Java扫描classpath指定包路径下所有class

在写框架时 经常需要扫描classpath指定包路径下带有某个Annotation的类，自己整理了一下 封装成一个工具类了，供大家参考。

源代码

ClassPathResourceScanner.java 如下：

package com.bytebeats.jupiter.ioc;import com.bytebeats.jupiter.util.ClassHelper;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import java.io.File;import java.io.IOException;import java.net.JarURLConnection;import java.net.URL;import java.net.URLDecoder;import java.util.*;import java.util.jar.JarEntry;import java.util.jar.JarFile;import java.util.regex.Pattern;/** * ${DESCRIPTION} * * @author Ricky Fung * @create 2016-12-11 16:02 */public class ClassPathCandidateComponentScanner {    private final Logger logger = LoggerFactory.getLogger(getClass());    public static final String CLASS_SUFFIX = ".class";    private static final Pattern INNER_PATTERN = java.util.regex.Pattern.compile("\\$(\\d+).", java.util.regex.Pattern.CASE_INSENSITIVE);    public Set<Class<?>> findCandidateComponents(String packageName) throws IOException {        if (packageName.endsWith(".")) {            packageName = packageName.substring(0, packageName.length()-1);        }        Map<String, String> classMap = new HashMap<>(32);        String path = packageName.replace(".", "/");        Enumeration<URL> urls = findAllClassPathResources(path);        while (urls!=null && urls.hasMoreElements()) {            URL url = urls.nextElement();            String protocol = url.getProtocol();            if ("file".equals(protocol)) {                String file = URLDecoder.decode(url.getFile(), "UTF-8");                File dir = new File(file);                if(dir.isDirectory()){                    parseClassFile(dir, packageName, classMap);                }else {                    throw new IllegalArgumentException("file must be directory");                }            } else if ("jar".equals(protocol)) {                parseJarFile(url, classMap);            }        }        Set<Class<?>> set = new HashSet<>(classMap.size());        for(String key : classMap.keySet()){            String className = classMap.get(key);            try {                set.add(ClassHelper.forName(className));            } catch (ClassNotFoundException e) {                e.printStackTrace();            }        }        return set;    }    protected void parseClassFile(File dir, String packageName, Map<String, String> classMap){        if(dir.isDirectory()){            File[] files = dir.listFiles();            for (File file : files) {                parseClassFile(file, packageName, classMap);            }        } else if(dir.getName().endsWith(CLASS_SUFFIX)) {            String name = dir.getPath();            name = name.substring(name.indexOf("classes")+8).replace("\\", ".");            System.out.println("file:"+dir+"\t class:"+name);            addToClassMap(name, classMap);        }    }    protected void parseJarFile(URL url, Map<String, String> classMap) throws IOException {        JarFile jar = ((JarURLConnection) url.openConnection()).getJarFile();        Enumeration<JarEntry> entries = jar.entries();        while (entries.hasMoreElements()) {            JarEntry entry = entries.nextElement();            if (entry.isDirectory()) {                continue;            }            String name = entry.getName();            if(name.endsWith(CLASS_SUFFIX)){                addToClassMap(name.replace("/", "."), classMap);            }        }    }    private boolean addToClassMap(String name, Map<String, String> classMap){        if(INNER_PATTERN.matcher(name).find()){ //过滤掉匿名内部类            System.out.println("anonymous inner class:"+name);            return false;        }        System.out.println("class:"+name);        if(name.indexOf("$")>0){ //内部类            System.out.println("inner class:"+name);        }        if(!classMap.containsKey(name)){            classMap.put(name, name.substring(0, name.length()-6)); //去掉.class        }        return true;    }    protected Enumeration<URL> findAllClassPathResources(String path) throws IOException {        if(path.startsWith("/")){            path = path.substring(1);        }        Enumeration<URL> urls = ClassHelper.getClassLoader().getResources(path);        return urls;    }}

使用方法

ClassPathCandidateComponentScanner scanner = new ClassPathCandidateComponentScanner();//要扫描的包名String packageName = "com.bytebeats";//获取该包下所有的类名称Set<Class<?>> set = scanner.findCandidateComponents(packageName);System.out.println(set.size());for (Class<?> cls : set){    System.out.println(cls.getName());}

这方面已经有一些不错的开源项目，例如：
reflections：https://github.com/ronmamo/reflections
Scannotation：http://scannotation.sourceforge.net/