fixes Issue #271

Readme.html

@@ -283,7 +283,7 @@ see javassist.Dump.
 
 <p>-version 3.26
 <ul>
-   <li>GitHub Issue #270 (PR #272), Issue #265 (PR #267).
+   <li>GitHub Issue #270 (PR #272), Issue #265 (PR #267), Issue #271 and #222.
 </ul>
 
 <p>-version 3.25 on April 16, 2019

src/main/javassist/ClassPool.java

@@ -113,6 +113,14 @@ public class ClassPool {
      */
     public static boolean releaseUnmodifiedClassFile = true;
 
+    /**
+     * If true, the contents of a jar file are cached after the jar
+     * file is opened.
+     *
+     * <p>The initial value is true.
+     */
+    public static boolean cacheOpenedJarFile = true;    // see ClassPoolTail.JarClassPath#openClassfile(String)
+
     protected ClassPoolTail source;
     protected ClassPool parent;
     protected Hashtable classes;        // should be synchronous

src/main/javassist/ClassPoolTail.java

@@ -159,9 +159,13 @@ final class JarClassPath implements ClassPath {
         URL jarURL = find(classname);
         if (null != jarURL)
             try {
-                java.net.URLConnection con = jarURL.openConnection();
-                con.setUseCaches(false);
-                return con.getInputStream();
+                if (ClassPool.cacheOpenedJarFile)
+                    return jarURL.openConnection().getInputStream();
+                else {
+                    java.net.URLConnection con = jarURL.openConnection();
+                    con.setUseCaches(false);
+                    return con.getInputStream();
+                }
             }
             catch (IOException e) {
                 throw new NotFoundException("broken jar file?: "