springboot 练习

搭建好一个springboot项目 ，第一件事就是要做前后端的交互

1.遇到第一个问题，跨域的问题，添加拦截器

package com.practice.springboot.util;

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

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

public class HttpInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception{

        String origin = httpServletRequest.getHeader("Origin");
        httpServletResponse.setHeader("Access-Control-Allow-Origin", origin);
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "*");
        httpServletResponse.setHeader("Access-Control-Allow-Headers","Origin,Content-Type,Accept,token,X-Requested-With");
        httpServletResponse.setHeader("Access-Control-Allow-Credentials", "true");

        return true;
    }



    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {

        String origin = httpServletRequest.getHeader("Origin");
        httpServletResponse.setHeader("Access-Control-Allow-Origin", origin);
        //如果此处不用post去请求，前台用post会报错
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "post");
        httpServletResponse.setHeader("Access-Control-Allow-Headers","Origin,Content-Type,Accept,token,X-Requested-With");
        httpServletResponse.setHeader("Access-Control-Allow-Credentials", "true");
    }
    //其他postHandle,afterCompletion空继承

}

package com.practice.springboot.util;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

@Configuration
public class MvcConfig extends WebMvcConfigurationSupport {

    @Override
    public void addInterceptors(InterceptorRegistry registry){
        registry.addInterceptor(new HttpInterceptor()).addPathPatterns("/**");
    }

}

2.第二个问题

 Could not resolve view with name 'user/show' in servlet with name 'dispatcherServlet'

这是因为没有返回视图，在Controller里，访问的方法上添加注解

@ResponseBody