Changeset 15232

Timestamp:

2008-04-29T10:30:57+12:00 (16 years ago)

Author:

ak19

Message:

Better comparison between minimum required Java Version and running Java Version. Does numberwise comparison.

Location:

other-projects/trunk/gs3-webservices-democlient

Files:

• CheckJavaVersion.class (modified) ( previous)
• CheckJavaVersion.java (modified) (3 diffs)

other-projects/trunk/gs3-webservices-democlient/CheckJavaVersion.java

@@ +1 @@
+import java.util.regex.Pattern;
+
 
 public class CheckJavaVersion {
@@ -16 +18 @@
         String programName = "this program"; 
         // the version of java that's in use
-        String installedJavaVersion = System.getProperty("java.version");
+        String runningJavaVersion = System.getProperty("java.version");
         
         if(args.length > 0) {
@@ -26 +28 @@
         
         System.out.println("\nChecking for a compatible Java version..."
-                + "\nLooking for minimum version " + minimumVersion + ".x");
+                + "\nLooking for minimum version: " + minimumVersion);
         
-        if(installedJavaVersion.compareTo(minimumVersion) < 0) {
-            System.out.println(
-                "The current Java version " 
-                + installedJavaVersion 
-                + " is insufficient to run " 
-                + programName
-            );
+        // Version numbers can be of the form "1.5.0_2" 
+        // We want to split version numbers into the individual numbers
+        // For example: splitting 1.5.0_2 will give us {1,5,0,2},
+        // while splitting 1.5.0_10 will give us {1,5,0,10}.
+        // The comparison then is straightforward.
+        
+        // We will split version strings into the individual numbers
+        // using regular expressions. However, the tokens . and _ are
+        // reserved in regular expressions and need to be escaped: 
+        // Period: \Q.\E;  underscore: \Q_\E.
+        // Once escaped, it should be indicated in the regular expression
+        // that the two characters are separate tokens by using |, so 
+        // that the regex becomes: ".|_" -> \Q.\E|\Q_\E.
+        String period = Pattern.quote(".");
+        String underscore = Pattern.quote("_");
+        
+        String[] minVersionNums = minimumVersion.split(period+"|"+underscore);
+        String[] runningVersionNums =runningJavaVersion.split(period+"|"+underscore);
+        
+        boolean acceptable = true;
+        // only keep looping while we haven't gone past the end of either array
+        for(int i=0; i < minVersionNums.length && i < runningVersionNums.length; i++)
+        {
+            int min = Integer.parseInt(minVersionNums[i]);
+            int run = Integer.parseInt(runningVersionNums[i]);
+            if(run < min) { 
+                // fail: running version number is lower than corresponding 
+                // minimum version number
+                acceptable = false;
+                break;
+            }
+        }
+        
+        if(acceptable) {
+            System.out.println("Found compatible Java version " +runningJavaVersion);
+            System.exit(0); // acceptable case
+        } else {
+            System.out.println("The current Java version " + 
+                runningJavaVersion + " is insufficient to run " + programName);
             System.exit(-1);
-        } else {
-            System.out.println("Found compatible Java version " 
-                    + installedJavaVersion);
-            System.exit(0);
-        }
+        } 
     }
-
 }