package com.lms.common.util;
import java.io.File;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URL;
import java.nio.file.*;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Predicate;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
/**
 * @Author: 李孟帅
 * @Date: 2021-12-30 15:04
 * @Description:
 */
public class ClassScanner {
    Map<String, Class<?>> classMap = new HashMap<>();
    Predicate<String> packagePredicate;
    Predicate<Class<?>> classPredicate;
    public ClassScanner() {
    }
    public ClassScanner(Predicate<String> packagePredicate) {
        this.packagePredicate = packagePredicate;
    }
    public ClassScanner(Predicate<String> packagePredicate, Predicate<Class<?>> classPredicate) {
        this.packagePredicate = packagePredicate;
        this.classPredicate = classPredicate;
    }
    public Map<String, Class<?>> scanAll() throws Exception {
        String javaClassPath = System.getProperty("java.class.path");
        String[] classPaths = javaClassPath.split(";");
        for (String classPath : classPaths) {
            // jar包
            if (classPath.endsWith(".jar")) {
                scanClassesByJar(classPath);
            } else { //路径
                scanClassesByPath(classPath);
            }
        }
        return classMap;
    }
    // 加载路径下的class文件
    private void scanClassesByPath(String classPath) {
        File file = new File(classPath);
        if (!file.exists()) {
            return;
        }
        try {
            if (file.isDirectory() || classPath.endsWith(".class")) {
                Files.walkFileTree(Paths.get(classPath), new SimpleFileVisitor<Path>() {
                    @Override
                    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                        try {
                            if (file.toString().endsWith(".class")) {
                                String name = file.toString().replace(classPath + File.separator, "");
                                // 过滤包
                                name = name.replace(File.separatorChar + "", ".");
                                if (matchPackageName(name)) {
                                    String className = name.substring(0, name.length() - 6);
                                    Class<?> cls = Thread.currentThread().getContextClassLoader().loadClass(className);
                                    // 过滤类
                                    if (matchClass(cls)) {
                                        classMap.put(className, cls);
                                    }
                                }
                            }
                        } catch (Throwable e) {
                            e.printStackTrace();
                        }
                        return super.visitFile(file, attrs);
                    }
                });
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    // 加载所有的jar包内的class文件
    private void scanClassesByJar(String classPath) throws IOException {
        String file = "file:/" + classPath.replace("\\", "/") + "!/";
        URL url = new URL("jar", "", file);
        JarURLConnection jarURLConnection = (JarURLConnection) url.openConnection();
        JarFile jarFile = jarURLConnection.getJarFile();
        Enumeration<JarEntry> entries = jarFile.entries();
        while (entries.hasMoreElements()) {
            JarEntry jarEntry = entries.nextElement();
            String name = jarEntry.getName();
            // 过滤包
            if (!matchPackageName(name.replace("/", "."))) {
                continue;
            }
            // class文件
            if (!jarEntry.isDirectory() && name.endsWith(".class")) {
                try {
                    String className = name.substring(0, name.length() - 6).replace("/", ".");
                    Class<?> cls = Thread.currentThread().getContextClassLoader().loadClass(className);
                    // 过滤类
                    if (matchClass(cls)) {
                        classMap.put(className, cls);
                    }
                } catch (Throwable e) {
                    e.printStackTrace();
                }
            }
        }
    }
    // 过滤包
    private boolean matchPackageName(String name) {
        return packagePredicate == null || packagePredicate.test(name.replace("/", "."));
    }
    // 过滤类
    private boolean matchClass(Class<?> cls) {
        return classPredicate == null || classPredicate.test(cls);
    }
    public static void main(String[] args) throws Exception {
         // ClassScanner classScanner = new ClassScanner(p -> p.startsWith("java.lang"));
        ClassScanner classScanner = new ClassScanner(p -> p.startsWith("com.lms"), cls -> {
            return Object.class.isAssignableFrom(cls);
        });
        Map<String, Class<?>> classMap = classScanner.scanAll();
        classMap.forEach((k, v) -> System.out.println(k + "  --  " + v));
    }
}

使用

  public static void main(String[] args) throws Exception {
      // ClassScanner classScanner = new ClassScanner(p -> p.startsWith("java.lang"));
       ClassScanner classScanner = new ClassScanner(p -> p.startsWith("")
                , cls -> BasicLookAndFeel.class.isAssignableFrom(cls) && !Modifier.isAbstract(cls.getModifiers()));
        Map<String, Class<?>> classMap = classScanner.scanAll();
        classMap.forEach((k, v) -> System.out.println(k + "  --  " + v));
    }