2.7.0版本getContextPath方法：
```
protected String getContextPath(URL url) {
        String contextPath = url.getPath();
        return contextPath.endsWith("/") ? contextPath.substring(0,contextPath.length()-1) : contextPath;
    }
```
无法将方法置入web容器中，退回2.6.5版本的方法：
```
protected String getContextPath(URL url) {
        int pos = url.getPath().lastIndexOf("/");
        return pos > 0 ? url.getPath().substring(0, pos) : "";
    }
```
使用正常，两个方法应该不等价的。
@Test
    public void testNettyServer() {
        DemoService server = new DemoServiceImpl();
        ProviderModel providerModel = new ProviderModel(exportUrl.getServiceKey(), server, DemoService.class);
        ApplicationModel.initProviderModel(exportUrl.getServiceKey(), providerModel);
        URL nettyUrl = exportUrl.addParameter(Constants.SERVER_KEY, "netty");
        Exporter<DemoService> exporter = protocol.export(proxy.getInvoker(new DemoServiceImpl(), DemoService.class, nettyUrl));
        DemoService demoService = this.proxy.getProxy(protocol.refer(DemoService.class, nettyUrl));
        Integer echoString = demoService.hello(10, 10);
        assertThat(echoString, is(20));
        exporter.unexport();
    }
    @Test
    public void testServletWithoutWebConfig() {
        Assertions.assertThrows(RpcException.class, () -> {
            DemoService server = new DemoServiceImpl();
            ProviderModel providerModel = new ProviderModel(exportUrl.getServiceKey(), server, DemoService.class);
            ApplicationModel.initProviderModel(exportUrl.getServiceKey(), providerModel);
            URL servletUrl = exportUrl.addParameter(Constants.SERVER_KEY, "servlet");
            protocol.export(proxy.getInvoker(server, DemoService.class, servletUrl));
        });
    }
    @Test
    public void testErrorHandler() {
        Assertions.assertThrows(RpcException.class, () -> {
            DemoService server = new DemoServiceImpl();
            ProviderModel providerModel = new ProviderModel(exportUrl.getServiceKey(), server, DemoService.class);
            ApplicationModel.initProviderModel(exportUrl.getServiceKey(), providerModel);
            URL nettyUrl = exportUrl.addParameter(Constants.SERVER_KEY, "netty");
            Exporter<DemoService> exporter = protocol.export(proxy.getInvoker(server, DemoService.class, nettyUrl));