代码重构之函数式编程

近期接手的项目发现controller中的代码结构都是一样的，但是重复性代码太多。如下所示：

    //产生实例对象
    private ABusiness aService = new ABusiness();
    private BBusiness bService = new BBusiness();
    private CBusiness cService = new CBusiness();

    @PostMapping("/A")
    public void doA(AForm form, HttpServletRequest request, HttpServletResponse response) {
        try{
            //验签
            verifyHeader(form,request);
            //执行业务逻辑
            String result = aService.doA(form);
            getResponse(response, result);
        } catch (Exception e) {
            writeUnauthorizedResponse(e,response);
        }
    }
    @PostMapping("/B")
    public void doB(BForm form, HttpServletRequest request, HttpServletResponse response) {
        try{
            //验签
            verifyHeader(form,request);
            //执行业务逻辑
            String result = bService.doB(form);
            getResponse(response, result);
        } catch (Exception e) {
            writeUnauthorizedResponse(e,response);
        }
    }
    @PostMapping("/C")
    public void doC(CForm form, HttpServletRequest request, HttpServletResponse response) {
        try{
            //验签
            verifyHeader(form,request);
            //执行业务逻辑
            String result = cService.doC(form);
            getResponse(response, result);
        } catch (Exception e) {
            writeUnauthorizedResponse(e,response);
        }
    }

    private void verifyHeader(Object form, HttpServletRequest request) {
        //验签处理
    }
    private void getResponse(HttpServletResponse response, String result) {
        //回复逻辑处理
    }
    private void writeUnauthorizedResponse(Exception e, HttpServletResponse response) {
        //异常处理
    }
}

类似如上的代码，每新增一个接口，开发同学都是直接复制，然后修改其中的业务处理那块代码如doC,doA 但是对于verifyHeader，getResponse，writeUnauthorizedResponse这些方法其实都是共用的，可以考虑抽出。

    public void executeBusiness(Object form, Supplier supplier) {
        HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
        HttpServletResponse response = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getResponse();
        try{
            //验签
            verifyHeader(form,request);
            //执行业务逻辑
            getResponse(response, supplier.get());
        } catch (Exception e) {
            writeUnauthorizedResponse(e,response);
        }
    }

    public void doA(AForm form) {
        executeBusiness(form, () -> aService.doA(form));
    }
    public void doB(BForm form) {
        executeBusiness(form, () -> bService.doB(form));
    }
    public void doC(CForm form) {
        executeBusiness(form, () -> cService.doC(form));
    }

这样代码看起来会简洁很多。JAVA8提供了许多函数式方法如Function，Predicate等，可以多尝试使用。