/*
* Copyright 2002-2008 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
*
* 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 org.springframework.aop.interceptor;
import java.io.Serializable;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.aop.support.AopUtils;
/**
* Base <code>MethodInterceptor</code> implementation for tracing.
*
* <p>By default, log messages are written to the log for the interceptor class,
* not the class which is being intercepted. Setting the <code>useDynamicLogger</code>
* bean property to <code>true</code> causes all log messages to be written to
* the <code>Log</code> for the target class being intercepted.
*
* <p>Subclasses must implement the <code>invokeUnderTrace</code> method, which
* is invoked by this class ONLY when a particular invocation SHOULD be traced.
* Subclasses should write to the <code>Log</code> instance provided.
*
* @author Rob Harrop
* @author Juergen Hoeller
* @since 1.2
* @see #setUseDynamicLogger
* @see #invokeUnderTrace(org.aopalliance.intercept.MethodInvocation, org.apache.commons.logging.Log)
*/
public abstract class AbstractTraceInterceptor implements MethodInterceptor, Serializable {
/**
* The default <code>Log</code> instance used to write trace messages.
* This instance is mapped to the implementing <code>Class</code>.
*/
protected transient Log defaultLogger = LogFactory.getLog(getClass());
/**
* Indicates whether or not proxy class names should be hidden when using dynamic loggers.
* @see #setUseDynamicLogger
*/
private boolean hideProxyClassNames = false;
/**
* Set whether to use a dynamic logger or a static logger.
* Default is a static logger for this trace interceptor.
* <p>Used to determine which <code>Log</code> instance should be used to write
* log messages for a particular method invocation: a dynamic one for the
* <code>Class</code> getting called, or a static one for the <code>Class</code>
* of the trace interceptor.
* <p><b>NOTE:</b> Specify either this property or "loggerName", not both.
* @see #getLoggerForInvocation(org.aopalliance.intercept.MethodInvocation)
*/
public void setUseDynamicLogger(boolean useDynamicLogger) {
// Release default logger if it is not being used.
this.defaultLogger = (useDynamicLogger ? null : LogFactory.getLog(getClass()));
}
/**
* Set the name of the logger to use. The name will be passed to the
* underlying logger implementation through Commons Logging, getting
* interpreted as log category according to the logger's configuration.
* <p>This can be specified to not log into the category of a class
* (whether this interceptor's class or the class getting called)
* but rather into a specific named category.
* <p><b>NOTE:</b> Specify either this property or "useDynamicLogger", not both.
* @see org.apache.commons.logging.LogFactory#getLog(String)
* @see org.apache.log4j.Logger#getLogger(String)
* @see java.util.logging.Logger#getLogger(String)
*/
public void setLoggerName(String loggerName) {
this.defaultLogger = LogFactory.getLog(loggerName);
}
/**
* Set to "true" to have {@link #setUseDynamicLogger dynamic loggers} hide
* proxy class names wherever possible. Default is "false".
*/
public void setHideProxyClassNames(boolean hideProxyClassNames) {
this.hideProxyClassNames = hideProxyClassNames;
}
/**
* Determines whether or not logging is enabled for the particular <code>MethodInvocation</code>.
* If not, the method invocation proceeds as normal, otherwise the method invocation is passed
* to the <code>invokeUnderTrace</code> method for handling.
* @see #invokeUnderTrace(org.aopalliance.intercept.MethodInvocation, org.apache.commons.logging.Log)
*/
public Object invoke(MethodInvocation invocation) throws Throwable {
Log logger = getLoggerForInvocation(invocation);
if (isInterceptorEnabled(invocation, logger)) {
return invokeUnderTrace(invocation, logger);
}
else {
return invocation.proceed();
}
}
/**
* Return the appropriate <code>Log</code> instance to use for the given
* <code>MethodInvocation</code>. If the <code>useDynamicLogger</code> flag
* is set, the <code>Log</code> instance will be for the target class of the
* <code>MethodInvocation</code>, otherwise the <code>Log</code> will be the
* default static logger.
* @param invocation the <code>MethodInvocation</code> being traced
* @return the <code>Log</code> instance to use
* @see #setUseDynamicLogger
*/
protected Log getLoggerForInvocation(MethodInvocation invocation) {
if (this.defaultLogger != null) {
return this.defaultLogger;
}
else {
Object target = invocation.getThis();
return LogFactory.getLog(getClassForLogging(target));
}
}
/**
* Determine the class to use for logging purposes.
* @param target the target object to introspect
* @return the target class for the given object
* @see #setHideProxyClassNames
*/
protected Class getClassForLogging(Object target) {
return (this.hideProxyClassNames ? AopUtils.getTargetClass(target) : target.getClass());
}
/**
* Determine whether the interceptor should kick in, that is,
* whether the <code>invokeUnderTrace</code> method should be called.
* <p>Default behavior is to check whether the given <code>Log</code>
* instance is enabled. Subclasses can override this to apply the
* interceptor in other cases as well.
* @param invocation the <code>MethodInvocation</code> being traced
* @param logger the <code>Log</code> instance to check
* @see #invokeUnderTrace
* @see #isLogEnabled
*/
protected boolean isInterceptorEnabled(MethodInvocation invocation, Log logger) {
return isLogEnabled(logger);
}
/**
* Determine whether the given {@link Log} instance is enabled.
* <p>Default is <code>true</code> when the "trace" level is enabled.
* Subclasses can override this to change the level under which 'tracing' occurs.
* @param logger the <code>Log</code> instance to check
*/
protected boolean isLogEnabled(Log logger) {
return logger.isTraceEnabled();
}
/**
* Subclasses must override this method to perform any tracing around the
* supplied <code>MethodInvocation</code>. Subclasses are responsible for
* ensuring that the <code>MethodInvocation</code> actually executes by
* calling <code>MethodInvocation.proceed()</code>.
* <p>By default, the passed-in <code>Log</code> instance will have log level
* "trace" enabled. Subclasses do not have to check for this again, unless
* they overwrite the <code>isInterceptorEnabled</code> method to modify
* the default behavior.
* @param logger the <code>Log</code> to write trace messages to
* @return the result of the call to <code>MethodInvocation.proceed()</code>
* @throws Throwable if the call to <code>MethodInvocation.proceed()</code>
* encountered any errors
* @see #isInterceptorEnabled
* @see #isLogEnabled
*/
protected abstract Object invokeUnderTrace(MethodInvocation invocation, Log logger) throws Throwable;
}