如何在PMD中为Java注释创建规则？

Question

Could someone please help me to create rule in pmd for eclipse? I am unable to start even i followed through PMD official site. I am planning to create rule in java instead of XPath rule. Any simple guidelines to start it? Thanks

Answer 1

Try the 'Write a rule using Java' method as you can easily start this way and later you can try with XPath expressions. You can follow these steps alongside the official link .

• Start with the src package that comes with PMD (eg pmd-4.2.x\\src), create your java class inside an existing package (eg pmd-4.2.5\\src\\net\\sourceforge\\pmd\\rules\\basic). In this case it is the following sample code (WhileLoopsMustUseBracesRule) :

    package net.sourceforge.pmd.rules.basic;

    import net.sourceforge.pmd.*;
    import net.sourceforge.pmd.ast.*;

    public class WhileLoopsMustUseBracesRule extends AbstractRule {
        public Object visit(ASTWhileStatement node, Object data) {
            SimpleNode firstStmt = (SimpleNode)node.jjtGetChild(1);
            if (!hasBlockAsFirstChild(firstStmt)) {
                addViolation(data, node);
            }
            return super.visit(node,data);
        }
        private boolean hasBlockAsFirstChild(SimpleNode node) {
            return (node.jjtGetNumChildren() != 0 && (node.jjtGetChild(0) instanceof ASTBlock));
        }
    }

• Append the following rule inside basic.xml(pmd-4.2.5\\rulesets\\basic.xml) :

  Copy paste the xml content from "Put the WhileLoopsMustUseBracesRule rule in a ruleset file" section to basic.xml.

  Replace the line

   class="WhileLoopsMustUseBracesRule"> 

  with

   class="net.sourceforge.pmd.rules.basic.WhileLoopsMustUseBracesRule"> 

  as you must have created the java file (WhileLoopsMustUseBracesRule.java) inside package "net.sourceforge.pmd.rules.basic"

• Run this command from cmd prompt if in windows.

    pmd.bat C:\JAVAFILE_ON_WHICH_YOU_WANT_TO_RUN_THIS_RULE xml C:\PMD\pmd-4.2.5\pmd-4.2.5\rulesets\basic.xml 

• For the nix os (linux/MacOS), use pmd.sh instead of pmd.bat
• Once you are able to get it running, you can create your own rule inside your own package.

Hope this helps.!

Answer 2

I wrote a tutorial a while back with some sample code that could be helpful.

http://www.techtraits.ca/writting-pretty-code-with-pmd/