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XWork is an command-pattern framework that is used to power WebWork
as well as other applications. XWork provides an Inversion of Control
container, a powerful expression language, data type conversion,
validation, and pluggable configuration.
/*
* Copyright (c) 2002-2006 by OpenSymphony
* All rights reserved.
*/
package com.opensymphony.xwork2.interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.config.entities.ExceptionMappingConfig;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.util.Iterator;
import java.util.List;
/**
*
*
* This interceptor forms the core functionality of the exception handling feature. Exception handling allows you to map
* an exception to a result code, just as if the action returned a result code instead of throwing an unexpected
* exception. When an exception is encountered, it is wrapped with an {@link ExceptionHolder} and pushed on the stack,
* providing easy access to the exception from within your result.
*
* Note: While you can configure exception mapping in your configuration file at any point, the configuration
* will not have any effect if this interceptor is not in the interceptor stack for your actions. It is recommended that
* you make this interceptor the first interceptor on the stack, ensuring that it has full access to catch any
* exception, even those caused by other interceptors.
*
*
*
* Interceptor parameters:
*
*
*
*
*
* - logEnabled (optional) - Should exceptions also be logged? (boolean true|false)
*
* - logLevel (optional) - what log level should we use (
trace, debug, info, warn, error, fatal)? - defaut is debug
*
* - logCategory (optional) - If provided we would use this category (eg.
com.mycompany.app).
* Default is to use com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.
*
*
*
* The parameters above enables us to log all thrown exceptions with stacktace in our own logfile,
* and present a friendly webpage (with no stacktrace) to the end user.
*
*
*
* Extending the interceptor:
*
*
*
*
*
* If you want to add custom handling for publishing the Exception, you may override
* {@link #publishException(com.opensymphony.xwork2.ActionInvocation, ExceptionHolder)}. The default implementation
* pushes the given ExceptionHolder on value stack. A custom implementation could add additional logging etc.
*
*
*
* Example code:
*
*
*
* <xwork>
* <package name="default" extends="xwork-default">
* <global-results>
* <result name="success" type="freemarker">error.ftl</result>
* </global-results>
*
* <global-exception-mappings>
* <exception-mapping exception="java.lang.Exception" result="error"/>
* </global-exception-mappings>
*
* <action name="test">
* <interceptor-ref name="exception"/>
* <interceptor-ref name="basicStack"/>
* <exception-mapping exception="com.acme.CustomException" result="custom_error"/>
* <result name="custom_error">custom_error.ftl</result>
* <result name="success" type="freemarker">test.ftl</result>
* </action>
* </package>
* </xwork>
*
*
*
*
* This second example will also log the exceptions using our own category
* com.mycompany.app.unhandled at WARN level.
*
*
*
* <xwork>
* <package name="something" extends="xwork-default">
* <interceptors>
* <interceptor-stack name="exceptionmapping-stack">
* <interceptor-ref name="exception">
* <param name="logEnabled">true</param>
* <param name="logCategory">com.mycompany.app.unhandled</param>
* <param name="logLevel">WARN</param>
* </interceptor-ref>
* <interceptor-ref name="i18n"/>
* <interceptor-ref name="static-params"/>
* <interceptor-ref name="params"/>
* <interceptor-ref name="validation">
* <param name="excludeMethods">input,back,cancel,browse</param>
* </interceptor-ref>
* </interceptor-stack>
* </interceptors>
*
* <default-interceptor-ref name="exceptionmapping-stack"/>
*
* <global-results>
* <result name="unhandledException">/unhandled-exception.jsp</result>
* </global-results>
*
* <global-exception-mappings>
* <exception-mapping exception="java.lang.Exception" result="unhandledException"/>
* </global-exception-mappings>
*
* <action name="exceptionDemo" class="org.apache.struts2.showcase.exceptionmapping.ExceptionMappingAction">
* <exception-mapping exception="org.apache.struts2.showcase.exceptionmapping.ExceptionMappingException"
* result="damm"/>
* <result name="input">index.jsp</result>
* <result name="success">success.jsp</result>
* <result name="damm">damm.jsp</result>
* </action>
*
* </package>
* </xwork>
*
*
*
* @author Matthew E. Porter (matthew dot porter at metissian dot com)
* @author Claus Ibsen
*/
public class ExceptionMappingInterceptor extends AbstractInterceptor {
protected static final Log log = LogFactory.getLog(ExceptionMappingInterceptor.class);
protected Log categoryLogger;
protected boolean logEnabled = false;
protected String logCategory;
protected String logLevel;
public boolean isLogEnabled() {
return logEnabled;
}
public void setLogEnabled(boolean logEnabled) {
this.logEnabled = logEnabled;
}
public String getLogCategory() {
return logCategory;
}
public void setLogCategory(String logCatgory) {
this.logCategory = logCatgory;
}
public String getLogLevel() {
return logLevel;
}
public void setLogLevel(String logLevel) {
this.logLevel = logLevel;
}
public String intercept(ActionInvocation invocation) throws Exception {
String result;
try {
result = invocation.invoke();
} catch (Exception e) {
if (logEnabled) {
handleLogging(e);
}
List exceptionMappings = invocation.getProxy().getConfig().getExceptionMappings();
String mappedResult = this.findResultFromExceptions(exceptionMappings, e);
if (mappedResult != null) {
result = mappedResult;
publishException(invocation, new ExceptionHolder(e));
} else {
throw e;
}
}
return result;
}
/**
* Handles the logging of the exception.
*
* @param e the exception to log.
*/
protected void handleLogging(Exception e) {
if (logCategory != null) {
if (categoryLogger == null) {
// init category logger
categoryLogger = LogFactory.getLog(logCategory);
}
doLog(categoryLogger, e);
} else {
doLog(log, e);
}
}
/**
* Performs the actual logging.
*
* @param logger the provided logger to use.
* @param e the exception to log.
*/
protected void doLog(Log logger, Exception e) {
if (logLevel == null) {
logger.debug(e.getMessage(), e);
return;
}
if ("trace".equalsIgnoreCase(logLevel)) {
logger.trace(e.getMessage(), e);
} else if ("debug".equalsIgnoreCase(logLevel)) {
logger.debug(e.getMessage(), e);
} else if ("info".equalsIgnoreCase(logLevel)) {
logger.info(e.getMessage(), e);
} else if ("warn".equalsIgnoreCase(logLevel)) {
logger.warn(e.getMessage(), e);
} else if ("error".equalsIgnoreCase(logLevel)) {
logger.error(e.getMessage(), e);
} else if ("fatal".equalsIgnoreCase(logLevel)) {
logger.fatal(e.getMessage(), e);
} else {
throw new IllegalArgumentException("LogLevel [" + logLevel + "] is not supported");
}
}
private String findResultFromExceptions(List exceptionMappings, Throwable t) {
String result = null;
// Check for specific exception mappings.
if (exceptionMappings != null) {
int deepest = Integer.MAX_VALUE;
for (Iterator iter = exceptionMappings.iterator(); iter.hasNext();) {
ExceptionMappingConfig exceptionMappingConfig = (ExceptionMappingConfig) iter.next();
int depth = getDepth(exceptionMappingConfig.getExceptionClassName(), t);
if (depth >= 0 && depth < deepest) {
deepest = depth;
result = exceptionMappingConfig.getResult();
}
}
}
return result;
}
/**
* Return the depth to the superclass matching. 0 means ex matches exactly. Returns -1 if there's no match.
* Otherwise, returns depth. Lowest depth wins.
*
* @param exceptionMapping the mapping classname
* @param t the cause
* @return the depth, if not found -1 is returned.
*/
public int getDepth(String exceptionMapping, Throwable t) {
return getDepth(exceptionMapping, t.getClass(), 0);
}
private int getDepth(String exceptionMapping, Class exceptionClass, int depth) {
if (exceptionClass.getName().indexOf(exceptionMapping) != -1) {
// Found it!
return depth;
}
// If we've gone as far as we can go and haven't found it...
if (exceptionClass.equals(Throwable.class)) {
return -1;
}
return getDepth(exceptionMapping, exceptionClass.getSuperclass(), depth + 1);
}
/**
* Default implementation to handle ExceptionHolder publishing. Pushes given ExceptionHolder on the stack.
* Subclasses may override this to customize publishing.
*
* @param invocation The invocation to publish Exception for.
* @param exceptionHolder The exceptionHolder wrapping the Exception to publish.
*/
protected void publishException(ActionInvocation invocation, ExceptionHolder exceptionHolder) {
invocation.getStack().push(exceptionHolder);
}
}