在Servlet Filter中使用Spring容器

定義一個filter, 實現ApplicationContextAware接口：

public class CacheFilter implements Filter, ApplicationContextAware {
private static ApplicationContext ctx; // 必須聲明為static

@Override
public void init(FilterConfig config) throws ServletException {
}

@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

filterChain.doFilter(servletRequest, servletResponse);

}

@Override
public void destroy() {

}

@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
CacheFilter.ctx = applicationContext; // 保存spring容器到static變量中
}

然後，在spring配置文件中配置該filter，使之成為容器管理的bean:

<beans:bean id="cacheFilter" class="com.fh.taolijie.servlet.CacheFilter" />

最後，在web.xml中聲明過濾器：

<filter>
<filter-name>Cache Filter</filter-name>
<filter-class>com.fh.taolijie.servlet.CacheFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>Cache Filter</filter-name>
<servlet-name>appServlet</servlet-name>
</filter-mapping>

這時，我們就可以在doFilter()方法中直接通過ApplicationContext檢索需要的bean了：

StringRedisTemplate redis = (StringRedisTemplate)ctx.getBean("redisTemplate");