dubbo 遠端服務無法呼叫

web 工程，本地的 dubbo 引用可以初始化，可是無法初始化遠端的 dubbo 引用
這種情況基本上是因為沒有引用 zookeeper 導致的，新增一下 對應的 zookeeper 引用即可：

<!-- dubbo begin -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>dubbo</artifactId>
        <version>${dubbo.version}</version>
        <exclusions>
            <exclusion>
                <groupId>org.springframework</groupId>
                <artifactId>spring</artifactId>
            </exclusion>
            <exclusion>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
            </exclusion>
            <exclusion>
                <groupId>commons-logging</groupId>
                <artifactId>commons-logging</artifactId>
            </exclusion>
            <exclusion>
                <groupId>org.jboss.netty</groupId>
                <artifactId>netty</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <dependency>
        <groupId>org.apache.zookeeper</groupId>
        <artifactId>zookeeper</artifactId>
        <version>${zookeeper.version}</version>
    </dependency>

    <dependency>
        <groupId>io.netty</groupId>
        <artifactId>netty-transport-udt</artifactId>
        <version>${netty.version}</version>
    </dependency>
    <dependency>
        <groupId>io.netty</groupId>
        <artifactId>netty-all</artifactId>
        <version>${netty.version}</version>
    </dependency>

    <dependency>
        <groupId>com.github.sgroschupf</groupId>
        <artifactId>zkclient</artifactId>
        <version>${zkclient.version}</version>
    </dependency>
<!-- dubbo end -->