Zookeeper注册中心概述

Zookeeper介绍(配合Dubbox使用)

　　官方推荐使用zookeeoer注册中心,注册中心负责服务地址的注册和查找,相当于目录服务,提供提供者和消费者只在启动时与注册中心交互,注册中心不转发请求,压力小.

　　zookeeper是Apacahe Hadoop的子项目,是一个树形的目录服务,支持变更推送,适合作为Dubbox服务的注册中心,工业强度较高,可用于生产环境.

　　Zookeeper在Linux系统的安装

安装步骤:

第一步:安装Jdk

第二步:把zookeeper的压缩包上传到linux系统.

第三步:解压缩压缩包

tar -zxvf zookeeper-3.4.6.tar.gz

第四步:进入conf目录,吧zoo sample.cfg改名为zoo.cfg

Zookeeper服务启动

进入bin目录,启动服务输入命令

 ./zkServer.sh start

输出一下内容表示启动成功

关闭服务输入命令

./zkServer.sh stop

查看状态:

./zkServer.sh status

如果启动状态,提示:

如果未启动状态,提示:

如果想要配置离线约束:

这个地址:http://code.alibabatech.com/schema/dubbo/dubbo.xsd

不配置也是可以的.

入门的一个小Demo

配置Maven环境

-DarchetypeCatalog=internal

服务提供者开发:

开发步骤:

（1）创建Maven工程（WAR）dubboxdemo-service,  war项目  ，在pom.xml中引入依赖

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>cn.itcast.dubboxdemo</groupId>
  <artifactId>dubboxdemo-service</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
   <properties>
        <spring.version>4.2.4.RELEASE</spring.version>
   </properties>
    <dependencies>
        <!-- Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jms</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!-- dubbo相关 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
            <version>2.8.4</version>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>com.github.sgroschupf</groupId>
            <artifactId>zkclient</artifactId>
            <version>0.1</version>
        </dependency>
        <dependency>
            <groupId>javassist</groupId>
            <artifactId>javassist</artifactId>
            <version>3.11.0.GA</version>
        </dependency>
<dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>fastjson</artifactId>
      <version>1.2.28</version>
    </dependency>
    </dependencies>
   <build>
      <plugins>
          <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-compiler-plugin</artifactId>
              <version>2.3.2</version>
              <configuration>
                  <source>1.7</source>
                  <target>1.7</target>
              </configuration>
          </plugin>
          <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <configuration>
                    <!-- 指定端口 -->
                    <port>8081</port>
                    <!-- 请求路径 -->
                    <path>/</path>
                </configuration>
            </plugin>
      </plugins>
    </build>
</project>

（2）在工程的webapps下创建WEB-INF文件夹，创建web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">
    <!-- 加载spring容器 -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext*.xml</param-value>
    </context-param>
    <listener>        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
</web-app>

（3）创建业务接口

创建包cn.itcast.dubbodemo.service，用于存放业务接口，创建接口

package cn.itcast.dubbodemo.service;
/**
 * 业务接口
 * @author Administrator
 *
 */
public interface UserService {
    public String getName();
}

（4）创建业务实现类

创建包cn.itcast.dubbodemo.service.impl ，用于存放业务实现类。创建业务实现类：

package cn.itcast.dubbodemo.service.impl;
import com.alibaba.dubbo.config.annotation.Service;
import cn.itcast.dubbodemo.service.UserService;
@Service
public class UserServiceImpl implements UserService {
    public String getName() {
        return "itcast";
    }
}

注意：Service注解与原来不同，需要引入com.alibaba包下的

（5）编写配置文件

在src/main/resources下创建applicationContext-service.xml ,内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:dubbo="http://code.alibabatech.com/schema/dubbo" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <dubbo:application name="dubboxdemo-service"/>
<dubbo:registry address="zookeeper://192.168.200.128:2181"/>
<dubbo:annotation package="cn.itcast.dubboxdemo.service" />
</beans>

注意：dubbo:annotation用于扫描@Service注解。

3.5.2服务消费者开发

开发步骤：

（1）创建Maven工程（WAR）dubboxdemo-web, war项目，在pom.xml引入依赖，同“dubboxdemo-service”工程。区别就是把tomcat插件的运行端口改为8082 。

（2）在webapps目录下创建WEB-INF 目录，并创建web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">
   <!-- 解决post乱码 -->
    <filter>
        <filter-name>CharacterEncodingFilter</filter-name>        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>CharacterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
  <servlet>
      <servlet-name>springmvc</servlet-name>      <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
      <!-- 指定加载的配置文件 ，通过参数contextConfigLocation加载-->
      <init-param>
          <param-name>contextConfigLocation</param-name>
          <param-value>classpath:applicationContext-web.xml</param-value>
      </init-param>
  </servlet>
  <servlet-mapping>
      <servlet-name>springmvc</servlet-name>
      <url-pattern>*.do</url-pattern>
  </servlet-mapping>
</web-app>

（3）拷贝业务接口

将“dubboxdemo-service”工程的cn.itcast.dubboxdemo.service 包以及下面的接口拷贝至此工程。

（4）编写Controller

package cn.itcast.dubboxdemo.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import cn.itcast.dubbodemo.service.UserService;
@Controller
@RequestMapping("/user")
public class UserController {
    @Reference
    private UserService userService;
    @RequestMapping("/showName")
    @ResponseBody
    public String showName(){
        return userService.getName();
    }
}

（5）编写spring配置文件

在src/main/resources下创建applicationContext-web.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:dubbo="http://code.alibabatech.com/schema/dubbo" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <mvc:annotation-driven>
      <mvc:message-converters register-defaults="true">
        <bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
          <property name="supportedMediaTypes" value="application/json"/>
          <property name="features">
            <array>
              <value>WriteMapNullValue</value>
              <value>WriteDateUseDateFormat</value>
            </array>
          </property>
        </bean>
      </mvc:message-converters>
    </mvc:annotation-driven>
    <!-- 引用dubbo 服务 -->
    <dubbo:application name="dubboxdemo-web" />
    <dubbo:registry address="zookeeper://192.168.200.128:2181"/>
     <dubbo:annotation package="cn.itcast.dubboxdemo.controller" />
</beans>

测试:

启动服务消费方和服务提供方,两个tomcat,以内使用了插件,所以直接启动就好.

tomcat7:run

在浏览器输入http://localhost:8082/user/showName.do，查看浏览器输出结果

package cn.itcast.dubbodemo.service.impl;

import com.alibaba.dubbo.config.annotation.Service;

import cn.itcast.dubbodemo.service.UserService;

@Service

publicclass UserServiceImpl implements UserService {

public String getName() {

return"itcast";

}

}