技术标签： filter 【spring系列】 servlet registration initializer
springboot提供在Servlet 3.0+环境中用于编码方式配置ServletContext的接口，此接口（ServletContextInitializer）主要被RegistrationBean抽象类实现用于往ServletContext容器中注册Servlet、Filter或者Listener。这些实现了此接口的Bean的生命周期将会交给Spring容器管理，而不会交给Servlet容器。
@FunctionalInterface
public interface ServletContextInitializer {
/**
* 使用初始化所需要的任何servlet、Filter、Listener上下文参数及所需要的参数进行初始化ServletContext
* @param servletContext 将要初始化的上下文
* @throws ServletException 抛出发生的异常信息
*/
void onStartup(ServletContext servletContext) throws ServletException;
}
public abstract class RegistrationBean implements ServletContextInitializer, Ordered {
private static final Log logger = LogFactory.getLog(RegistrationBean.class);
//注册bean的优先级
private int order = Ordered.LOWEST_PRECEDENCE;
//指示注册是否已经启用的标记
private boolean enabled = true;
@Override
public final void onStartup(ServletContext servletContext) throws ServletException {
//获取注册bean的描述信息
String description = getDescription();
//判定是否开启注册功能，否则打印info日志并且直接返回
if (!isEnabled()) {
logger.info(StringUtils.capitalize(description) + " was not registered (disabled)");
return;
}
//调用抽象的注册方法
register(description, servletContext);
}
/**
* 返回注册的描述说明
*/
protected abstract String getDescription();
/**
* 在servlet上下文中注册这个bean.
* @param description 正在注册项的描述
* @param servletContext the servlet context
*/
protected abstract void register(String description, ServletContext servletContext);
/**
* 指示注册是否已经启用的标记
*/
public void setEnabled(boolean enabled) {
this.enabled = enabled;
}
/**
* 返回注册是否一起用的标记boolean值
*/
public boolean isEnabled() {
return this.enabled;
}
/**
* 设置注册bean的优先级顺序
*/
public void setOrder(int order) {
this.order = order;
}
/**
* 获取注册bean的优先级顺序
*/
@Override
public int getOrder() {
return this.order;
}
}
public abstract class DynamicRegistrationBean<D extends Registration.Dynamic> extends RegistrationBean {
private static final Log logger = LogFactory.getLog(RegistrationBean.class);
//注册的名称，如果没有指定，将使用bean的名称
private String name;
//是否支持异步注册
private boolean asyncSupported = true;
private Map<String, String> initParameters = new LinkedHashMap<>();
/**
* 设置注册的名称，如果没有指定，将使用bean的名称
*/
public void setName(String name) {
Assert.hasLength(name, "Name must not be empty");
this.name = name;
}
/**
* 如果此操作支持异步注册，则支持异步集，如果未指定，则默认为true
*/
public void setAsyncSupported(boolean asyncSupported) {
this.asyncSupported = asyncSupported;
}
/**
* 判定当前注册是否支持异步注册
*/
public boolean isAsyncSupported() {
return this.asyncSupported;
}
/**
* 为此注册设置init参数，调用此方法将替换任何现有的init参数
*/
public void setInitParameters(Map<String, String> initParameters) {
Assert.notNull(initParameters, "InitParameters must not be null");
this.initParameters = new LinkedHashMap<>(initParameters);
}
/**
* 返回注册的初始化参数
*/
public Map<String, String> getInitParameters() {
return this.initParameters;
}
/**
* 添加一个init参数，用相同的名称替换任何现有的参数
* @param name 初始化参数名
* @param value 初始化参数值
*/
public void addInitParameter(String name, String value) {
Assert.notNull(name, "Name must not be null");
this.initParameters.put(name, value);
}
//注册方法的具体实现
@Override
protected final void register(String description, ServletContext servletContext) {
//调用具体的注册方法
D registration = addRegistration(description, servletContext);
if (registration == null) {
logger.info(StringUtils.capitalize(description) + " was not registered (possibly already registered?)");
return;
}
//配置注册结果
configure(registration);
}
//注册具体动作抽象方法
protected abstract D addRegistration(String description, ServletContext servletContext);
//注册结果及设置参数
protected void configure(D registration) {
registration.setAsyncSupported(this.asyncSupported);
if (!this.initParameters.isEmpty()) {
registration.setInitParameters(this.initParameters);
}
}
/**
* 推断此注册的名称，将返回用户指定的名称或回退到基于约定的命名
*/
protected final String getOrDeduceName(Object value) {
return (this.name != null) ? this.name : Conventions.getVariableName(value);
}
}
public class ServletRegistrationBean<T extends Servlet> extends DynamicRegistrationBean<ServletRegistration.Dynamic> {
//默认路径匹配
private static final String[] DEFAULT_MAPPINGS = {
"/*" };
//将要注册的servlet
private T servlet;
//映射的URL路由模式集合
private Set<String> urlMappings = new LinkedHashSet<>();
//如果省略了URL映射，则应将其替换为"/*"
private boolean alwaysMapUrl = true;
//启动优先级
private int loadOnStartup = -1;
//要设置的配置
private MultipartConfigElement multipartConfig;
/**
* 创建一个ServletRegistrationBean实例对象
*/
public ServletRegistrationBean() {
}
/**
* 创建一个ServletRegistrationBean实例对象，并且制定servlet和URL映射参数
*/
public ServletRegistrationBean(T servlet, String... urlMappings) {
this(servlet, true, urlMappings);
}
/**
* 创建一个ServletRegistrationBean实例对象，并且制定servlet、如果省略URL则使用"/*"替换,和URL映射参数
* @param servlet the servlet being mapped
* @param alwaysMapUrl if omitted URL mappings should be replaced with '/*'
* @param urlMappings the URLs being mapped
*/
public ServletRegistrationBean(T servlet, boolean alwaysMapUrl, String... urlMappings) {
Assert.notNull(servlet, "Servlet must not be null");
Assert.notNull(urlMappings, "UrlMappings must not be null");
this.servlet = servlet;
this.alwaysMapUrl = alwaysMapUrl;
this.urlMappings.addAll(Arrays.asList(urlMappings));
}
/**
* Sets the servlet to be registered.
* @param servlet the servlet
*/
public void setServlet(T servlet) {
Assert.notNull(servlet, "Servlet must not be null");
this.servlet = servlet;
}
/**
* 返回正在注册的servlet
*/
public T getServlet() {
return this.servlet;
}
/**
* 设置servlet的URL映射，如果未指定，映射将默认为"/",这将替换以前指定的任何映射
*/
public void setUrlMappings(Collection<String> urlMappings) {
Assert.notNull(urlMappings, "UrlMappings must not be null");
this.urlMappings = new LinkedHashSet<>(urlMappings);
}
/**
* 返回注册的servlet的映射集合
* @return the urlMappings
*/
public Collection<String> getUrlMappings() {
return this.urlMappings;
}
/**
* 添加注册的servlet的url映射
* @param urlMappings the mappings to add
* @see #setUrlMappings(Collection)
*/
public void addUrlMappings(String... urlMappings) {
Assert.notNull(urlMappings, "UrlMappings must not be null");
this.urlMappings.addAll(Arrays.asList(urlMappings));
}
/**
* 设置loadOnStartup方法的优先级
*/
public void setLoadOnStartup(int loadOnStartup) {
this.loadOnStartup = loadOnStartup;
}
/**
* 设置注册servlet的配置
*/
public void setMultipartConfig(MultipartConfigElement multipartConfig) {
this.multipartConfig = multipartConfig;
}
/**
* 获取servlet的配置
*/
public MultipartConfigElement getMultipartConfig() {
return this.multipartConfig;
}
//获取注册servlet的描述
@Override
protected String getDescription() {
Assert.notNull(this.servlet, "Servlet must not be null");
return "servlet " + getServletName();
}
//核心，向ServletContext注册servlet对象
@Override
protected ServletRegistration.Dynamic addRegistration(String description, ServletContext servletContext) {
String name = getServletName();
return servletContext.addServlet(name, this.servlet);
}
/**
* 配置注册配置
*/
@Override
protected void configure(ServletRegistration.Dynamic registration) {
super.configure(registration);
String[] urlMapping = StringUtils.toStringArray(this.urlMappings);
if (urlMapping.length == 0 && this.alwaysMapUrl) {
urlMapping = DEFAULT_MAPPINGS;
}
if (!ObjectUtils.isEmpty(urlMapping)) {
registration.addMapping(urlMapping);
}
registration.setLoadOnStartup(this.loadOnStartup);
if (this.multipartConfig != null) {
registration.setMultipartConfig(this.multipartConfig);
}
}
/**
* 获取将被注册的servlet的名字
* @return the servlet name
*/
public String getServletName() {
return getOrDeduceName(this.servlet);
}
@Override
public String toString() {
return getServletName() + " urls=" + getUrlMappings();
}
}
public abstract class AbstractFilterRegistrationBean<T extends Filter> extends DynamicRegistrationBean<Dynamic> {
//默认的URL映射路径
private static final String[] DEFAULT_URL_MAPPINGS = {
"/*" };
private Set<ServletRegistrationBean<?>> servletRegistrationBeans = new LinkedHashSet<>();
private Set<String> servletNames = new LinkedHashSet<>();
private Set<String> urlPatterns = new LinkedHashSet<>();
private EnumSet<DispatcherType> dispatcherTypes;
private boolean matchAfter = false;
/**
* 创建AbstractFilterRegistrationBean实例对象，参数为ServletRegistrationBean集合
*/
AbstractFilterRegistrationBean(ServletRegistrationBean<?>... servletRegistrationBeans) {
Assert.notNull(servletRegistrationBeans, "ServletRegistrationBeans must not be null");
Collections.addAll(this.servletRegistrationBeans, servletRegistrationBeans);
}
/**
* 设置ServletRegistrationBean，过滤器将会针对其进行注册
*/
public void setServletRegistrationBeans(Collection<? extends ServletRegistrationBean<?>> servletRegistrationBeans) {
Assert.notNull(servletRegistrationBeans, "ServletRegistrationBeans must not be null");
this.servletRegistrationBeans = new LinkedHashSet<>(servletRegistrationBeans);
}
/**
* 返回Filter简要根据ServletRegistrationBean集合对象进行注册的ServletRegistrationBean集合
*/
public Collection<ServletRegistrationBean<?>> getServletRegistrationBeans() {
return this.servletRegistrationBeans;
}
/**
* 添加ServletRegistrationBean对象
*/
public void addServletRegistrationBeans(ServletRegistrationBean<?>... servletRegistrationBeans) {
Assert.notNull(servletRegistrationBeans, "ServletRegistrationBeans must not be null");
Collections.addAll(this.servletRegistrationBeans, servletRegistrationBeans);
}
/**
* 设置过滤器将注册的servlet名称，这将替换以前指定的任何servlet名称
*/
public void setServletNames(Collection<String> servletNames) {
Assert.notNull(servletNames, "ServletNames must not be null");
this.servletNames = new LinkedHashSet<>(servletNames);
}
/**
* 返回用于注册过滤器的servlet名称的可变集合
*/
public Collection<String> getServletNames() {
return this.servletNames;
}
/**
* 为Filter添加servlet名称
*/
public void addServletNames(String... servletNames) {
Assert.notNull(servletNames, "ServletNames must not be null");
this.servletNames.addAll(Arrays.asList(servletNames));
}
/**
* 设置将根据其注册Filter的URL模式，这将替换以前指定的任何URL模式
*/
public void setUrlPatterns(Collection<String> urlPatterns) {
Assert.notNull(urlPatterns, "UrlPatterns must not be null");
this.urlPatterns = new LinkedHashSet<>(urlPatterns);
}
/**
* 返回一个URL模式的可变集合，如Servlet规范中定义的那样，过滤器针对这些模式进行注册
*/
public Collection<String> getUrlPatterns() {
return this.urlPatterns;
}
/**
* 添加URL模式，如Servlet规范中所定义的，过滤器将针对这些模式进行注册
*/
public void addUrlPatterns(String... urlPatterns) {
Assert.notNull(urlPatterns, "UrlPatterns must not be null");
Collections.addAll(this.urlPatterns, urlPatterns);
}
/**
*
* @param first the first dispatcher type
* @param rest additional dispatcher types
*/
public void setDispatcherTypes(DispatcherType first, DispatcherType... rest) {
this.dispatcherTypes = EnumSet.of(first, rest);
}
/**
* Sets the dispatcher types that should be used with the registration. If not
* specified the types will be deduced based on the value of
* {@link #isAsyncSupported()}.
* @param dispatcherTypes the dispatcher types
*/
public void setDispatcherTypes(EnumSet<DispatcherType> dispatcherTypes) {
this.dispatcherTypes = dispatcherTypes;
}
/**
* Set if the filter mappings should be matched after any declared filter mappings of
* the ServletContext. Defaults to {@code false} indicating the filters are supposed
* to be matched before any declared filter mappings of the ServletContext.
* @param matchAfter if filter mappings are matched after
*/
public void setMatchAfter(boolean matchAfter) {
this.matchAfter = matchAfter;
}
/**
* Return if filter mappings should be matched after any declared Filter mappings of
* the ServletContext.
* @return if filter mappings are matched after
*/
public boolean isMatchAfter() {
return this.matchAfter;
}
@Override
protected String getDescription() {
Filter filter = getFilter();
Assert.notNull(filter, "Filter must not be null");
return "filter " + getOrDeduceName(filter);
}
//注册过滤器
@Override
protected Dynamic addRegistration(String description, ServletContext servletContext) {
Filter filter = getFilter();
return servletContext.addFilter(getOrDeduceName(filter), filter);
}
/**
* 配置过滤器的配置
*/
@Override
protected void configure(FilterRegistration.Dynamic registration) {
super.configure(registration);
EnumSet<DispatcherType> dispatcherTypes = this.dispatcherTypes;
if (dispatcherTypes == null) {
T filter = getFilter();
if (ClassUtils.isPresent("org.springframework.web.filter.OncePerRequestFilter",
filter.getClass().getClassLoader()) && filter instanceof OncePerRequestFilter) {
dispatcherTypes = EnumSet.allOf(DispatcherType.class);
}
else {
dispatcherTypes = EnumSet.of(DispatcherType.REQUEST);
}
}
Set<String> servletNames = new LinkedHashSet<>();
for (ServletRegistrationBean<?> servletRegistrationBean : this.servletRegistrationBeans) {
servletNames.add(servletRegistrationBean.getServletName());
}
servletNames.addAll(this.servletNames);
if (servletNames.isEmpty() && this.urlPatterns.isEmpty()) {
registration.addMappingForUrlPatterns(dispatcherTypes, this.matchAfter, DEFAULT_URL_MAPPINGS);
}
else {
if (!servletNames.isEmpty()) {
registration.addMappingForServletNames(dispatcherTypes, this.matchAfter,
StringUtils.toStringArray(servletNames));
}
if (!this.urlPatterns.isEmpty()) {
registration.addMappingForUrlPatterns(dispatcherTypes, this.matchAfter,
StringUtils.toStringArray(this.urlPatterns));
}
}
}
/**
* Return the {@link Filter} to be registered.
* @return the filter
*/
public abstract T getFilter();
@Override
public String toString() {
StringBuilder builder = new StringBuilder(getOrDeduceName(this));
if (this.servletNames.isEmpty() && this.urlPatterns.isEmpty()) {
builder.append(" urls=").append(Arrays.toString(DEFAULT_URL_MAPPINGS));
}
else {
if (!this.servletNames.isEmpty()) {
builder.append(" servlets=").append(this.servletNames);
}
if (!this.urlPatterns.isEmpty()) {
builder.append(" urls=").append(this.urlPatterns);
}
}
builder.append(" order=").append(getOrder());
return builder.toString();
}
}
public class FilterRegistrationBean<T extends Filter> extends AbstractFilterRegistrationBean<T> {
//将要注册的Filter对象
private T filter;
/**
* 创建一个FilterRegistrationBean实例对象
*/
public FilterRegistrationBean() {
}
/**
* 创建一个新的FilterRegistrationBean实例，使用指定的Filter和ServletRegistrationBean作为参数
* @param filter the filter to register
* @param servletRegistrationBeans associate {@link ServletRegistrationBean}s
*/
public FilterRegistrationBean(T filter, ServletRegistrationBean<?>... servletRegistrationBeans) {
super(servletRegistrationBeans);
Assert.notNull(filter, "Filter must not be null");
this.filter = filter;
}
//获取将要注册的获取器
@Override
public T getFilter() {
return this.filter;
}
/**
* 设置将要被注册的过滤器
*/
public void setFilter(T filter) {
Assert.notNull(filter, "Filter must not be null");
this.filter = filter;
}
}
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