/*
* Copyright (c) 2002-2012 Alibaba Group Holding Limited.
* All rights reserved.
*
* 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
*
* http://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 com.alibaba.citrus.webx.servlet;
import static com.alibaba.citrus.util.Assert.*;
import static com.alibaba.citrus.util.CollectionUtil.*;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Set;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
import com.alibaba.citrus.util.internal.Servlet3Util.Servlet3OutputStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeansException;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.PropertyAccessorFactory;
import org.springframework.beans.PropertyValue;
import org.springframework.beans.PropertyValues;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceEditor;
import org.springframework.core.io.ResourceLoader;
import org.springframework.web.context.support.ServletContextResourceLoader;
import org.springframework.web.servlet.HttpServletBean;
/**
* 支持注入参数的filter基类。
* <p>
* 将init-params注入到filter中，将request和response转换成 <code>HttpServletRequest</code>和
* <code>HttpServletResponse</code>。
* </p>
*
* @author Michael Zhou
* @see HttpServletBean
*/
public abstract class FilterBean implements Filter {
protected final Logger log = LoggerFactory.getLogger(getClass());
private final Set<String> requiredProperties = createHashSet();
private FilterConfig filterConfig;
/** 添加一个必选配置项。 */
protected final void addRequiredProperty(String name) {
this.requiredProperties.add(name);
}
/** 初始化filter。 */
public final void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
logInBothServletAndLoggingSystem("Initializing filter: " + getFilterName());
try {
PropertyValues pvs = new FilterConfigPropertyValues(getFilterConfig(), requiredProperties);
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
ResourceLoader resourceLoader = new ServletContextResourceLoader(getServletContext());
bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader));
initBeanWrapper(bw);
bw.setPropertyValues(pvs, true);
} catch (Exception e) {
throw new ServletException("Failed to set bean properties on filter: " + getFilterName(), e);
}
try {
init();
} catch (Exception e) {
throw new ServletException("Failed to init filter: " + getFilterName(), e);
}
logInBothServletAndLoggingSystem(getClass().getSimpleName() + " - " + getFilterName()
+ ": initialization completed");
}
protected final void logInBothServletAndLoggingSystem(String msg) {
getServletContext().log(msg);
log.info(msg);
}
/** 初始化<code>BeanWrapper</code>。 */
protected void initBeanWrapper(BeanWrapper bw) throws BeansException {
}
/** 初始化Filter。 */
protected void init() throws Exception {
}
/** 清理filter。 */
public void destroy() {
}
/** 取得filter的配置。 */
public final FilterConfig getFilterConfig() {
return filterConfig;
}
/** 取得定义在web.xml中的filter名字。 */
public final String getFilterName() {
return filterConfig == null ? null : filterConfig.getFilterName();
}
/** 取得当前webapp的context。 */
public final ServletContext getServletContext() {
return filterConfig == null ? null : filterConfig.getServletContext();
}
public final void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
ServletException {
if (request instanceof HttpServletRequest && response instanceof HttpServletResponse) {
HttpServletRequest httpRequest = (HttpServletRequest) request;
HttpServletResponse httpResponse = (HttpServletResponse) response;
String method = httpRequest.getMethod();
if ("HEAD".equalsIgnoreCase(method)) {
httpResponse = new NoBodyResponse(httpResponse);
}
try {
doFilter(httpRequest, httpResponse, chain);
} finally {
if (httpResponse instanceof NoBodyResponse) {
((NoBodyResponse) httpResponse).setContentLength();
}
}
} else {
log.debug("Skipped filtering due to the unknown request/response types: {}, {}", request.getClass()
.getName(), response.getClass().getName());
chain.doFilter(request, response);
}
}
protected abstract void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
throws IOException, ServletException;
/** 从filter config中取得所有的init-params。 */
private static class FilterConfigPropertyValues extends MutablePropertyValues {
private static final long serialVersionUID = -5359131251714023794L;
public FilterConfigPropertyValues(FilterConfig config, Set<String> requiredProperties) throws ServletException {
Set<String> missingProps = createTreeSet(requiredProperties);
for (Enumeration<?> e = config.getInitParameterNames(); e.hasMoreElements(); ) {
String key = (String) e.nextElement();
String value = config.getInitParameter(key);
addPropertyValue(new PropertyValue(key, value));
missingProps.remove(key);
}
assertTrue(missingProps.isEmpty(), "Initialization for filter %s failed. "
+ "The following required properties were missing: %s", config.getFilterName(), missingProps);
}
}
/** 不返回response body的response实现。 */
private static class NoBodyResponse extends HttpServletResponseWrapper {
private NoBodyOutputStream noBody = new NoBodyOutputStream();
private PrintWriter writer;
private boolean didSetContentLength;
public NoBodyResponse(HttpServletResponse response) {
super(response);
}
public void setContentLength() {
if (!didSetContentLength) {
super.setContentLength(noBody.getContentLength());
}
}
@Override
public void setContentLength(int len) {
super.setContentLength(len);
didSetContentLength = true;
}
@Override
public ServletOutputStream getOutputStream() throws IOException {
return noBody;
}
@Override
public PrintWriter getWriter() throws UnsupportedEncodingException {
if (writer == null) {
writer = new PrintWriter(new OutputStreamWriter(noBody, getCharacterEncoding()));
}
return writer;
}
}
/** 不返回response body的servlet output stream实现。 */
private static class NoBodyOutputStream extends Servlet3OutputStream {
private int contentLength;
public NoBodyOutputStream() {
super(null);
contentLength = 0;
}
public int getContentLength() {
return contentLength;
}
@Override
public void write(int b) {
contentLength++;
}
@Override
public void write(byte[] buf, int offset, int len) throws IOException {
if (len >= 0) {
contentLength += len;
} else {
throw new IOException("negative length");
}
}
}
}