com.opensymphony.xwork2.interceptor
public class: ExceptionMappingInterceptor [javadoc |
source]
java.lang.Object
com.opensymphony.xwork2.interceptor.AbstractInterceptor
com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor
All Implemented Interfaces:
Interceptor
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
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
#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="error" 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="exceptionmappingStack">
<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="staticParams"/>
<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="exceptionmappingStack"/>
<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
| Field Summary |
|---|
| protected static final Logger | LOG | |
| protected Logger | categoryLogger | |
| protected boolean | logEnabled | |
| protected String | logCategory | |
| protected String | logLevel | |
| Method from com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor Summary: |
|---|
|
doLog, findResultFromExceptions, getDepth, getLogCategory, getLogLevel, handleLogging, intercept, isLogEnabled, publishException, setLogCategory, setLogEnabled, setLogLevel |
| Methods from java.lang.Object: |
|---|
|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Method from com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor Detail: |
|---|
 protected void doLog(Logger 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");
}
}
Performs the actual logging. |
protected String findResultFromExceptions(List<ExceptionMappingConfig> exceptionMappings,
Throwable t) {
String result = null;
// Check for specific exception mappings.
if (exceptionMappings != null) {
int deepest = Integer.MAX_VALUE;
for (Object exceptionMapping : exceptionMappings) {
ExceptionMappingConfig exceptionMappingConfig = (ExceptionMappingConfig) exceptionMapping;
int depth = getDepth(exceptionMappingConfig.getExceptionClassName(), t);
if (depth >= 0 && depth < deepest) {
deepest = depth;
result = exceptionMappingConfig.getResult();
}
}
}
return result;
} |
public int getDepth(String exceptionMapping,
Throwable t) {
return getDepth(exceptionMapping, t.getClass(), 0);
} 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. |
public String getLogCategory() {
return logCategory;
} |
public String getLogLevel() {
return logLevel;
} |
protected void handleLogging(Exception e) {
if (logCategory != null) {
if (categoryLogger == null) {
// init category logger
categoryLogger = LoggerFactory.getLogger(logCategory);
}
doLog(categoryLogger, e);
} else {
doLog(LOG, e);
}
} Handles the logging of the exception. |
public String intercept(ActionInvocation invocation) throws Exception {
String result;
try {
result = invocation.invoke();
} catch (Exception e) {
if (isLogEnabled()) {
handleLogging(e);
}
List< ExceptionMappingConfig > 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;
} |
public boolean isLogEnabled() {
return logEnabled;
} |
protected void publishException(ActionInvocation invocation,
ExceptionHolder exceptionHolder) {
invocation.getStack().push(exceptionHolder);
} Default implementation to handle ExceptionHolder publishing. Pushes given ExceptionHolder on the stack.
Subclasses may override this to customize publishing. |
public void setLogCategory(String logCatgory) {
this.logCategory = logCatgory;
} |
public void setLogEnabled(boolean logEnabled) {
this.logEnabled = logEnabled;
} |
public void setLogLevel(String logLevel) {
this.logLevel = logLevel;
} |