Java自定义类加载器实现类隔离详解

public interface Operator {
    /**
     * 测试连接
     * @param connectionInfo
     * @return
     */
    boolean testConnection(String connectionInfo);

    /**
     * 获取组件版本
     * @return
     */
    String getVersion(String connectionInfo);
}

public interface KafkaOperator extends Operator{
    /**
     * 获取topic列表
     * @param connectionInfo
     * @return
     */
    List<String> getTopics(String connectionInfo);

    /**
     * 创建topic
     * @param connectionInfo
     * @param topic
     * @return
     */
    boolean createTopic(String connectionInfo, String topic);

    /**
     * 删除topic
     * @param connectionInfo
     * @param topic
     * @return
     */
    boolean deleteTopic(String connectionInfo, String topic);
}

public class Entry implements KafkaOperator {
    @Override
    public List<String> getTopics(String connectionInfo) {
        return null;
    }

    @Override
    public boolean createTopic(String connectionInfo, String topic) {
        return false;
    }

    @Override
    public boolean deleteTopic(String connectionInfo, String topic) {
        return false;
    }

    @Override
    public boolean testConnection(String connectionInfo) {
        return false;
    }

    @Override
    public String getVersion(String connectionInfo) {
        return null;
    }
}

public static class MyClassLoader extends URLClassLoader {

        public MyClassLoader(URL[] urls) {
            super(urls);
        }

        public Class<?> loadClass(String name) throws ClassNotFoundException {
            synchronized (getClassLoadingLock(name)) {
                // 先检查当前类加载器是否已经装载该类
                Class<?> c = findLoadedClass(name);
                if (c == null) {
                    try {
                        // 在当前类加载器的路径下查找
                        c = findClass(name);
                    } catch (ClassNotFoundException e) {
                        // 说明在当前类加载器的路径下没有找到
                    }

                    if (c == null) {
                        // 走双亲委派机制
                        if (getParent() != null) {
                            c = getParent().loadClass(name);
                        }
                    }
                }
                return c;
            }
        }
    }

URL[] urls = null;
File dir = new File("/data/kafka/0.10");
if (dir.isDirectory()) {
    File[] files = dir.listFiles();
    urls = new URL[files.length];
    for (int i = 0; i < files.length; i++) {
        urls[i] = files[i].toURL();
    }
}

MyClassLoader contextClassLoader = new MyClassLoader(urls);

Class loadClass = contextClassLoader.loadClass("com.kamier.Entry");
Object entry = loadClass.newInstance();
Method method = loadClass.getDeclaredMethod("getTopics");
List<String> a = (List) method.invoke(entry, 参数);