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。
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutorService;
import static java.util.concurrent.Executors.newSingleThreadExecutor;
import static org.apache.dubbo.common.Constants.ACCEPT_FOREIGN_IP;
import static org.apache.dubbo.common.Constants.ANY_VALUE;
import static org.apache.dubbo.common.Constants.BIND_IP_KEY;
import static org.apache.dubbo.common.Constants.BIND_PORT_KEY;
import static org.apache.dubbo.common.Constants.CATEGORY_KEY;
import static org.apache.dubbo.common.Constants.CHECK_KEY;
import static org.apache.dubbo.common.Constants.COMMA_SPLIT_PATTERN;
import static org.apache.dubbo.common.Constants.CONFIGURATORS_CATEGORY;
import static org.apache.dubbo.common.Constants.CONFIGURATORS_SUFFIX;
import static org.apache.dubbo.common.Constants.CONSUMERS_CATEGORY;
import static org.apache.dubbo.common.Constants.CONSUMER_PROTOCOL;
import static org.apache.dubbo.common.Constants.DEFAULT_DIRECTORY;
import static org.apache.dubbo.common.Constants.DEFAULT_REGISTER_CONSUMER_KEYS;
import static org.apache.dubbo.common.Constants.DEFAULT_REGISTER_PROVIDER_KEYS;
import static org.apache.dubbo.common.Constants.DEFAULT_REGISTRY;
import static org.apache.dubbo.common.Constants.EXPORT_KEY;
import static org.apache.dubbo.common.Constants.EXTRA_KEYS_KEY;
import static org.apache.dubbo.common.Constants.HIDE_KEY_PREFIX;
import static org.apache.dubbo.common.Constants.INTERFACES;
import static org.apache.dubbo.common.Constants.METHODS_KEY;
import static org.apache.dubbo.common.Constants.MONITOR_KEY;
import static org.apache.dubbo.common.Constants.OVERRIDE_PROTOCOL;
import static org.apache.dubbo.common.Constants.PROVIDERS_CATEGORY;
import static org.apache.dubbo.common.Constants.PROVIDER_PROTOCOL;
import static org.apache.dubbo.common.Constants.QOS_ENABLE;