checking result will be appear when request finished.
+     * The checking result could be either success or fail, if fail, the cause will be displayed.
+     */
+    public void checkConnection() {
+        DialogPane dialogPane = new DialogPane();
+        GridPane settingsPane = new GridPane();
+        settingsPane.setHgap(4.0);
+        settingsPane.setVgap(4.0);
+
+        Label messageLabel = new Label();
+        messageLabel.setText(Localization.lang("Warning: your settings will be saved.\nEnter any URL to check connection to:"));
+
+        TextField url = new TextField();
+        url.setText("http://");
+
+        settingsPane.add(messageLabel, 1, 0);
+
+        settingsPane.add(url, 1, 1);
+        dialogPane.setContent(settingsPane);
+        String title = Localization.lang("Check Proxy Setting");
+        dialogService.showCustomDialogAndWait(
+                title,
+                dialogPane,
+                ButtonType.OK, ButtonType.CANCEL)
+                .ifPresent(btn -> {
+                            if (btn == ButtonType.OK) {
+                                String connectionProblemText = Localization.lang("Problem with connection: ");
+                                String connectionSuccessText = Localization.lang("Connection Successful!");
+                                storeProxySettings();
+                                URLDownload dl;
+                                try {
+                                    dl = new URLDownload(url.getText());
+                                    int connectionStatus = dl.checkConnection();
+                                    if (connectionStatus == 200) {
+                                        dialogService.showInformationDialogAndWait(title, connectionSuccessText);
+                                    } else {
+                                        dialogService.showErrorDialogAndWait(title, connectionProblemText + Localization.lang("Request failed with status code ") + connectionStatus);
+                                    }
+                                } catch (MalformedURLException e) {
+                                    dialogService.showErrorDialogAndWait(title, connectionProblemText + e.getMessage());
+                                } catch (UnirestException e) {
+                                    dialogService.showErrorDialogAndWait(title, connectionProblemText + e.getMessage());
+                                }
+                            }
+                        }
+                );
+    }
+
     @Override
     public List<String> getRestartWarnings() {
         return restartWarning;

src/main/java/org/jabref/logic/net/URLDownload.java

@@ -42,6 +42,7 @@
 import org.jabref.model.util.FileHelper;
 
 import kong.unirest.Unirest;
+import kong.unirest.UnirestException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -171,6 +172,21 @@ public String getMimeType() {
         return "";
     }
 
+    /**
+     * Check the connection by using the HEAD request.
+     * UnirestException can be thrown for invalid request.
+     * @return the status code of the response
+     */
+    public int checkConnection() {
+        Unirest.config().setDefaultHeader("User-Agent", "Mozilla/5.0 (Windows; U; WindowsNT 5.1; en-US; rv1.8.1.6) Gecko/20070725 Firefox/2.0.0.6");
+        try {
+            int statusCode = Unirest.head(source.toString()).asString().getStatus();
+            return statusCode;
+        } catch (UnirestException e) {
+            throw e;
+        }
+    }
+
     public boolean isMimeType(String type) {
         String mime = getMimeType();
 

src/test/java/org/jabref/logic/net/URLDownloadTest.java

@@ -2,16 +2,20 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.net.MalformedURLException;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 
 import org.jabref.support.DisabledOnCIServer;
 
+import kong.unirest.UnirestException;
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
 
 public class URLDownloadTest {
 
@@ -91,4 +95,24 @@ public void downloadOfHttpsSucceeds() throws IOException {
         Path path = ftp.toTemporaryFile();
         assertNotNull(path);
     }
+
+    @Test
+    public void testCheckConnectionSuccess() throws MalformedURLException {
+        URLDownload google = new URLDownload(new URL("http://www.google.com"));
+
+        int statusCode = google.checkConnection();
+        assertEquals(200, statusCode);
+    }
+
+    @Test
+    public void testCheckConnectionFail() throws MalformedURLException {
+        URLDownload nonsense = new URLDownload(new URL("http://nonsenseadddress"));
+        try {
+            int statusCode = nonsense.checkConnection();
+            fail();
+        } catch (UnirestException e) {
+            return;
+        }
+    }
+
 }