解决No 'Access-Control-Allow-Origin' header is present on the requested resource.跨域问题

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跨域错误

错误原因

解决方法

在后台写一个filter过滤器来改写请求头header

CrossFilter.java

public class CrossFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        HttpServletRequest request = (HttpServletRequest)servletRequest;

        String origin = request.getHeader("Origin");
        response.setHeader("Access-Control-Allow-Origin", origin);
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Headers", "x-requested-with,Authorization");
        response.setHeader("Access-Control-Allow-Credentials", "true");
        String method = request.getMethod();
        if(method.equalsIgnoreCase("OPTIONS")){
            servletResponse.getOutputStream().write("Success".getBytes("utf-8"));
        }else{
            filterChain.doFilter(servletRequest, servletResponse);
        }
    }

    @Override
    public void destroy() {

    }
}

备注:

在web.xml添加代码

<filter>
    <filter-name>crossFilter</filter-name>
    <filter-class>xxx.xxx.CrossFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>crossFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>