[编织消息框架][JAVA核心技术]动态代理应用9-扫描class

之前介绍的annotationProcessor能在编译时生成自定义class,但有个缺点，只能每次添加/删除java文件才会执行，那天换了个人不清楚就坑大了

还记得之前介绍的编译时处理，懒处理，还有个预处理没介绍对吧

预处理：应用程序启动前做的处理，如setup

扫描class处理

1.从ClassLoader 和 System.getProperty("java.class.path") 读取所有classPath 

2.解释每个classPath ，用正则匹配jar/class 文件

3.正则提取class文件类名，转换成class给上层处理

public class PackageScanner {
    private static final Logger LOGGER = LoggerFactory.getLogger(PackageScanner.class);

    /**
     * @param packageNames
     *            过滤的包名，如果为NULL即扫描所有类
     */
    public static void scan(Consumer<Class<?>> atcion, final String... packageNames) {
        Set<String> classPath = new HashSet<>();
        Set<String> filterPackage = new HashSet<>();
        if (packageNames == null || packageNames.length == 0) {
            String classpathProp = System.getProperty("java.class.path");
            if (classpathProp != null) {
            String[] classpathEntries = classpathProp.split(File.pathSeparator);
            for (String cpe : classpathEntries) {
                cpe = trimr(cpe, '/');
                classPath.add(new File(cpe).getAbsolutePath());
            }
            }
            ClassLoader cl = ClassLoader.getSystemClassLoader();
            URL[] urls = ((URLClassLoader) cl).getURLs();
            for (URL url : urls) {
            String path = trimr(url.getPath(), '/');
            classPath.add(new File(path).getAbsolutePath());
            }
        } else {
            Collections.addAll(classPath, packageNames);
            Collections.addAll(filterPackage, packageNames);
        }
        
        /***
         * 扫描有三种策略
         * 1.jar文件
         * 2.class文件
         * 3.classPath目录
         * */
        
        for (String path : classPath) {
            try {
                if (path.endsWith(".jar")) {
                    parseJar(path, filterPackage, atcion);
                }else if (new File(path).isDirectory()) {
                    parseFile(path, null, filterPackage, atcion);
                } else {
                    final String packageDirectory = path.replace('.', '/');
                    final Enumeration<URL> urls = Thread.currentThread().getContextClassLoader().getResources(packageDirectory);
                    while (urls.hasMoreElements()) {
                        final URL url = urls.nextElement();
                        if ("file".equals(url.getProtocol())) {
                            parseFile(url.getPath(), url.getPath().replace(packageDirectory, ""), filterPackage,atcion);
                        } else if ("jar".equals(url.getProtocol())) {
                            parseJar(url.getPath(),filterPackage, atcion);
                        }
                    }
                }
            } catch (Exception exception) {
                throw new RuntimeException(exception);
            }
        }
    }
}

parseJar，parseFile 比较长，感兴趣读者可查源码分析

有的JAR里的类读会出错,原因是没有依赖完整的包

测试：

public class TestScanClass {

    @Test
    public void testAll() {
        PackageScanner.scan((clz) -> {
            // System.out.println(clz);
        });
    }

    @Test
    public void testFilter1() {
        PackageScanner.scan((clz) -> {
            System.out.println(clz);
        } , "com.eyu.onequeue");
    }

    @Test
    public void testFilter() {
        Set<Class<?>> values = new HashSet<>();
        PackageScanner.scan((clz) -> {
            QModel modelAnno = ReflectUtil.getAnno(clz, QModel.class);
            if (modelAnno == null) {
                return;
            }
            values.add(clz);
        } , "com.eyu.onequeue");
        for (Class<?> clz : values) {
            if (clz.isInterface()) {
                QRpcFactory.registerSendProxy(clz);
                System.out.println("registerSendProxy : " + clz);
            } else {
                try {
                    QRpcFactory.registerReceiveProxy(clz.newInstance());
                    System.out.println("registerReceiveProxy : " + clz);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}