问题
I need to change the signature of a method used all over the codebase.
Specifically, the method void log(String) will take two additional arguments (Class c, String methodName), which need to be provided by the caller, depending on the method where it is called. I can't simply pass null or similar.
To give an idea of the scope, Eclipse found 7000 references to that method, so if I change it the whole project will go down. It will take weeks for me to fix it manually.
As far as I can tell Eclipse's refactoring plugin of Eclipse is not up to the task, but I really want to automate it.
So, how can I get the job done?
回答1:
Great, I can copy a previous answer of mine and I just need to edit a tiny little bit:
I think what you need to do is use a source code parser like javaparser to do this.
For every java source file, parse it to a CompilationUnit, create a Visitor, probably using ModifierVisitorAdapter as base class, and override (at least) visit(MethodCallExpr, arg). Then write the changed CompilationUnit to a new File and do a diff afterwards.
I would advise against changing the original source file, but creating a shadow file tree may me a good idea (e.g. old file: src/main/java/com/mycompany/MyClass.java, new file src/main/refactored/com/mycompany/MyClass.java, that way you can diff the entire directories).
回答2:
Eclipse is able to do that using Refactor -> Change Method signature and provide default values for the new parameters.
For the class parameter the defaultValue should be this.getClass() but you are right in your comment I don't know how to do for the method name parameter.
回答3:
IntelliJ IDEA shouldn't have any trouble with this.
I'm not a Java expert, but something like this could work. It's not a perfect solution (it may even be a very bad solution), but it could get you started:
Change the method signature with IntelliJ's refactoring tools, and specify default values for the 2 new parameters:
c: self.getClass()
methodName: Thread.currentThread().getStackTrace()[1].getMethodName()
or better yet, simply specify null as the default values.
回答4:
I think that there are several steps to dealing with this, as it is not just a technical issue but a 'situation':
- Decline to do it in short order due to the risk.
- Point out the issues caused by not using standard frameworks but reinventing the wheel (as Paul says).
- Insist on using Log4j or equivalent if making the change.
- Use Eclipse refactoring in sensible chunks to make the changes and deal with the varying defaults.
I have used Eclipse refactoring on quite large changes for fixing old smelly code - nowadays it is fairly robust.
回答5:
Maybe I'm being naive, but why can't you just overload the method name?
void thing(paramA) {
thing(paramA, THE_DEFAULT_B, THE_DEFAULT_C)
}
void thing(paramA, paramB, paramC) {
// new method
}
回答6:
Do you really need to change the calling code and the method signature? What I'm getting at is it looks like the added parameters are meant to give you the calling class and method to add to your log data. If the only requirement is just adding the calling class/method to the log data then Thread.currentThread().getStackTrace() should work. Once you have the StackTraceElement[] you can get the class name and method name for the caller.
回答7:
If the lines you need replaced fall into a small number of categories, then what you need is Perl:
find -name '*.java' | xargs perl -pi -e 's/log\(([^,)]*?)\)/log(\1, "foo", "bar")/g'
I'm guessing that it wouldn't be too hard to hack together a script which would put the classname (derived from the filename) in as the second argument. Getting the method name in as the third argument is left as an exercise to the reader.
回答8:
Try refactor using intellij. It has a feature called SSR (Structural Search and Replace). You can refer classes, method names, etc for a context. (seanizer's answer is more promising, I upvoted it)
回答9:
I agree with Seanizer's answer that you want a tool that can parse Java. That's necessary but not sufficient; what you really want is a tool that can carry out a reliable mass-change.
To do this, you want a tool that can parse Java, can pattern match against the parsed code, install the replacement call, and spit out the answer without destroying the rest of the source code.
Our DMS Software Reengineering Toolkit can do all of this for a variety of languages, including Java. It parses complete java systems of source, builds abstract syntax trees (for the entire set of code).
DMS can apply pattern-directed, source-to-source transformations to achieve the desired change.
To achieve the OP's effect, he would apply the following program transformation:
rule replace_legacy_log(s:STRING): expression -> expression
" log(\s) " -> " log( \s, \class\(\), \method\(\) ) "
What this rule says is, find a call to log which has a single string argument, and replace it with a call to log with two more arguments determined by auxiliary functions class and method.
These functions determine the containing method name and containing class name for the AST node root where the rule finds a match.
The rule is written in "source form", but actually matches against the AST and replaces found ASTs with the modified AST.
To get back the modified source, you ask DMS to simply prettyprint (to make a nice layout) or fidelity print (if you want the layout of the old code preserved). DMS preserves comments, number radixes, etc.\
If the exisitng application has more than one defintion of the "log" function, you'll need to add a qualifier:
... if IsDesiredLog().
where IsDesiredLog uses DMS's symbol table and inheritance information to determine if the specific log refers to the definition of interest.
回答10:
Il fact your problem is not to use a click'n'play engine that will allow you to replace all occurences of
log("some weird message");
by
log(this.getClass(), new Exception().getStackTrace()[1].getMethodName());
As it has few chances to work on various cases (like static methods, as an example).
I would tend to suggest you to take a look at spoon. This tool allows source code parsing and transformation, allowing you to achieve your operation in a -obviously code based- slow, but controlled operation.
However, you could alos consider transforming your actual method with one exploring stack trace to get information or, even better, internally use log4j and a log formatter that displays the correct information.
回答11:
I would search and replace log( with log(@class, @methodname,
Then write a little script in any language (even java) to find the class name and the method names and to replace the @class and @method tokens...
Good luck
回答12:
If the class and method name are required for "where did this log come from?" type data, then another option is to print out a stack trace in your log method. E.g.
public void log(String text)
{
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw, true);
new Throwable.printStackTrace(pw);
pw.flush();
sw.flush();
String stackTraceAsLog = sw.toString();
//do something with text and stackTraceAsLog
}
来源：https://stackoverflow.com/questions/3906204/java-source-refactoring-of-7000-references