cors跨域 可以让js直接访问接口而不需要jsop等跨域操作

cors原理是在请求头的前面加上一个origin的参数 然后浏览器会允许js跨域

maven:

<dependency>
<groupId>com.thetransactioncompany</groupId>
<artifactId>cors-filter</artifactId>
<version>2.5</version>
</dependency>

web.xml配置（确保filter在web.xml配置的顺序正确 可能会被先生效的其他组件覆盖 所以需要配置在最上面）：

<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>