跨域请求错误

场景

在下新手，用优快云记个笔记，记录每个踩过的坑，方便日后复制粘贴。
我用多个springnoot项目互相请求，服务A的地址是localhost:8081，服务B地址是localhost:8082，直接从A写一个ajax请求B会报错，因为跨域了。

解决方案

解决方案好几种，我比较喜欢这一种， 在服务B加个filter ,代码如下：

import org.springframework.stereotype.Component;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Component
public class CorsFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletResponse response=(HttpServletResponse)servletResponse;
        response.addHeader("Access-Control-Allow-Credentials","true");
        response.addHeader("Access-Control-Allow-Origin","*");
        response.addHeader("Access-Control-Allow-Methods","*");
        response.addHeader("Access-Control-Allow-Headers","Content-Type,X-CAF-Authorization-Token,sessionToken,X-TOKEN");
        if (((HttpServletRequest) servletRequest).getMethod().equals("OPTIONS")) {
            response.getWriter().println("ok");
            return;
        }
        filterChain.doFilter(servletRequest, response);
    }
    //重写init和destroy方法，否则tomcat启动失败
	@Override
    public void init(FilterConfig filterConfig) throws ServletException {    }

    @Override
    public void destroy() {    }
}