前后端代码分离跨域问题

前端ajax访问后端：(主要关注url路径)

<script type="text/javascript">
        $(function(){
        	  $.ajax({
      			cache: false,
      			async: false,
      			type: "GET",
      			dataType: "json",
      			//data: {method: "validateAjaxname", username: username},
      			url: "http://localhost:8080/getdata",
      			success: function(data) {
      				 var html;
      	             for( var i = 0; i < data.length; i++ ) {
      	                 html += "<tr>";
      	                 html +=     "<td>" + data[i].name + "</td>"
      	                 html +=     "<td>" + data[i].url + "</td>"
      	                 html +=     "<td>" + data[i].type + "</td>"
      	                 html += "</tr>";
      	             }
      	             $("#J_TbData").html(html);
      			}
      		});
        	
        });
    </script>

前端页面访问不到后端数据，跨域问题报错如下：

解决办法：

https://www.cnblogs.com/zishu/p/10727230.html

过滤器

import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
 
public class CrosFilter implements javax.servlet.Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
 
    }
 
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletResponse res = (HttpServletResponse) servletResponse;
        //*号表示对所有请求都允许跨域访问
        res.addHeader("Access-Control-Allow-Origin", "*");
        res.addHeader("Access-Control-Allow-Methods", "*");
        filterChain.doFilter(servletRequest, servletResponse);
    }
 
    @Override
    public void destroy() {
 
    }
}

@SpringBootApplication
@MapperScan("com.mybatisplus.springboot")
public class MybatisPlusSpringbootApplication {

	public static void main(String[] args) {
		SpringApplication.run(MybatisPlusSpringbootApplication.class, args);
	}
	
    /**
     * 配置跨域访问的过滤器
     * @return
     */
	@Bean
    public FilterRegistrationBean registerFilter(){
        FilterRegistrationBean bean = new FilterRegistrationBean();
        bean.addUrlPatterns("/*");
        bean.setFilter(new CrosFilter());
        return bean;
    }
}