Cors跨域请求，配置Access-Control-Allow-Origin："*"，无效解决方案
由于应用需要跨域请求数据，博主在JDK8、Tomcat7.0的cors可以配置Access-Control-Allow-Origin："*"，但是我按照文档配置以后却没有生效，一度怀疑是tomcat或者jdk的问题，最后想起来web.xml是按照从前往后的顺序加载的。解决方案：是filter位置的问题，你把整个放到第一个filter的位置就可以了。给出web.xml:
<?xml version="1.0"encoding="UTF-8"?>
<web-app id="WebApp_ID"version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2eehttp://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<display-name>och</display-name>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring/spring-*.xml</param-value>
</context-param>
<listener>
<context-param>
<param-name>webAppRootKey</param-name>
<param-value>och.root</param-value>
</context-param>
<listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
</listener>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!--启用Spring的scope='request' -->
<listener>
<listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
</listener>
<!--CORS Filter -->
<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>
<filter>
<filter-name>characterEncodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>ForceEncoding</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>characterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>control</filter-name>
<filter-class>com.cmos.core.filter.IControlRequestFilter</filter-class>
<init-param>
<param-name>controlRequestImpl</param-name>
<param-value>com.cmos.och.control.impl.ControlRequestImpl</param-value>
</init-param>
<init-param>
<param-name>controlFilePath</param-name>
<param-value>config/control.xml</param-value>
</init-param>
<init-param><!--Internationalization config -->
<param-name>locale</param-name>
<param-value>zh_CN</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>control</filter-name>
<url-pattern>/front/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>struts2</filter-name>
<filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>struts2</filter-name>
<url-pattern>/front/*</url-pattern>
</filter-mapping>
</web-app>