Show the Java version in the Program Info dialog.

vasl_templates/webapp/main.py

@@ -14,7 +14,7 @@ from flask import request, render_template, jsonify, send_file, redirect, url_fo
 
 from vasl_templates.webapp import app, shutdown_event
 from vasl_templates.webapp.vassal import VassalShim
-from vasl_templates.webapp.utils import MsgStore, parse_int
+from vasl_templates.webapp.utils import MsgStore, get_java_version, parse_int
 import vasl_templates.webapp.config.constants
 from vasl_templates.webapp.config.constants import BASE_DIR, DATA_DIR, IS_FROZEN
 from vasl_templates.webapp import globvars
@@ -182,6 +182,7 @@ def get_program_info():
     for key in [ "VASSAL_DIR", "VASL_MOD", "VASL_EXTNS_DIR", "BOARDS_DIR",
                  "JAVA_PATH", "WEBDRIVER_PATH", "CHAPTER_H_NOTES_DIR", "USER_FILES_DIR" ]:
         params[ key ] = app.config.get( key )
+    params[ "JAVA_VERSION" ] = get_java_version()
 
     def parse_timestamp( val ):
         """Parse a timestamp."""

vasl_templates/webapp/templates/program-info-content.html

@@ -33,7 +33,12 @@
 
 <table>
     <tr> <td class="key"> Java:
-         <td class="val path"> {%if JAVA_PATH%} {{JAVA_PATH}} {%else%} - {%endif%}
+         <td class="val path"> {%if JAVA_PATH%}
+            {{JAVA_PATH}}
+            {%if JAVA_VERSION%} <span class="info"> ({{JAVA_VERSION}}) </span> {%endif%}
+        {%else%}
+            -
+        {%endif%}
     <tr> <td class="key"> Web driver:
          <td class="val path"> {%if WEBDRIVER_PATH%} {{WEBDRIVER_PATH}} {%else%} - {%endif%}
 </table>

vasl_templates/webapp/utils.py

@@ -2,6 +2,7 @@
 
 import os
 import shutil
+import subprocess
 import io
 import tempfile
 import pathlib
@@ -212,6 +213,48 @@ def remove_alpha_from_image( img ):
 
 # ---------------------------------------------------------------------
 
+def get_java_version():
+    """Get the version of the configured Java runtime."""
+    java_path = get_java_path()
+    if not java_path:
+        return None
+    try:
+        args = [ java_path, "-version" ]
+        kwargs = {
+            "capture_output": True, "text": True,
+            "stdin": subprocess.DEVNULL,
+        }
+        if is_windows():
+            kwargs["creationflags"] = 0x8000000 # nb: win32process.CREATE_NO_WINDOW
+        proc = subprocess.run( args, check=True, **kwargs )
+        return proc.stderr.split( "\n" )[0]
+    except Exception as ex: #pylint: disable=broad-except
+        logging.error( "Can't get Java version: %s", ex )
+        return "???"
+
+def get_java_path():
+    """Locate the Java runtime."""
+
+    # get the configured path to Java
+    java_path = app.config.get( "JAVA_PATH" )
+
+    # check if we should use the Java that now comes bundled with VASSAL
+    if not java_path and is_windows():
+        vassal_dir = app.config.get( "VASSAL_DIR" )
+        if vassal_dir:
+            fname = os.path.join( vassal_dir, "jre/bin/java.exe" )
+            if os.path.isfile( fname ):
+                java_path = fname
+
+    # check if we've found a Java runtime
+    if not java_path:
+        # nope - hope that there's one on the PATH
+        java_path = "java"
+
+    return java_path
+
+# ---------------------------------------------------------------------
+
 def change_extn( fname, extn ):
     """Change a filename's extension."""
     return pathlib.Path( fname ).with_suffix( extn )

vasl_templates/webapp/vassal.py

@@ -18,7 +18,7 @@ from flask import request, jsonify
 
 from vasl_templates.webapp import app, globvars
 from vasl_templates.webapp.config.constants import BASE_DIR, IS_FROZEN
-from vasl_templates.webapp.utils import TempFile, SimpleError, compare_version_strings, is_windows
+from vasl_templates.webapp.utils import TempFile, SimpleError, get_java_path, compare_version_strings
 from vasl_templates.webapp.webdriver import WebDriver
 from vasl_templates.webapp.vasl_mod import get_reverse_remapped_gpid
 
@@ -394,8 +394,8 @@ class VassalShim:
         # initialize
         logger = logging.getLogger( "vassal_shim" )
 
-        # figure out where Java is
-        java_path = app.config.get( "JAVA_PATH" )
+        # locate the Java runtime
+        java_path = get_java_path()
         java8_path = app.config.get( "JAVA8_PATH" )
         if java8_path:
             # FUDGE! From 3.3, VASSAL no longer works with Java 8. We want to mantain back-compatibility
@@ -412,13 +412,6 @@ class VassalShim:
             if compare_version_strings( mo.group(), "3.3.0" ) < 0:
                 # we're using a legacy version of VASSAL - use Java 8
                 java_path = java8_path
-        if not java_path and is_windows():
-            # we're on Windows - try to use the Java that is now bundled with VASSAL
-            fname = os.path.join( self._get_vassal_dir(), "jre/bin/java.exe" )
-            if os.path.isfile( fname ):
-                java_path = fname
-        if not java_path:
-            java_path = "java" # nb: this must be in the PATH
 
         # prepare the command
         class_path = app.config.get( "JAVA_CLASS_PATH" )