/*
* 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.util.internal;
import static com.alibaba.citrus.util.Assert.*;
import static com.alibaba.citrus.util.CollectionUtil.*;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.EventListener;
import java.util.List;
import javax.servlet.ServletOutputStream;
import javax.servlet.WriteListener;
import javax.servlet.http.HttpServletRequest;
import net.sf.cglib.reflect.FastClass;
import net.sf.cglib.reflect.FastMethod;
/**
* Servlet 3.0 Support － 即使在非servlet 3.0的环境中，也不会出错。
* 此类会引用如下几个Servlet 3.0的接口。在Servlet 2.5的环境中，接口由<code>citrus-common-servlet</code>项目提供。
* <ul>
* <li><code>WriteListener</code></li>
* </ul>
*
* @author Michael Zhou
*/
public class Servlet3Util {
public static final Enum<?> DISPATCHER_TYPE_FORWARD = getEnum("javax.servlet.DispatcherType", "FORWARD");
public static final Enum<?> DISPATCHER_TYPE_INCLUDE = getEnum("javax.servlet.DispatcherType", "INCLUDE");
public static final Enum<?> DISPATCHER_TYPE_REQUEST = getEnum("javax.servlet.DispatcherType", "REQUEST");
public static final Enum<?> DISPATCHER_TYPE_ASYNC = getEnum("javax.servlet.DispatcherType", "ASYNC");
public static final Enum<?> DISPATCHER_TYPE_ERROR = getEnum("javax.servlet.DispatcherType", "ERROR");
public static final Class<?> asyncContextClass = loadClass("javax.servlet.AsyncContext");
public static final Class<?> asyncListenerClass = loadClass("javax.servlet.AsyncListener");
public static final Class<?> asyncEventClass = loadClass("javax.servlet.AsyncEvent");
public static final Class<?> writeListenerClass = loadClass("javax.servlet.WriteListener");
private static final InterfaceImplementorBuilder asyncListenerBuilder;
private static final MethodInfo[] methods;
private static final int request_isAsyncStarted;
private static final int request_getAsyncContext;
private static final int request_getDispatcherType;
private static final int asyncContext_addListener;
private static final int asyncEvent_getAsyncContext;
private static final int servletOutputStream_isReady;
private static final int servletOutputStream_setWriteListener;
private static boolean disableServlet3Features = false;
private static final boolean servlet3;
static {
List<MethodInfo> methodList = createLinkedList();
int count = 0;
methodList.add(new MethodInfo(Boolean.class, false, HttpServletRequest.class, "isAsyncStarted"));
request_isAsyncStarted = count++;
methodList.add(new MethodInfo(Object.class, null, HttpServletRequest.class, "getAsyncContext"));
request_getAsyncContext = count++;
methodList.add(new MethodInfo(Enum.class, null, HttpServletRequest.class, "getDispatcherType"));
request_getDispatcherType = count++;
methodList.add(new MethodInfo(null, null, asyncContextClass, "addListener", asyncListenerClass));
asyncContext_addListener = count++;
methodList.add(new MethodInfo(asyncContextClass, null, asyncEventClass, "getAsyncContext"));
asyncEvent_getAsyncContext = count++;
methodList.add(new MethodInfo(Boolean.class, true, ServletOutputStream.class, "isReady"));
servletOutputStream_isReady = count++;
// 这里不能硬编码WriteListener.class，否则在servlet 3.0环境中会失败。
if (writeListenerClass == null) {
methodList.add(new MethodInfo(null, null));
} else {
methodList.add(new MethodInfo(null, null, ServletOutputStream.class, "setWriteListener", writeListenerClass));
}
servletOutputStream_setWriteListener = count++;
methods = methodList.toArray(new MethodInfo[methodList.size()]);
servlet3 = !methods[request_getAsyncContext].isDisabled();
asyncListenerBuilder = asyncListenerClass == null
? null
: new InterfaceImplementorBuilder().addInterface(asyncListenerClass).setOverriderClass(MyAsyncListener.class).init();
}
public static boolean isServlet3() {
return servlet3;
}
/**
* 设置强制禁用servlet 3.0特性。
* 有一种情况：当用httpunit测试时，虽然存在servlet 3.0的API包，但是由于httpunit未实现servlet 3.0而报错。
* 在这种情况下，可强制禁用servlet 3.0，让测试通过。
*/
public static boolean setDisableServlet3Features(boolean disabled) {
boolean originalValue = disableServlet3Features;
disableServlet3Features = disabled;
return originalValue;
}
public static boolean request_isAsyncStarted(HttpServletRequest request) {
return (Boolean) invoke(request_isAsyncStarted, request);
}
public static Object /* AsyncContext */ request_getAsyncContext(HttpServletRequest request) {
int index = request_getAsyncContext;
if (methods[index].isDisabled()) {
throw new IllegalStateException("request.getAsyncContext");
}
return invoke(index, request);
}
public static boolean request_isDispatcherType(HttpServletRequest request, Enum<?> type) {
Enum<?> dispatcherType = (Enum<?>) invoke(request_getDispatcherType, request);
if (dispatcherType == null || type == null) {
return false; // unsupported
} else {
return dispatcherType == type;
}
}
public static Object /* AsyncContext */ asyncEvent_getAsyncContext(Object /* AsyncEvent */ event) {
return invoke(asyncEvent_getAsyncContext, event);
}
public static void asyncContext_addAsyncListener(Object /* AsyncContext */ asyncContext, Object /* AsyncListener */ listener) {
invoke(asyncContext_addListener, asyncContext, listener);
}
public static void request_registerAsyncListener(HttpServletRequest request, MyAsyncListener listenerImpl) {
Object /* AsyncContext */ asyncContext = request_getAsyncContext(request);
Object listener = assertNotNull(asyncListenerBuilder, "asyncListenerBuilder").toObject(listenerImpl); // builder should not be null
invoke(asyncContext_addListener, asyncContext, listener);
}
private static Class<?> loadClass(String className) {
try {
return Servlet3Util.class.getClassLoader().loadClass(className);
} catch (ClassNotFoundException e) {
return null;
}
}
private static Object invoke(int methodIndex, Object target, Object... args) {
MethodInfo method = methods[methodIndex];
if (method.isDisabled()) {
return method.defaultReturnValue;
}
try {
if (method.returnValueType == null) {
method.method.invoke(target, args);
return null;
} else {
return method.returnValueType.cast(method.method.invoke(target, args));
}
} catch (InvocationTargetException e) {
Throwable t = e.getTargetException();
if (t instanceof RuntimeException) {
throw (RuntimeException) t;
} else if (t instanceof Error) {
throw (Error) t;
} else {
throw new RuntimeException(t);
}
}
}
private static Enum<?> getEnum(String className, String name) {
Class<?> enumClass = null;
try {
enumClass = Servlet3Util.class.getClassLoader().loadClass(className);
} catch (ClassNotFoundException e) {
return null;
}
assertTrue(Enum.class.isAssignableFrom(enumClass), "%s is not a enum class", enumClass.getName());
try {
return (Enum<?>) enumClass.getField(name).get(null);
} catch (Exception e) {
unexpectedException(e);
return null;
}
}
private static class MethodInfo {
private final FastMethod method;
private final Object defaultReturnValue;
private final Class<?> returnValueType;
// 创建一个空的method
public <T> MethodInfo(Class<T> returnValueType, T defaultReturnValue) {
this(returnValueType, defaultReturnValue, null, null, (Class<?>[]) null);
}
public <T> MethodInfo(Class<T> returnValueType, T defaultReturnValue, Class<?> declaringClass, String methodName, Class<?>... parameterTypes) {
this.returnValueType = returnValueType;
this.defaultReturnValue = defaultReturnValue;
Method javaMethod;
FastMethod method = null;
if (declaringClass != null) {
try {
javaMethod = declaringClass.getMethod(methodName, parameterTypes);
method = FastClass.create(getClass().getClassLoader(), declaringClass).getMethod(javaMethod);
} catch (NoSuchMethodException e) {
}
}
this.method = method;
}
public boolean isDisabled() {
return disableServlet3Features || method == null;
}
}
public interface MyAsyncListener extends EventListener {
void onComplete(Object /* AsyncEvent */ event) throws IOException;
void onTimeout(Object /* AsyncEvent */ event) throws IOException;
void onError(Object /* AsyncEvent */ event) throws IOException;
void onStartAsync(Object /* AsyncEvent */ event) throws IOException;
}
/** 一个可同时在servlet 3.0和servlet 2.5环境下使用的基类。 */
public static abstract class Servlet3OutputStream extends ServletOutputStream {
protected final ServletOutputStream originalStream;
public Servlet3OutputStream(ServletOutputStream originalStream) {
this.originalStream = originalStream;
}
// @Override
public boolean isReady() {
if (originalStream != null) {
return (Boolean) invoke(servletOutputStream_isReady, originalStream);
}
return true;
}
// @Override
public void setWriteListener(WriteListener writeListener) {
if (originalStream != null) {
invoke(servletOutputStream_setWriteListener, originalStream, writeListener);
}
}
}
}