Java反射：查找方法使用自定义AbstractProcessor [英] Java Reflection: Find method usage in custom AbstractProcessor

问题描述

我在反思新手。有什么方法来检测在调用特定的方法在哪里？例如：

I'm newbie in reflection. Is there any way to detect where is an specific method invoked? For example:

public class MyClass {

   public static void method(){//DO SOMETHING}

}

public class Test {

    public test(){
       MyClass.method();
    }

}

public class MyProcessor extends AbstractProcessor {

   public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {

      Method method = MyClass.class.getDeclaredMethod("method");

      Class classWhereMethodIsInvoked = obtainClassWhereMethodIsInvoked(method); 

   }

   public Class obtainClassWhereMethodIsInvoked(Method method) {
      //here I want to search one class that invoke that method, in this case Test.class
   }

}

是这样的可能还是我要疯了？

is something like this possible or I am going crazy?

推荐答案

是的，它是可行的，如果你真的想要它。您可以使用的ClassLoader通过类路径进行搜索，并通过所有的类文件扫描的方法名。下面是一个非常简单的例子来说明，这是可行的。在下面我找到的println方法的使用例子在这个类中使用。基本上你可以扩大范围，从在我的例子一个文件中所有的类文件。

Yes it doable if you really want it. You can use the classLoader to search through the class path and scan for the method name through all the class files. Below is a very simplistic example to show that it is doable. In the example below I find usage of the "println" method being used in this class. Essentially you can just broaden the scope from one file in my example to all the class files.

public class SearchClasses {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws FileNotFoundException {


//      InputStream is = SearchClasses.class.getClassLoader().getResourceAsStream("resources.SearchClasses.class");
        InputStream is = new FileInputStream(new File("build/classes/resources/SearchClasses.class"));

        boolean found = false;
        Scanner scanner = new Scanner(is);
        while (scanner.hasNext()) {
            if (scanner.nextLine().contains("println")) {
                System.out.print("println found");
                found = true;
                break;
            }
        }

        if (!found) {
                System.out.print("println NOT found");          
        }

    }

    public static void testMethod() {
        System.out.println("testing");
    }

}

在我的IDE，我不得不用的FileInputStream访问类文件我正在寻找在....但如果​​你是通过jar文件搜索，那么你可以使用类加载器来代替。您需要机制，通过所有的类路径进行搜索...这不是不可能的，但我离开我们的简洁。

In my IDE I had to use the FileInputStream to access the class file I was searching in.... but if you are searching through jar files then you can use the classLoader instead. You would need mechanism to search through all of the class path... this is not impossible but I left it our for brevity.

编辑：这里是企图得到它你的方法完全工作..搜索在类路径中的所有文件

Here is an attempt to get it working completely.. searches all files in class path for your method.

public class SearchClasses {

    /**
     * @param args the command line arguments
     * @throws java.io.FileNotFoundException
     */
    public static void main(String[] args) throws FileNotFoundException, IOException {

        printAllFileWithMethod("println");
    }

    public static void printAllFileWithMethod(String methodName) throws FileNotFoundException, IOException {
        Enumeration<URL> roots = SearchClasses.class.getClassLoader().getResources("");

        List<File> allClassFiles = new ArrayList<>();
        while (roots.hasMoreElements()) {
            File root = new File(roots.nextElement().getPath());
            allClassFiles.addAll(getFilesInDirectoryWithSuffix(root, "class"));
        }

        for (File classFile : allClassFiles) {
            InputStream is = new FileInputStream(classFile);

            boolean found = false;
            Scanner scanner = new Scanner(is);
            while (scanner.hasNext()) {
                if (scanner.nextLine().contains(methodName)) {
                    System.out.print(methodName + " found in " + classFile.getName() + "\n");
                    found = true;
                    break;
                }
            }

        }
    }

    public static void testMethod() {
        System.out.println("testing");
    }

    static List<File> getFilesInDirectoryWithSuffix(File dir, String suffix) {
        List<File> foundFiles = new ArrayList<>();
        if (!dir.isDirectory()) {
            return foundFiles;
        }
        for (File file : dir.listFiles()) {
            if (file.isDirectory()) {
                foundFiles.addAll(getFilesInDirectoryWithSuffix(file, suffix));
            } else {
                String name = file.getName();
                if (name.endsWith(suffix)) {
                    foundFiles.add(file);
                }
            }

        }
        return foundFiles;
    }

}

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