SpringBoot获取HttpServletRequest、HttpServletResponse的三种方式

目录

• 1、直接在Controller层方法参数上获取
• 2、通过@Autowired注入
• 3、通过RequestContextHolder获取

  1、直接在Controller层方法参数上获取

  仅仅适用在controller方法上。当Spring接收到HTTP请求时，会寻找一个合适的方法来处理该请求。如果该方法参数上标注了@RequestMapping或@Get、@Post等注解，Spring就会将HttpServletRequest对象注入到该参数中。

  @RestControllerpublic class Controller {    @RequestMapping("/test")    public String test(HttpServletRequest request,HttpServletResponse response) {        return "success";    }}

  2、通过@Autowired注入

  适用于所有的bean

  @Autowiredprivate HttpServletRequest request;@Autowiredprivate HttpServletResponse response;@RequestMapping("/test")public String test() {    Enumeration headerNames = request.getHeaderNames();    response.setHeader("header","header_value");    return "success";}

  通过调试可以看到，注入的Reques是一个代理类，而这个被代理的目标由RequestObjectFactory.getObject() 获取

  我们再看一下RequestObjectFactory.getObject() 的方法，最终还是走到了RequestContextHolder.getRequestAttributes()方法

  private static class RequestObjectFactory implements ObjectFactory, Serializable {@Overridepublic ServletRequest getObject() {return currentRequestAttributes().getRequest();}@Overridepublic String toString() {return "Current HttpServletRequest";}}private static ServletRequestAttributes currentRequestAttributes() {RequestAttributes requestAttr = RequestContextHolder.currentRequestAttributes();if (!(requestAttr instanceof ServletRequestAttributes)) {throw new IllegalStateException("Current request is not a servlet request");}return (ServletRequestAttributes) requestAttr;}

  3、通过RequestContextHolder获取

  适用于所有的方法，spring会通过RequestContextHolder.setRequestAttributes方法将RequestAttributes设置到ThreadLocal中。

  ServletRequestAttributes attr = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();HttpServletRequest request = attr.getRequest();HttpServletResponse response = attr.getResponse();