[BCEL-129] ClassFormatException when instrumenting a Java 5 class

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Component/s: Main
• External issue URL: https://issues.apache.org/bugzilla/show_bug.cgi?id=46722
• Severity: normal
• Priority: P2
• External issue ID: 46722
• Assignee: Apache Commons Developers
• Reporter: psramkumar
• Created: 17/Feb/09 09:22
• Updated: 07/Dec/23 21:04
• Resolved: 07/Mar/15 19:43

Description

Hi ,

I am using BCEL to instrument Java classes of web applications in JDK1.6 ,1.5 .We encountered a ClassFormat exception for classes using Generics which prevented application from loading.From https://issues.apache.org/bugzilla/show_bug.cgi?id=33549 I saw a workaround to delete "LocalVariableTypeTable". I followed that suggestion and loop through the attributes and deleted attribute named "LocalVariableTypeTable". Still while loading the application I get a ClassFormatException.

Example code in which I delete attribute "LocalvariableTypeTable" jc is JavaClass Object

        Method[] ma = jc.getMethods();
        for(int i = 0, x = ma.length; i < x; i++) {
            try {
                MethodGen mg = new MethodGen(ma[i],cg.getClassName(),cg.getConstantPool());
                Attribute[] atts = mg.getCodeAttributes();
                
                for (int j = 0; j < atts.length; j++) {
                    if (atts[j].getNameIndex() == mg.getConstantPool().lookupUtf8("LocalVariableTypeTable")) {
                        mg.removeCodeAttribute(atts[j]);
                    }
                }
            } catch(Exception o1) {
                output.write("exception " + o1);   
            }
        }

Also I get other error

Caused by: java.lang.ClassFormatError: LVTT entry for 'patterns' in class file org/springframework/classname does not match any LVT entry

and the application fails to load