eclipse代码中使用到Launcher获取类加载器，找不到启动器类。

解决：移除系统依赖的jar包，重新导入。

只需要在project build path中先移除JRE System Library，再添加库JRE System Library，重新编译后就一切正常了。

        ClassLoader appClassLoader = ClassLoader.getSystemClassLoader();
        ClassLoader extClassloader = appClassLoader.getParent();
        ClassLoader bootstrapLoader  = extClassloader.getParent();
        System.out.println("the bootstrapLoader : " + bootstrapLoader);
        System.out.println("the extClassloader : " + extClassloader);
        System.out.println("the appClassLoader : " + appClassLoader);  

        System.out.println();
        System.out.println("bootstrapLoader加载以下文件：");  

        URL[] urls = Launcher.getBootstrapClassPath().getURLs();
        for (int i = ; i < urls.length; i++) {
            System.out.println(urls[i]);
        }  

        System.out.println();
        System.out.println("extClassloader加载以下文件：");
        System.out.println(System.getProperty("java.ext.dirs"));  

        System.out.println();
        System.out.println("appClassLoader加载以下文件：");
        System.out.println(System.getProperty("java.class.path"));