java控制api接口版本_SpringBoot实现API接口多版本支持的示例代码

好的，以下是一个简单的 Spring Boot 实现 API 接口多版本支持的示例代码。

首先，我们需要在 `pom.xml` 文件中添加 `spring-boot-starter-parent` 依赖和 `spring-boot-starter-web` 依赖。然后，在 `application.properties` 文件中添加一些配置：

# API 版本
api.version=v1

# v1 版本 API 的 URL 前缀
api.v1.path=/api/v1

# v2 版本 API 的 URL 前缀
api.v2.path=/api/v2

然后，我们创建一个 `VersionHandlerInterceptor` 拦截器来处理 API 版本：

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class VersionHandlerInterceptor implements HandlerInterceptor {

    private static final String API_VERSION_HEADER = "Api-Version";
    private static final String DEFAULT_API_VERSION = "v1";

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        String apiVersion = request.getHeader(API_VERSION_HEADER);
        if (apiVersion == null) {
            apiVersion = DEFAULT_API_VERSION;
        }
        request.setAttribute("apiVersion", apiVersion);
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    }
}

该拦截器从请求头中获取 API 版本，如果没有指定则默认为 `v1`，并将其存储到请求属性中。

接下来，我们创建一个 `ApiVersionRequestMappingHandlerMapping` 请求映射处理器来支持多版本 API：

import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.mvc.condition.RequestCondition;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;

import java.lang.reflect.Method;

public class ApiVersionRequestMappingHandlerMapping extends RequestMappingHandlerMapping {

    private static final String API_VERSION_ATTRIBUTE = "apiVersion";

    @Override
    protected RequestCondition<ApiVersionRequestCondition> getCustomTypeCondition(Class<?> handlerType) {
        ApiVersion apiVersion = AnnotationUtils.findAnnotation(handlerType, ApiVersion.class);
        return createRequestCondition(apiVersion);
    }

    @Override
    protected RequestCondition<ApiVersionRequestCondition> getCustomMethodCondition(Method method) {
        ApiVersion apiVersion = AnnotationUtils.findAnnotation(method, ApiVersion.class);
        return createRequestCondition(apiVersion);
    }

    private RequestCondition<ApiVersionRequestCondition> createRequestCondition(ApiVersion apiVersion) {
        return apiVersion == null ? null : new ApiVersionRequestCondition(apiVersion.value());
    }

    private static class ApiVersionRequestCondition implements RequestCondition<ApiVersionRequestCondition> {

        private final String apiVersion;

        public ApiVersionRequestCondition(String apiVersion) {
            this.apiVersion = apiVersion;
        }

        @Override
        public ApiVersionRequestCondition combine(ApiVersionRequestCondition other) {
            return new ApiVersionRequestCondition(other.apiVersion);
        }

        @Override
        public ApiVersionRequestCondition getMatchingCondition(HttpServletRequest request) {
            String apiVersion = (String) request.getAttribute(API_VERSION_ATTRIBUTE);
            if (!StringUtils.hasText(apiVersion)) {
                apiVersion = DEFAULT_API_VERSION;
            }
            return new ApiVersionRequestCondition(apiVersion.equals(this.apiVersion) ? this.apiVersion : null);
        }

        @Override
        public int compareTo(ApiVersionRequestCondition other, HttpServletRequest request) {
            String apiVersion = (String) request.getAttribute(API_VERSION_ATTRIBUTE);
            if (!StringUtils.hasText(apiVersion)) {
                apiVersion = DEFAULT_API_VERSION;
            }
            return apiVersion.compareTo(other.apiVersion);
        }
    }
}

该请求映射处理器通过 `ApiVersion` 注解获取 API 版本，然后根据 API 版本创建一个自定义请求条件 `ApiVersionRequestCondition`。

最后，我们可以使用 `@ApiVersion` 注解来指定 API 版本：

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@ApiVersion("v1")
public class UserController {

    @GetMapping("/users")
    public String getUsers() {
        return "v1 users";
    }
}

根据上述示例代码，我们可以轻松实现 Spring Boot 的 API 接口多版本支持。