CORS是一个W3C标准，全称是”跨域资源共享”（Cross-origin resource sharing）。 它允许浏览器向跨源服务器，发出XMLHttpRequest请求，从而克服了AJAX只能同源使用的限制。

1.加入CROS依赖的包

<dependency>
    <groupId>com.thetransactioncompany</groupId>
    <artifactId>java-property-utils</artifactId>
    <version>1.10</version>
</dependency>
<dependency>
    <groupId>com.thetransactioncompany</groupId>
    <artifactId>cors-filter</artifactId>
    <version>1.9.1</version>
</dependency>

2. web.xml 加入CORSFilter

<filter>
    <filter-name>CORS</filter-name>
        <filter-class>com.thetransactioncompany.cors.CORSFilter</filter-class>
        <init-param>
            <param-name>cors.allowOrigin</param-name>
            <param-value>*</param-value>
        </init-param>
        <init-param>
            <param-name>cors.supportedMethods</param-name>
            <param-value>GET, POST, HEAD, PUT, DELETE</param-value>
        </init-param>
        <init-param>
            <param-name>cors.supportedHeaders</param-name>
            <param-value>Accept, Origin, X-Requested-With, Content-Type,
                Last-Modified</param-value>
        </init-param>
        <init-param>
            <param-name>cors.exposedHeaders</param-name>
            <param-value>Set-Cookie</param-value>
        </init-param>
        <init-param>
            <param-name>cors.supportsCredentials</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>CORS</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</fitler>

注意点

CORSFilter 放在最上边，最先被加载，不然无效