已被CORS策略阻止：请求的资源上没有'Access-Control-Allow-Origin'标头 (使用Access-Control-Allow-Origin解决跨域)

问题：已被CORS策略阻止：请求的资源上没有'Access-Control-Allow-Origin'标头（跨域请求失败）

解决方法：使用过滤器设置Access-Control-Allow-Origin解决跨域请求

第一步： 建立过滤器

package com.ljw.filter;
 
import java.io.IOException;
 
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;
 
public class SimpleCORSFilter implements Filter {
 
	@Override
	public void destroy() {
 
	}
 
	@Override
	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
		HttpServletResponse response = (HttpServletResponse) res;  
		// 指定容许其余域名访问 
		response.setHeader("Access-Control-Allow-Origin", "*"); // 容许全部
		// response.setHeader("Access-Control-Allow-Origin", "http://127.0.0.1, http://locahost"); // 容许白名单IP
		// 响应类型
		response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");  
		// 预检请求的结果缓存60分钟
		response.setHeader("Access-Control-Max-Age", "3600");  
		// 响应头设置 
		response.setHeader("Access-Control-Allow-Headers", "x-requested-with");  
		chain.doFilter(req, res);  
	}
 
	@Override
	public void init(FilterConfig arg0) throws ServletException {
 
	}
}

第二步：web.xml 配置过滤器

<filter>  
    <filter-name>cors</filter-name>  
    <filter-class>com.ljw.filter.SimpleCORSFilter</filter-class>  
  </filter>  
  <filter-mapping>  
    <filter-name>cors</filter-name>  
    <url-pattern>/*</url-pattern>  
  </filter-mapping>

————————————————
版权声明：本文为CSDN博主「@不白」的原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处连接及本声明。
原文连接：https://blog.csdn.net/qq_39726772/article/details/88973362