If the user specifies an unusable Java, let them know that the binary…

… will be used

Provides a popup that explains what happened and has buttons to:
- Set "prefer binary" to true so they don't see the popup again
- Provide the download link for Java so they can update Java if necessary

This popup doesn't appear if the user doesn't have Java installed, and this popup doesn't block the language server startup (i.e. we go ahead and launch the binary server before the user clicks anything on the popup).

src/extension.ts

@@ -11,7 +11,7 @@
  */
 
 import * as fs from 'fs-extra';
-import { ExtensionContext, Uri, commands, extensions, languages } from "vscode";
+import { ConfigurationTarget, ExtensionContext, Uri, commands, extensions, languages, window, workspace } from "vscode";
 import { Executable, LanguageClient } from 'vscode-languageclient/node';
 import { XMLExtensionApi } from './api/xmlExtensionApi';
 import { getXmlExtensionApiImplementation } from './api/xmlExtensionApiImplementation';
@@ -46,6 +46,17 @@ export async function activate(context: ExtensionContext): Promise<XMLExtensionA
   try {
     requirementsData = await requirements.resolveRequirements(context);
   } catch (error) {
+    if (!workspace.getConfiguration('xml').get('server.preferBinary') && error.message !== requirements.NO_JAVA_FOUND) {
+      const USE_BINARY = 'Always use binary server';
+      void window.showWarningMessage(error.message + ' The binary server will be used instead. Please consider downloading and installing a recent Java runtime, or configuring vscode-xml to always use the binary server.', USE_BINARY, error.label) //
+        .then(button => {
+          if (button === error.label) {
+            commands.executeCommand('vscode.open', error.openUrl);
+          } else if (button === USE_BINARY) {
+            workspace.getConfiguration('xml').update('server.preferBinary', true, ConfigurationTarget.Global);
+          }
+        });
+    }
     requirementsData = {} as requirements.RequirementsData;
   }
 

src/server/requirements.ts

@@ -11,6 +11,8 @@ import * as expandHomeDir from 'expand-home-dir';
 const isWindows = process.platform.indexOf('win') === 0;
 const JAVA_FILENAME = 'java' + (isWindows ? '.exe' : '');
 
+export const NO_JAVA_FOUND = "Java runtime could not be located.";
+
 export interface RequirementsData {
   java_home: string;
   java_version: number;
@@ -50,7 +52,7 @@ async function checkJavaRuntime(context: ExtensionContext): Promise<string> {
   if (javaHome) {
     javaHome = expandHomeDir(javaHome);
     if (!pathExists.sync(javaHome)) {
-      throw openJDKDownload(source + ' points to a missing folder');
+      throw openJDKDownload(source + ' points to a missing folder.');
     } else if (!pathExists.sync(path.resolve(javaHome, 'bin', JAVA_FILENAME))) {
       throw openJDKDownload(source + ' does not point to a Java runtime.');
     }
@@ -62,7 +64,7 @@ async function checkJavaRuntime(context: ExtensionContext): Promise<string> {
     sortJdksBySource(javaRuntimes);
     javaHome = javaRuntimes[0].homedir;
   } else {
-    throw openJDKDownload("Java runtime could not be located. Please download and install Java or use the binary server.");
+    throw openJDKDownload(NO_JAVA_FOUND);
   }
   return javaHome;
 }
@@ -153,7 +155,7 @@ function checkJavaVersion(java_home: string): Promise<number> {
     cp.execFile(java_home + '/bin/java', ['-version'], {}, (error, stdout, stderr) => {
       const javaVersion = parseMajorVersion(stderr);
       if (javaVersion < 11) {
-        reject(openJDKDownload('Java 11 or more recent is required to run. Please download and install a recent Java runtime.'));
+        reject(openJDKDownload('The Java version specified is older than Java 11.'));
       }
       else {
         resolve(javaVersion);