Java | ssm中通过自定义注解实现RESTful风格接口版

作者: l王小一 | 来源:发表于2018-10-31 17:32 被阅读0次

Java | ssm中通过自定义注解实现RESTful风格接口版
SSM集成
Spring+SpringMVC+MyBatis整合进阶篇（四）
简单实现自定义注解
注解反射动态代理的简单学习
SpringMVC之Controller及RestFul
注解的使用
@interface自定义注解的语法
SpringBoot之自定义注解（基于BeanPostProce
Java语言高级特性--注解与反射

什么是RESTful?

简单说就是一种接口的风格、规范。
详细的介绍请戳下面链接
https://www.runoob.com/w3cnote/restful-architecture.html

为什么要用RESTful？

为了使接口使用起来更方便、实现时代码更简洁
之前做java web接触的form表单提交方式通常只有两种get & post
RESTful就是根据提交方式去进行操作

以前的请求路径
https://localhost:8080/springdemo/getUser
https://localhost:8080/springdemo/deleteUser

使用RESTful后
GET   https://localhost:8080/springdemo/user
DELETE   https://localhost:8080/springdemo/user

也可以进行版本管理
https://localhost:8080/springdemo/v1/user
https://localhost:8080/springdemo/v2/user

通过自定义注解实现版本管理

1.自定义注解

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Mapping
public @interface ApiVersion {
    /*
     * api version code
     */
    int value();
}

2.自定义筛选条件

public class ApiVesrsionCondition implements RequestCondition<ApiVesrsionCondition> {
    
    // 路径中版本的前缀， 这里用 /v[1-9]/的形式
    private final static Pattern VERSION_PREFIX_PATTERN = Pattern.compile("v(\\d+)/");

    private int apiVersion;

    public ApiVesrsionCondition(int apiVersion){
        this.apiVersion = apiVersion;
    }

    /*
     * 将不同的筛选条件合并
     * 
     */
    @Override
    public ApiVesrsionCondition combine(ApiVesrsionCondition other) {
        return new ApiVesrsionCondition(other.getApiVersion());
    }
    
    /*
     * 根据request查找匹配到的筛选条件
     * 
     */
    @Override
    public ApiVesrsionCondition getMatchingCondition(HttpServletRequest request) {
        System.out.println(request.getRequestURI());
        Matcher m = VERSION_PREFIX_PATTERN.matcher(request.getRequestURI());
        if(m.find()){
            Integer version = Integer.valueOf(m.group(1));
            if(version >= this.apiVersion) // 如果请求的版本号大于配置版本号， 则返回当前最大版本
                return this;
        }
        return null;

    }

    /*
     * 实现不同条件类的比较，从而实现优先级排序
     * 
     */
    @Override
    public int compareTo(ApiVesrsionCondition other, HttpServletRequest request) {
        return other.getApiVersion() - this.apiVersion;
    }
    
    
    public int getApiVersion() {
        return apiVersion;
    }
}

3.重写RequestMappingHandlerMapping 的映射

public class CustomRequestMappingHandlerMapping extends RequestMappingHandlerMapping {
    
    @Override   
    protected RequestCondition<ApiVesrsionCondition> getCustomTypeCondition(Class<?> handlerType) {
        ApiVersion apiVersion = AnnotationUtils.findAnnotation(handlerType, ApiVersion.class);
        return createCondition(apiVersion);
    }

    @Override  
    protected RequestCondition<ApiVesrsionCondition> getCustomMethodCondition(Method method) {
        ApiVersion apiVersion = AnnotationUtils.findAnnotation(method, ApiVersion.class);
        return createCondition(apiVersion);
    }
    //实例化RequestCondition
    private RequestCondition<ApiVesrsionCondition> createCondition(ApiVersion apiVersion) {
        return apiVersion == null ? null : new ApiVesrsionCondition(apiVersion.value());
    }

}

这样做是为了在@RequestMapping注解中的整体url可以找到我们自定义的注解

4.使我们自定义的拦截器生效

@Configuration
public class WebConfig extends WebMvcConfigurationSupport{
    @Override
    @Bean
    public RequestMappingHandlerMapping requestMappingHandlerMapping() {
        RequestMappingHandlerMapping handlerMapping = new CustomRequestMappingHandlerMapping();
        handlerMapping.setOrder(0);
        handlerMapping.setInterceptors(getInterceptors());
        return handlerMapping;
    }
}