由于springboot基于servlet3.0+,内嵌tomcat容器 因此无法像之前一样通过web.xml中配置Filter,本文基于springboot1.5.6
第一种
@WebFilter(filterName = "myFilter",urlPatterns = "/*")
public class MyFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
}
@Override
public void destroy() {
}
}
@SpringBootApplication
@EnableAutoConfiguration
@EnableWebMvc
@ServletComponentScan(basePackages = "com.fanyin.eghm")
public class EghmApplication {
public static void main(String[] args) {
SpringApplication.run(EghmApplication.class, args);
}
}
-
@ServletComponentScan所扫描的包路径必须包含该Filter
第二种
@Configuration
public class FilterConfig {
@Bean
public FilterRegistrationBean filterRegistrationBean(){
FilterRegistrationBean bean = new FilterRegistrationBean();
bean.setFilter(new MyFilter2());
bean.addUrlPatterns("/*");
return bean;
}
}
第三种
@Bean("proxyFilter")
public Filter filter (){
return new Filter() {
@Override
public void init(javax.servlet.FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
}
@Override
public void destroy() {
}
};
}
@Bean
public DelegatingFilterProxyRegistrationBean delegatingFilterProxyRegistrationBean(){
DelegatingFilterProxyRegistrationBean bean = new DelegatingFilterProxyRegistrationBean("proxyFilter");
bean.addUrlPatterns("/*");
return bean;
}
方法四
@Bean("myFilter")
public Filter filter (){
return new Filter() {
@Override
public void init(javax.servlet.FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
}
@Override
public void destroy() {
}
};
}
说明:
- 第二种和第三种类似,均实现了
AbstractFilterRegistrationBean接口,而该接口间接实现了ServletContextInitializer,springboot在启动容器后会查找实现该接口的bean,并调用onStartup()方法添加自定义的Filter,两则的区别DelegatingFilterProxyRegistrationBean通过传入的proxyFilter名字,在WebApplicationContext查找该Fillter Bean,并通过DelegatingFilterProxy生成基于该Bean的代理Filter对象,
而FilterRegistrationBean则是直接设置一个Filter,因此该Filter可以有spring容器管理,也可不用spring管理
注意:如果Filter声明为一个Bean,则不需要定义为FilterRegistrationBean,也会被spring发现并添加,就是方法四,该方式无法定义拦截规则等,默认全局,慎用
EmbeddedWebApplicationContext 容器启动后执行 springboot 2.0 变更为ServletWebServerApplicationContext
private void selfInitialize(ServletContext servletContext) throws ServletException {
prepareEmbeddedWebApplicationContext(servletContext);
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
ExistingWebApplicationScopes existingScopes = new ExistingWebApplicationScopes(
beanFactory);
WebApplicationContextUtils.registerWebApplicationScopes(beanFactory,
getServletContext());
existingScopes.restore();
WebApplicationContextUtils.registerEnvironmentBeans(beanFactory,
getServletContext());
for (ServletContextInitializer beans : getServletContextInitializerBeans()) {
beans.onStartup(servletContext);
}
}
getServletContextInitializerBeans() 会返回实现了ServletContextInitializer接口的集合,同时初始化一些数据,如下:
public ServletContextInitializerBeans(ListableBeanFactory beanFactory) {
this.initializers = new LinkedMultiValueMap<Class<?>, ServletContextInitializer>();
addServletContextInitializerBeans(beanFactory);
addAdaptableBeans(beanFactory);
List<ServletContextInitializer> sortedInitializers = new ArrayList<ServletContextInitializer>();
for (Map.Entry<?, List<ServletContextInitializer>> entry : this.initializers
.entrySet()) {
AnnotationAwareOrderComparator.sort(entry.getValue());
sortedInitializers.addAll(entry.getValue());
}
this.sortedList = Collections.unmodifiableList(sortedInitializers);
}
-
addAdaptableBeansaddServletContextInitializerBeans在调用onStartup()方法之前会添加Filter与Servlet,注意Filter与Servlet必须已经声明为Bean
- 第一种则最终也是采用第二种方式,区别就是在springboot启动时将扫描到的包路径作为入参传递给
ServletComponentRegisteringPostProcessor而该类实现了BeanFactoryPostProcessor接口,因此在BeanFactory初始化后,会调用postProcessBeanFactory()方法,在该方法中通过之前传入的包来扫描相应的类,并将@WebFilter的类由相应的处理器转换为FilterRegistrationBean
ServletComponentRegisteringPostProcessor
ServletComponentRegisteringPostProcessor(Set<String> packagesToScan) {
this.packagesToScan = packagesToScan;
}
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
throws BeansException {
if (isRunningInEmbeddedContainer()) {
ClassPathScanningCandidateComponentProvider componentProvider = createComponentProvider();
for (String packageToScan : this.packagesToScan) {
scanPackage(componentProvider, packageToScan);
}
}
}
private void scanPackage(
ClassPathScanningCandidateComponentProvider componentProvider,
String packageToScan) {
for (BeanDefinition candidate : componentProvider
.findCandidateComponents(packageToScan)) {
if (candidate instanceof ScannedGenericBeanDefinition) {
for (ServletComponentHandler handler : handlers) {
handler.handle(((ScannedGenericBeanDefinition) candidate),
(BeanDefinitionRegistry) this.applicationContext);
}
}
}
}
WebFilterHandler
WebFilterHandler() {
super(WebFilter.class);
}
@Override
public void doHandle(Map<String, Object> attributes,
ScannedGenericBeanDefinition beanDefinition,
BeanDefinitionRegistry registry) {
BeanDefinitionBuilder builder = BeanDefinitionBuilder
.rootBeanDefinition(FilterRegistrationBean.class);
builder.addPropertyValue("asyncSupported", attributes.get("asyncSupported"));
builder.addPropertyValue("dispatcherTypes", extractDispatcherTypes(attributes));
builder.addPropertyValue("filter", beanDefinition);
builder.addPropertyValue("initParameters", extractInitParameters(attributes));
String name = determineName(attributes, beanDefinition);
builder.addPropertyValue("name", name);
builder.addPropertyValue("servletNames", attributes.get("servletNames"));
builder.addPropertyValue("urlPatterns",
extractUrlPatterns("urlPatterns", attributes));
registry.registerBeanDefinition(name, builder.getBeanDefinition());
}
题外话
添加自定义Servlet 也可采用方法一
@WebServlet或者ServletRegistrationBean
添加自定义Listener也可以采用方法一@WebListener或者ServletListenerRegistrationBean,注意监听事件是泛型
