API网关是微服务架构中的很重要的一个部分,内部有多个不同的服务提供给外部来使用,API网关可以对外做统一的入口,也可以在网关上做协议转换,权限控制和请求统计和限流等其他的工作
spring-cloud封装了Netflix提供的开源的API网关实现zuul,我们可以很方便地启动一个zuul网关的实例,并支持向eureka进行注册,并对在eureka上已经注册的服务进行代理
使用IDEA的spring initializer来创建一个zuul项目
填写相关的group类型等信息,选择使用gradle来进行构建
选择zuul和eureka client
选择项目位置和gradle安装的位置:
在启动类上添加 @EnableZuulProxy 注解,这个注解是@EnableZuulServer的加强版,不仅标识了这是一个zuul Server 而且启用了eureka注册中心和负载均衡ribbon
启动类的代码:
package com.jiaoyiping.springcloud.zuul;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.zuul.EnableZuulProxy;
@SpringBootApplication
@EnableZuulProxy
public class ZuulApplication {
public static void main(String[] args) {
SpringApplication.run(ZuulApplication.class, args);
}
}
zuul最本质的功能是做反向代理,路由转发和对请求的拦截和处理,路由转发的配置在配置文件中,zuul可以做一下几种形式的转发:
将请求重定向到一个外部的URL上,
如果我们要配置,符合/baidu前缀的请求都重定向到baidu.com去,可以做如下的配置:
zuul:
routes:
baidu:
path: /baidu/**
url: http://www.baidu.com
将请求转发到内部提供的请求路径上去,使用forforward:
比如,如果我们的网关自己提供了一个以/session开头的服务,我们想让对网关的请求中以/session开头的请求都让网关自己提供的这个服务来处理,则可以进行如下的配置
zuul:
routes:
session:
path: /session/**
url: forward:/session
对已经注册到eureka中的服务进行代理和请求转发,此时只需要提供eureka中服务的serviceid即可
zuul:
routes:
provider:
path: /provider/**
serviceId: PROVIDER
#(去请求目标服务的时候)是否丢掉前缀,根据需求来配置
stripPrefix: true
完整的配置如下:
spring:
application:
name: zuul
cloud:
inetutils:
preferred-networks: 192.168.1.
server:
port: 8084
tomcat:
uri-encoding: UTF-8
servlet:
context-path: /
logging:
config: classpath:logback.xml
zuul:
routes:
baidu:
path: /baidu/**
url: http://www.baidu.com
provider:
path: /provider/**
serviceId: PROVIDER
#(去请求目标服务的时候)是否丢掉前缀,根据需求来配置
stripPrefix: true
session:
path: /session/**
url: forward:/session
eureka:
instance:
hostname: 192.168.1.5
prefer-ip-address: true
instance-id: 192.168.1.5:${server.port}
client:
healthcheck:
enabled: true
registerWithEureka: true
fetchRegistry: true
service-url:
defaultZone: http://127.0.0.1:8081/eureka/
hystrix:
command:
default:
execution:
isolation:
thread:
timeoutInMilliseconds: 25000
ribbon:
MaxAutoRetries: 2
MaxAutoRetriesNextServer: 3
restclient:
enabled: true
zuul中的Filter的配置,zuul中提供了三种类型的Filter,preFilter,routeFilter和postFilter,分别对应请求中的不同的阶段,针对同一个请求,有一个RequestContext对象,在三个阶段的Filter中进行共享
假设我们要开发一个统计请求时间的功能,需要在preFilter里边记录开始时间,并将整个开始时间放在RequestContext中,在postFilter里边拿到开始时间,用当前的时间减去开始时间,就是请求执行的时间
定义一个preFilter:
package com.jiaoyiping.springcloud.zuul.filter;
import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import com.netflix.zuul.exception.ZuulException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cloud.netflix.zuul.filters.support.FilterConstants;
/**
* Created with Intellij IDEA
*
* @author: jiaoyiping
* Mail: jiaoyiping@gmail.com
* Date: 2018/04/05
* Time: 16:24
* To change this template use File | Settings | Editor | File and Code Templates
*/
public class TimeCostPreFilter extends ZuulFilter {
public static final String START_TIME_KEY = "start_time";
private Logger logger = LoggerFactory.getLogger(TimeCostPreFilter.class);
@Override
public String filterType() {
return FilterConstants.PRE_TYPE;
}
@Override
public int filterOrder() {
return 0;
}
/**
* 判断是否要拦截的逻辑
*
* @return
*/
@Override
public boolean shouldFilter() {
return true;
}
@Override
public Object run() throws ZuulException {
long startTime = System.currentTimeMillis();
RequestContext.getCurrentContext().set(START_TIME_KEY, startTime);
return null;
}
}
定义以postFilter:
package com.jiaoyiping.springcloud.zuul.filter;
import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import com.netflix.zuul.exception.ZuulException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cloud.netflix.zuul.filters.support.FilterConstants;
/**
* Created with Intellij IDEA
*
* @author: jiaoyiping
* Mail: jiaoyiping@gmail.com
* Date: 2018/04/05
* Time: 16:37
* To change this template use File | Settings | Editor | File and Code Templates
*/
public class TimeCostPostFilter extends ZuulFilter {
private static final String START_TIME_KE = "start_time";
private Logger logger = LoggerFactory.getLogger(TimeCostPostFilter.class);
@Override
public String filterType() {
return FilterConstants.POST_TYPE;
}
@Override
public int filterOrder() {
return 0;
}
@Override
public boolean shouldFilter() {
return true;
}
@Override
public Object run() throws ZuulException {
long startTime = (long) RequestContext.getCurrentContext().get(START_TIME_KE);
logger.info("请求完成,耗时{}秒", (System.currentTimeMillis() - startTime) / 1000);
return null;
}
}
在一个配置类中将这两个Filter注入:
package com.jiaoyiping.springcloud.zuul.config;
import com.jiaoyiping.springcloud.zuul.filter.PDSFilter;
import com.jiaoyiping.springcloud.zuul.filter.TimeCostPostFilter;
import com.jiaoyiping.springcloud.zuul.filter.TimeCostPreFilter;
import com.netflix.zuul.ZuulFilter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* Created with Intellij IDEA
*
* @author: jiaoyiping
* Mail: jiaoyiping@gmail.com
* Date: 2018/04/05
* Time: 17:32
* To change this template use File | Settings | Editor | File and Code Templates
*/
@Configuration
public class FilterConfig {
@Bean
public ZuulFilter timeCostPreFilter() {
return new TimeCostPreFilter();
}
@Bean
public ZuulFilter timeCostPostFilter() {
return new TimeCostPostFilter();
}
@Bean
public ZuulFilter pdsFilter() {
return new PDSFilter();
}
}
启动项目,可以发现,zuul网关已经注册到了eureka上:
请求provide对应的地址,发现,zuul可以成功地调用eureka上对应的服务,并将结果正确返回:
