SpringBoot入门到精通（二十一）如何优雅的设计 RESTful API 接口版本号，实现 API 版本控制！

package com.weiz.config;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
 * API版本控制注解
*/
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface ApiVersion {
    /**
     * @return 版本号
     */
    int value() default 1;
}

package com.weiz.config;
import org.springframework.web.servlet.mvc.condition.RequestCondition;
import javax.servlet.http.HttpServletRequest;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
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) {
                return this;
            }
        }
        return null;
    }
    @Override
    public int compareTo(ApiVersionCondition apiVersionCondition, HttpServletRequest httpServletRequest) {
        return apiVersionCondition.getApiVersion() - this.apiVersion;
    }
}

package com.weiz.config;
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);
    }
}

package com.weiz.config;
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();
    }
}

@RequestMapping("api/{version}/user")
@RestController
public class UserV1Controller {
    @GetMapping("/test")
    public String test() {
        return "version1";
    }
    @GetMapping("/extend")
    public String extendTest() {
        return "user v1 extend";
    }
}
UserV2Controller
@RequestMapping("api/{version}/user")
@RestController
@ApiVersion(2)
public class UserV2Controller {
    @GetMapping("/test")
    public String test() {
        return "user v2 test";
    }
}