Springboot实现webAPI版本控制

1.定义一个自定义版本注解

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface ApiVersion {
    /**
     * @return版本号
     */
    int value( ) default 1;
}

2.自定义URL匹配规则ApiVersionCondition

package com.yangjunbo.helloword.properties;

import org.springframework.web.servlet.mvc.condition.RequestCondition;

import javax.servlet.http.HttpServletRequest;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/*接下来定义URL匹配逻辑，创建ApiVersionCondition类并继承RequestCondition接口，
        其作用是进行版本号筛选，将提取请求URL中的版本号与注解上定义的版本号进行对比，以此来判断某个请求应落在哪个控制器上。*/
public class ApiVersionCondition implements RequestCondition<ApiVersionCondition> {
    private final static Pattern VERSION_PREFIX_PATTERN = Pattern.compile(".*v(\\d+).*");

    private int apiVersion;
    ApiVersionCondition(int apiVersion) {
        this.apiVersion = apiVersion;
    }
    private int getApiVersion() {
        return apiVersion;
    }

    @Override
    public ApiVersionCondition combine(ApiVersionCondition apiVersionCondition) {
        return new ApiVersionCondition(apiVersionCondition.getApiVersion());
    }
    @Override
    public ApiVersionCondition getMatchingCondition(HttpServletRequest httpServletRequest) {
        Matcher m = VERSION_PREFIX_PATTERN.matcher(httpServletRequest.getRequestURI());
        if (m.find()) {
            Integer version = Integer.valueOf(m.group(1));
            if (version >= this.apiVersion) {
                //apiVersion = version;
                return this;
            }
        }
        return null;
    }
    @Override
    public int compareTo(ApiVersionCondition apiVersionCondition, HttpServletRequest httpServletRequest) {
        return apiVersionCondition.getApiVersion() - this.apiVersion;
    }
}

3.使用RequestMappingHandlerMapping创建自定义的映射处理程序，根据Request参数匹配符合条件的处理程序

package com.yangjunbo.helloword.properties;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.mvc.condition.RequestCondition;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;

import java.lang.reflect.Method;

public class ApiRequestMappingHandlerMapping extends RequestMappingHandlerMapping {
    private static final String VERSION_FLAG = "{version}";

    private static RequestCondition<ApiVersionCondition> createCondition(Class<?> clazz) {
        RequestMapping classRequestMapping = clazz.getAnnotation(RequestMapping.class);
        if (classRequestMapping == null) {
            return null;
        }
        StringBuilder mappingUrlBuilder = new StringBuilder();
        if (classRequestMapping.value().length > 0) {
            mappingUrlBuilder.append(classRequestMapping.value()[0]);
        }
        String mappingUrl = mappingUrlBuilder.toString();
        if (!mappingUrl.contains(VERSION_FLAG)) {
            return null;
        }
        ApiVersion apiVersion = clazz.getAnnotation(ApiVersion.class);
        return apiVersion == null ? new ApiVersionCondition(1) : new ApiVersionCondition(apiVersion.value());
    }
    @Override
    protected RequestCondition<?> getCustomMethodCondition(Method method) {
        return createCondition(method.getClass());
    }
    @Override
    protected RequestCondition<?> getCustomTypeCondition(Class<?> handlerType) {
        return createCondition(handlerType);
    }
}

4.配置注册自定义的RequestMappingHandlerMapping

package com.yangjunbo.helloword.properties;

import org.springframework.boot.autoconfigure.web.servlet.WebMvcRegistrations;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;

@Configuration
public class WebMvcRegistrationsConfig implements WebMvcRegistrations {
    @Override
    public RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
        return new ApiRequestMappingHandlerMapping();
    }
}

5.创建测试接口

package com.yangjunbo.helloword.controller.v1;

import com.yangjunbo.helloword.common.JSONResult;
import com.yangjunbo.helloword.properties.ApiVersion;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

// V1 版本的接口定义
@RestController
@RequestMapping("api/{version}/order")
public class OrderV1Controller {
    @GetMapping("/delete/{orderId}")
    public JSONResult deleteOrderById(@PathVariable String orderId) {
        System.out.println("V1删除订单成功："+orderId);
        return JSONResult.ok("V1删除订单成功");
    }

    @GetMapping("/detail/{orderId}")
    public JSONResult queryOrderById(@PathVariable String orderId) {
        System.out.println("V1获取订单详情成功："+orderId);
        return JSONResult.ok("V1获取订单详情成功");
    }
}

package com.yangjunbo.helloword.controller.v2;

import com.yangjunbo.helloword.common.JSONResult;
import com.yangjunbo.helloword.properties.ApiVersion;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

// V2 版本的接口定义
@ApiVersion(2)
@RestController
@RequestMapping("api/{version}/order")
public class OrderV2Controller {
    @GetMapping("/detail/{orderId}")
    public JSONResult queryOrdearById(@PathVariable String orderId) {
        System.out.println("V2获取订单详情成功："+orderId);
        return JSONResult.ok("V2获取订单详情成功");
    }

    @GetMapping("/list")
    public JSONResult list() {
        System.out.println("V2,新增list订单列表接口");
        return JSONResult.ok(200,"V2,新增list订单列表接口");
    }
}

6.访问接口测试

以上验证情况说明Web API的版本控制配置成功，实现了旧版本的稳定和新版本的更新。
1）当请求正确的版本地址时，会自动匹配版本的对应接口。
2）当请求的版本大于当前版本时，默认匹配最新的版本。
3）高版本会默认继承低版本的所有接口。实现版本升级只关注变化的部分，没有变化的部分会自动平滑升级，这就是所谓的版本继承。
4）高版本的接口的新增和修改不会影响低版本。
这些特性使得在升级接口时，原有接口不受影响，只关注变化的部分，没有变化的部分自动平滑升级。这样使得Web API更加简洁，这就是实现Web API版本控制的意义所在。
参考书籍 《springboot从入门到实战-章为忠著》