我可以使用正则表达式在Java类中查找方法吗？

Question

I know how to find a method in java using a fixed string,

someClass.getMethod("foobar", argTypes);

but is there a way to use a regular expression rather than a fixed string to find a method on a given class?

An example of the usage might be if I wanted to find a method that was called either "foobar" or "fooBar". Using a regular expression like "foo[Bb]ar" would match either of these method names.

Answer 1

You should apply your regexp on getDeclaredMethods () reflection method (or GetMethods() if you want only the public ones).

[Warning: both methods will throw a SecurityException if there is a security manager.]

You apply it on each name of each method returned by getDeclaredMethod() and only memorize in a Collection the compliant Methods.

Something like!

try
{
  final Pattern aMethodNamePattern = Pattern.compile("foo[Bb]ar");
  final List<Method> someMethods = aClass.getDeclaredMethods();
  final List<Method> someCompliantMethods = new ArrayList<Method>();
  for(final Method aMethod: someMethods)
  {
    final String aMethodName = aMethod.getName();
    final Matcher aMethodNameMatcher = aMethodNamePattern.getMatcher(aMethodName);
    if(aMethodNameMatcher.matches() == true)
    {
       someCompliantMethods.add(aMethod);
    }
}
catch(...) // catch all exceptions like SecurityException, IllegalAccessException, ...

Answer 2

Not directly. You could loop over all the methods and check each.

Pattern p = Pattern.compile("foo[Bb]ar");
for(Method m : someClass.getMethods()) {
  if(p.matcher(m.getName()).matches()) {
    return m; 
  }
}

Answer 3

You could do it by iterating over ALL the methods on a class and matching them that way.

Not that simple, but it would do the trick

    ArrayList<Method> matches = new ArrayList<Method>();
    for(Method meth : String.class.getMethods()) {
        if (meth.getName().matches("lengt.")){
            matches.add(meth);
        }
    }

Answer 4

No, you can't do that, but you can get a list of the method a class has and apply the regexp to them.

Method[] getMethods( String regexp, Class clazz, Object ... argTypes ){
    List<Method> toReturn = new ArrayList<Method>();
    for( Method m : clazz.getDeclaredMethods() ){ 
         if( m.getName().matches( regExp ) ) { // validate argTypes aswell here...
             toReturn.add( m );
         }
    }
    return toReturn.toArray(); 
}

Well something like that....

Answer 5

When I want look for some method using simple name pattern I use this org.reflections

For example looking for some methods which are public and name start with get:

Set<Method> getters = ReflectionUtils.getAllMethods(SomeClass.class, ReflectionUtils.withModifier(Modifier.PUBLIC), ReflectionUtils.withPrefix("get"));