Spring扩展之基于HandlerMapping实现接口灰度发布实例
作者：轻尘×
这篇文章主要介绍了Spring扩展之基于HandlerMapping实现接口灰度发布实例,灰度发布是指在黑与白之间,能够平滑过渡的一种发布方式,灰度发布可以保证整体系统的稳定,在初始灰度的时候就可以发现、调整问题,以保证其影响度,需要的朋友可以参考下
背景
面试经常被问到，你了解spring源码吗？有基于spring做过什么扩展吗？
除了PropertyPlaceholderConfigurer处理占位符(被说烂了)还有其他的吗？
看了springmvc的源码，有了一个新的案例可讲(吹)
基于HandlerMapping实现接口灰度发布
说这个之前可以先铺垫一下，将故事讲的生动一点，我们来简单模拟一下。
面试官：“简历上说你对spring源码比较熟悉，能简单讲讲你对ioc、aop的理解吗？”
张三：“ioc是……aop是……巴拉巴拉”
(背了一大段八股文，毫无新意，面试官面无表情，然后打断张三，继续问)
面试官：你说对spring源码很熟悉，有多熟悉，在实际开发中有用过？扩展过吗？
张三：“有过呀，当时有个系统，升级改动比较大，对于同一批接口，老用户和新用户返回的数据不一样，为了实现系统的最小化改动，我当时就用spring的HandlerMapping解决了这个问题，前端访问的接口不变，只在参数中加一个接口版本号，就能实现灰度……，具体实现是这样的”
实现方案
自定义注解
新增一个自定义注解，用来标注接口的适配的版本号，默认为1.0版本
package com.fast.alibaba.annotation;
import java.lang.annotation.*;
/**
* 自定义版本号注解
*/
@Documented
@Target({ElementType.TYPE,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface ApiVersion {
double value() default 1.0;
}
自定义HandleMapping
自定义HandleMapping，继承spring家的HandleMapping，并重写两个getCustomTypeCondition方法
package com.fast.alibaba.handlemapping;
import com.fast.alibaba.annotation.ApiVersion;
import com.fast.alibaba.condition.ApiVersionRequestCondition;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.web.servlet.mvc.condition.RequestCondition;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
import java.lang.reflect.Method;
public class ApiVersionHandleMapping extends RequestMappingHandlerMapping {
@Override
protected RequestCondition<?> getCustomTypeCondition(Class<?> handlerType) {
ApiVersion apiVersion = AnnotationUtils.getAnnotation(handlerType, ApiVersion.class);
return new ApiVersionRequestCondition(apiVersion != null ? apiVersion.value() : 1.0);
}
@Override
protected RequestCondition<?> getCustomMethodCondition(Method method) {
ApiVersion apiVersion = AnnotationUtils.getAnnotation(method, ApiVersion.class);
if(apiVersion == null){
apiVersion = AnnotationUtils.getAnnotation(method.getDeclaringClass(), ApiVersion.class);
}
return new ApiVersionRequestCondition(apiVersion != null ? apiVersion.value() : 1.0);
}
}实现RequestCondition接口
以便识别前端传送的版本与接口上注解版本匹配
package com.fast.alibaba.condition;
import com.alibaba.cloud.commons.lang.StringUtils;
import org.springframework.web.servlet.mvc.condition.RequestCondition;
import javax.servlet.http.HttpServletRequest;
public class ApiVersionRequestCondition implements RequestCondition<ApiVersionRequestCondition> {
private double apiVersion = 1.0;
private static final String VERSION_NAME = "api-version";
public double getApiVersion() {
return apiVersion;
}
public ApiVersionRequestCondition(double apiVersion){
this.apiVersion=apiVersion;
}
@Override
public ApiVersionRequestCondition combine(ApiVersionRequestCondition method) {
return method;
}
@Override
public int compareTo(ApiVersionRequestCondition other, HttpServletRequest request) {
return Double.compare(other.getApiVersion(),this.getApiVersion());
}
@Override
public ApiVersionRequestCondition getMatchingCondition(HttpServletRequest request) {
double reqVersionDouble = 1.0;
String reqVersion = request.getHeader(VERSION_NAME);
if(StringUtils.isEmpty(reqVersion)){
reqVersion = request.getParameter(VERSION_NAME);
}
if(!StringUtils.isEmpty(reqVersion)){
reqVersionDouble = Double.parseDouble(reqVersion);
}
if(this.getApiVersion() == reqVersionDouble){
return this;
}
return null;
}
}自定义WebMvcRegistrations
package com.fast.alibaba.register;
import com.fast.alibaba.handlemapping.ApiVersionHandleMapping;
import org.springframework.boot.autoconfigure.web.servlet.WebMvcRegistrations;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
/**
* 注册自定义的 ApiVersionHandleMapping
*/
public class ApiVersionMappingRegister implements WebMvcRegistrations {
@Override
public RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
return new ApiVersionHandleMapping();
}
}注入WebMvcRegistrations
package com.fast.alibaba.config;
import com.fast.alibaba.register.ApiVersionMappingRegister;
import org.springframework.boot.autoconfigure.web.servlet.WebMvcRegistrations;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class BaseConfiguration {
@Bean
public WebMvcRegistrations getWebMvcRegistrations(){
return new ApiVersionMappingRegister();
}
}测试类
package com.fast.alibaba.controller;
import com.fast.alibaba.annotation.ApiVersion;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class TestHandlerMappingController {
@GetMapping("/getInfo")
@ApiVersion(1.0)
public String getSomeInfoByV1(){
return "version 1.0";
}
@GetMapping("/getInfo")
@ApiVersion(2.0)
public String getSomeInfoByV2(){
return "version 2.0";
}
@GetMapping("/getInfo")
@ApiVersion(3.0)
public String getSomeInfoByV3(){
return "version 3.0";
}
}
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