Java遍歷包中所有類

package com.itkt.mtravel.hotel.util;

import java.io.File;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

public class PackageUtil {

    public static void main(String[] args) throws Exception {
        String packageName = "com.wang.vo.request.hotel";
        // List<String> classNames = getClassName(packageName);
        List<String> classNames = getClassName(packageName, false);
        if (classNames != null) {
            for (String className : classNames) {
                System.out.println(className);
            }
        }
    }

    /**
     * 獲取某包下（包括該包的所有子包）所有類
     * @param packageName 包名
     * @return 類的完整名稱
     */
    public static List<String> getClassName(String packageName) {
        return getClassName(packageName, true);
    }

    /**
     * 獲取某包下所有類
     * @param packageName 包名
     * @param childPackage 是否遍歷子包
     * @return 類的完整名稱
     */
    public static List<String> getClassName(String packageName, boolean childPackage) {
        List<String> fileNames = null;
        ClassLoader loader = Thread.currentThread().getContextClassLoader();
        String packagePath = packageName.replace(".", "/");
        URL url = loader.getResource(packagePath);
        if (url != null) {
            String type = url.getProtocol();
            if (type.equals("file")) {
                fileNames = getClassNameByFile(url.getPath(), null, childPackage);
            } else if (type.equals("jar")) {
                fileNames = getClassNameByJar(url.getPath(), childPackage);
            }
        } else {
            fileNames = getClassNameByJars(((URLClassLoader) loader).getURLs(), packagePath, childPackage);
        }
        return fileNames;
    }

    /**
     * 從項目文件獲取某包下所有類
     * @param filePath 文件路徑
     * @param className 類名集合
     * @param childPackage 是否遍歷子包
     * @return 類的完整名稱
     */
    private static List<String> getClassNameByFile(String filePath, List<String> className, boolean childPackage) {
        List<String> myClassName = new ArrayList<String>();
        File file = new File(filePath);
        File[] childFiles = file.listFiles();
        for (File childFile : childFiles) {
            if (childFile.isDirectory()) {
                if (childPackage) {
                    myClassName.addAll(getClassNameByFile(childFile.getPath(), myClassName, childPackage));
                }
            } else {
                String childFilePath = childFile.getPath();
                if (childFilePath.endsWith(".class")) {
                    childFilePath = childFilePath.substring(childFilePath.indexOf("\\classes") + 9, childFilePath.lastIndexOf("."));
                    childFilePath = childFilePath.replace("\\", ".");
                    myClassName.add(childFilePath);
                }
            }
        }

        return myClassName;
    }

    /**
     * 從jar獲取某包下所有類
     * @param jarPath jar文件路徑
     * @param childPackage 是否遍歷子包
     * @return 類的完整名稱
     */
    private static List<String> getClassNameByJar(String jarPath, boolean childPackage) {
        List<String> myClassName = new ArrayList<String>();
        String[] jarInfo = jarPath.split("!");
        String jarFilePath = jarInfo[0].substring(jarInfo[0].indexOf("/"));
        String packagePath = jarInfo[1].substring(1);
        try {
            JarFile jarFile = new JarFile(jarFilePath);
            Enumeration<JarEntry> entrys = jarFile.entries();
            while (entrys.hasMoreElements()) {
                JarEntry jarEntry = entrys.nextElement();
                String entryName = jarEntry.getName();
                if (entryName.endsWith(".class")) {
                    if (childPackage) {
                        if (entryName.startsWith(packagePath)) {
                            entryName = entryName.replace("/", ".").substring(0, entryName.lastIndexOf("."));
                            myClassName.add(entryName);
                        }
                    } else {
                        int index = entryName.lastIndexOf("/");
                        String myPackagePath;
                        if (index != -1) {
                            myPackagePath = entryName.substring(0, index);
                        } else {
                            myPackagePath = entryName;
                        }
                        if (myPackagePath.equals(packagePath)) {
                            entryName = entryName.replace("/", ".").substring(0, entryName.lastIndexOf("."));
                            myClassName.add(entryName);
                        }
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return myClassName;
    }

    /**
     * 從所有jar中搜索該包，並獲取該包下所有類
     * @param urls URL集合
     * @param packagePath 包路徑
     * @param childPackage 是否遍歷子包
     * @return 類的完整名稱
     */
    private static List<String> getClassNameByJars(URL[] urls, String packagePath, boolean childPackage) {
        List<String> myClassName = new ArrayList<String>();
        if (urls != null) {
            for (int i = 0; i < urls.length; i++) {
                URL url = urls[i];
                String urlPath = url.getPath();
                // 不必搜索classes文件夾
                if (urlPath.endsWith("classes/")) {
                    continue;
                }
                String jarPath = urlPath + "!/" + packagePath;
                myClassName.addAll(getClassNameByJar(jarPath, childPackage));
            }
        }
        return myClassName;
    }
}
由於我們並不確定jar包生成時採用的哪種方式，如果採用默認生成jar包的方式，那我們通過Thread.currentThread().getContextClassLoader().getResource()是獲取不到的，因此我增加了從所有jar包中搜索提供的包域名，這樣功能就完善了很多。
那麼就此關於“如何遍歷包中所有類”就結束了，PackageUtil這個類的功能還有些少，不排除日後進一步完善的可能，如果大家關於這個util有什麼新的需求或者建議，隨時歡迎大家提出。發現bug的，也請及時通知我以便改進。