org.springframework.web.servlet.handler.SimpleServletPostProcessor Maven / Gradle / Ivy
/*
* Copyright 2002-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.servlet.handler;
import java.util.Collections;
import java.util.Enumeration;
import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanInitializationException;
import org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor;
import org.springframework.lang.Nullable;
import org.springframework.web.context.ServletConfigAware;
import org.springframework.web.context.ServletContextAware;
/**
* {@link org.springframework.beans.factory.config.BeanPostProcessor}
* that applies initialization and destruction callbacks to beans that
* implement the {@link javax.servlet.Servlet} interface.
*
* After initialization of the bean instance, the Servlet {@code init}
* method will be called with a ServletConfig that contains the bean name
* of the Servlet and the ServletContext that it is running in.
*
*
Before destruction of the bean instance, the Servlet {@code destroy}
* will be called.
*
*
Note that this post-processor does not support Servlet initialization
* parameters. Bean instances that implement the Servlet interface are
* supposed to be configured like any other Spring bean, that is, through
* constructor arguments or bean properties.
*
*
For reuse of a Servlet implementation in a plain Servlet container
* and as a bean in a Spring context, consider deriving from Spring's
* {@link org.springframework.web.servlet.HttpServletBean} base class that
* applies Servlet initialization parameters as bean properties, supporting
* both the standard Servlet and the Spring bean initialization style.
*
*
Alternatively, consider wrapping a Servlet with Spring's
* {@link org.springframework.web.servlet.mvc.ServletWrappingController}.
* This is particularly appropriate for existing Servlet classes,
* allowing to specify Servlet initialization parameters etc.
*
* @author Juergen Hoeller
* @since 1.1.5
* @see javax.servlet.Servlet#init(javax.servlet.ServletConfig)
* @see javax.servlet.Servlet#destroy()
* @see SimpleServletHandlerAdapter
*/
public class SimpleServletPostProcessor implements
DestructionAwareBeanPostProcessor, ServletContextAware, ServletConfigAware {
private boolean useSharedServletConfig = true;
@Nullable
private ServletContext servletContext;
@Nullable
private ServletConfig servletConfig;
/**
* Set whether to use the shared ServletConfig object passed in
* through {@code setServletConfig}, if available.
*
Default is "true". Turn this setting to "false" to pass in
* a mock ServletConfig object with the bean name as servlet name,
* holding the current ServletContext.
* @see #setServletConfig
*/
public void setUseSharedServletConfig(boolean useSharedServletConfig) {
this.useSharedServletConfig = useSharedServletConfig;
}
@Override
public void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
}
@Override
public void setServletConfig(ServletConfig servletConfig) {
this.servletConfig = servletConfig;
}
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if (bean instanceof Servlet) {
ServletConfig config = this.servletConfig;
if (config == null || !this.useSharedServletConfig) {
config = new DelegatingServletConfig(beanName, this.servletContext);
}
try {
((Servlet) bean).init(config);
}
catch (ServletException ex) {
throw new BeanInitializationException("Servlet.init threw exception", ex);
}
}
return bean;
}
@Override
public void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException {
if (bean instanceof Servlet) {
((Servlet) bean).destroy();
}
}
@Override
public boolean requiresDestruction(Object bean) {
return (bean instanceof Servlet);
}
/**
* Internal implementation of the {@link ServletConfig} interface,
* to be passed to the wrapped servlet.
*/
private static class DelegatingServletConfig implements ServletConfig {
private final String servletName;
@Nullable
private final ServletContext servletContext;
public DelegatingServletConfig(String servletName, @Nullable ServletContext servletContext) {
this.servletName = servletName;
this.servletContext = servletContext;
}
@Override
public String getServletName() {
return this.servletName;
}
@Override
@Nullable
public ServletContext getServletContext() {
return this.servletContext;
}
@Override
@Nullable
public String getInitParameter(String paramName) {
return null;
}
@Override
public Enumeration getInitParameterNames() {
return Collections.enumeration(Collections.emptySet());
}
}
}