[网络协议]Dubbo框架基本使用，cglib配置事务

什么是分布式系统：

分布式系统是若干独立计算机的集合，这些计算机对于用户来说就像单个相关的系统。

可以将用户，用户业务，订单业务分别放在不同服务器上。然后通过RPC远程过程调用

RPC：通过sockets传递信息，序列化反序列化传值

Dubbo特性：面向接口代理的高性能PRC调用，当a调用b，只需要调用b接口所在方法，Doubbo

就会自动去找b服务器的代码，帮助我们调用。

只能负载均衡：当用户业务有多个服务器在运行，根据每个服务器的请求多少，选择服务器

服务自动注册与发现：将所有的服务都注册到注册中心，当调用不同业务时，访问注册中心，找到服务器

高度扩展能力，运行期流量调度(比如更新可以先选部分服务器更新)，可视化服务治理与运维

运行流程：启动--提供者--注册中心 消费者--注册中心 若消费者下线，注册中心与消费者长连接方式

告诉消费者 监控中心：把消息发送到监控中心调用时间，调用信息等

使用Dubbo

建空项目，创建maven父项目，在创建module子项目doubbodemo_provider，添加依赖

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>dubbo</artifactId>
        <groupId>com.lzq</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>dubbodemo_provider</artifactId>
    <packaging>war</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <spring.version>5.0.5.RELEASE</spring.version>
    </properties>

    <dependencies>
        <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>2.6.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.7</version>
        </dependency>
        <dependency>
            <groupId>com.github.sgroschupf</groupId>
            <artifactId>zkclient</artifactId>
            <version>0.1</version>
        </dependency>
        <dependency>
            <groupId>javassist</groupId>
            <artifactId>javassist</artifactId>
            <version>3.12.1.GA</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.6</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>1.3.2</version>
        </dependency>

    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <configuration>
                    <!-- 指定端口 -->
                    <port>8083</port>
                    <!-- 请求路径 -->
                    <path>/</path>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

创建web目录在main下，webapp/WEB-INF/web.xml，添加

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        //监听器
        <param-value>classpath:applicationContext*.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
</web-app>

创建服务接口

public interface HelloService {
    public String sayHello(String name);
}
@Service
public class HelloServiceImpl implements HelloService {
    @Override
    public String sayHello(String name) {
        return "hello " + name;
    }
}
注意：服务实现类上使用的 Service 注解是Dubbo提供的，用于对外发布服务

创建对应文件applicationContext-service.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"
       xmlns:tx="http://www.springframework.org/schema/tx"
       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
         http://www.springframework.org/schema/tx
         http://www.springframework.org/schema/tx/spring-tx.xsd">


    <!--服务名称-->
    <dubbo:application name="dubbodemo_provider"/>

    <!--指定注册中心-->
    <dubbo:registry address="zookeeper://127.0.0.1:2181"/>

    <!--发布服务所设置协议和端口。调用者必须通过这个协议和端口来访问我这个服务接口。-->
    <dubbo:protocol name="dubbo" port="20883"/>

    <!--设置扫描包，主要扫描@Service注解-->
    <dubbo:annotation package="com.lzq"/>

 
</beans>

此时客户端查看zookeeper节点就能看到dubbo已经注册进去了

消费者

新建模块添加依赖

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>dubbo</artifactId>
        <groupId>com.lzq</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>dubbodemo_consumer</artifactId>

    <packaging>war</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <spring.version>5.0.5.RELEASE</spring.version>
    </properties>
    <dependencies>
        <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>2.6.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.7</version>
        </dependency>
        <dependency>
            <groupId>com.github.sgroschupf</groupId>
            <artifactId>zkclient</artifactId>
            <version>0.1</version>
        </dependency>
        <dependency>
            <groupId>javassist</groupId>
            <artifactId>javassist</artifactId>
            <version>3.12.1.GA</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <configuration>
                    <port>8082</port>
                    <path>/</path>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

创建webapp，在main下创建webapp/WEB-INF/web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
 <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:applicationContext-web.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

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"
       xmlns:tx="http://www.springframework.org/schema/tx"
       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
         http://www.springframework.org/schema/tx
         http://www.springframework.org/schema/tx/spring-tx.xsd">
</beans>

创建与生产者相同的接口

public interface Helloservice {
    String sayHello(String name);
}

编写Controller

@Controller
@RequestMapping("/demo")
public class HelloController {
    @Reference //dubbo提供的
    private HelloService helloService;

    @RequestMapping("/hello")
    @ResponseBody
    public String getName(String name){
        //远程调用
        String result = helloService.sayHello(name);
        System.out.println(result);
        return result;
    }
}

指定注册中心引入HelloService，在applicationContext-web.xml

  <!-- 当前应用名称，用于注册中心计算应用间依赖关系，注意：消费者和提供者应用名不要一样 -->
    <dubbo:application name="dubbodemo_consumer" />
    <!-- 连接服务注册中心zookeeper ip为zookeeper所在服务器的ip地址-->
    <dubbo:registry address="zookeeper://127.0.0.1:2181"/>
    <!-- 扫描的方式暴露接口  -->
    <dubbo:annotation package="com.lzq.controller" />
    <!-- 运行dubbo不检查提供者是否提前开启  -->
    <!-- <dubbo:consumer check="false"></dubbo:consumer> -->

此时启动生产者与消费者，就可调用到接口

提出共同接口

创建项目：dubbodemo_interface

把 项目dubbodemo_consumer 和 项目dubbodemo_provider当中的 接口 HelloService 拷贝到dubbodemo_interface工程里面

删除工程dubbodemo_consumer 和 工程dubbodemo_provider当中的 接口 HelloService

让生产者与消费者依赖新创建的接口模块

事务

生产者添加依赖

<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <version>5.1.47</version>
</dependency>
<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>druid</artifactId>
  <version>1.1.6</version>
</dependency>
<dependency>
  <groupId>org.mybatis</groupId>
  <artifactId>mybatis-spring</artifactId>
  <version>1.3.2</version>
</dependency>

xml配置文件

    <!--数据源-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" destroy-method="close">
        <property name="username" value="root" />
        <property name="password" value="root" />
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/test" />
    </bean>
    <!-- 事务管理器  -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <!--开启事务控制的注解支持
    proxy-target-class="true" 采用Cglib动态代理实现事务操作。
    -->
    <tx:annotation-driven transaction-manager="transactionManager" />

service添加注解? ?@Transactional

此时启动访问就会报错

原因：在HelloServiceImpl类上加入事务注解后，Spring会为此类基于JDK动态代理技术创建代理对象，创建的代理对象完整类名为com.sun.proxy.$Proxy35，而代理类没有service注解，导致Dubbo在进行包匹配时没有成功

此时使用cglib代理，dubbo的service是可以继承的，在xm中指定

  <!--开启事务控制的注解支持
    proxy-target-class="true" 采用Cglib动态代理实现事务操作。
    -->
    <tx:annotation-driven transaction-manager="transactionManager" proxy-target-class="true"/>

此时能发布，但是是按代理类来发布，需要在service中修改注解

@Service(interfaceClass = Helloservice.class)

负载均衡

负载均衡（Load Balance）：其实就是将请求分摊到多个操作单元上进行执行，从而共同完成工作任务。

在集群负载均衡时，Dubbo 提供了多种均衡策略（包括随机、轮询、最少活跃调用数、一致性Hash），缺省为random随机调用。

?随机算法 RandomLoadBalance（默认）

?轮询算法 RoundRobinLoadBalance

?最小活跃数算法 LeastActiveLoadBalance

?一致性hash算法 ConsistentHashLoadBalance

配置负载均衡策略，既可以在服务提供者一方配置，也可以在服务消费者一方配置，如下：

//在服务消费者一方配置负载均衡策略  随机
    @Reference(check = false,loadbalance = "random")
    private HelloService helloService;

服务器降级

@Reference(loadbalance = "random",timeout = 1000)