/*
* $Header: /home/cvs/jakarta-struts/contrib/scaffold/src/java/org/apache/struts/scaffold/BizAction.java,v 1.5 2004/03/14 14:32:19 husted Exp $
* $Revision: 1.5 $
* $Date: 2004/03/14 14:32:19 $
*
* Copyright 2001-2004 The Apache Software Foundation.
*
* 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.apache.struts.scaffold;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Iterator;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.beanutils.BeanUtils;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.commons.scaffold.lang.Log;
import org.apache.commons.scaffold.lang.ParameterException;
import org.apache.commons.scaffold.lang.Tokens;
import org.apache.commons.scaffold.util.BizRequest;
import org.apache.commons.scaffold.util.BizResponse;
import org.apache.commons.scaffold.util.BizService;
import org.apache.commons.scaffold.util.Message;
import org.apache.commons.scaffold.util.ResultList;
import org.apache.commons.scaffold.util.ResultListBase;
/**
* Advanced framework class to invoke a business service
* and process the response.
*
* @version $Revision: 1.5 $ $Date: 2004/03/14 14:32:19 $
*/
public class BizAction extends BaseHelperAction {
/**
* Exposes result in a servlet context.
* If there is an existing bean with same attribute name in the target
* context,
* then the matching properties on that bean are populated with the
* result.
*
* @param request the request being serviced
* @param name The name to use in scope
* @param scope The scope to set the attribute in
* @param bean The attribute to be set
*/
protected void exposeInScope(
HttpServletRequest request,
String name,
String scope,
Object bean) {
if ((null==scope) || (null==bean)) {
servlet.log(Log.PROCESS_BEAN_NULL_SCOPE,Log.DEBUG);
return;
}
if (Tokens.REQUEST.equals(scope)) {
Object form = request.getAttribute(name);
if (null==form) {
request.setAttribute(name,bean);
}
else {
try {
BeanUtils.copyProperties(form,bean);
}
catch (Exception e) {
throw new RuntimeException(e.toString());
}
}
}
else if (Tokens.SESSION.equals(scope)) {
Object form = request.getSession().getAttribute(name);
if (null==form) {
request.getSession().setAttribute(name,bean);
}
else {
try {
BeanUtils.copyProperties(form,bean);
}
catch (Exception e) {
throw new RuntimeException(e.toString());
}
}
}
else if (Tokens.APPLICATION.equals(scope)) {
Object form = servlet.getServletContext().getAttribute(name);
if (null==form) {
servlet.getServletContext().setAttribute(name,bean);
}
else {
try {
BeanUtils.copyProperties(form,bean);
}
catch (Exception e) {
throw new RuntimeException(e.toString());
}
}
}
else {
StringBuffer sb = new StringBuffer("exposeInScope: ");
sb.append(scope);
sb.append(Tokens.INVALID_SCOPE);
servlet.log(sb.toString(),Log.DEBUG);
throw new IllegalArgumentException(sb.toString());
}
} // end exposeInScope()
/**
* Save the result object within the business response to servlet context.
* <p>
* <code>bizResponse.getData()</code> must return non-null.
* <p>
* If <code>bizResponse.getName()</code> is null, the mapping's attribute
* (<code>mapping.getAttribute()</code>) is used instead.
* By default, this is the <code>form-bean</code>'s name.
* <p>
* If data is a Collection, only the first element is stored.
*
* @param mapping The ActionMapping used to select this instance
* @param request The HTTP request we are processing
* @param bizResponse The BizResponse we are handling
*/
protected void checkDataSingle(
ActionMapping mapping,
HttpServletRequest request,
BizResponse bizResponse) {
String name = bizResponse.getName();
if (null==name) {
// use form-bean or mapping name
name = mapping.getAttribute();
bizResponse.setName(name);
}
String scope = bizResponse.getScope();
Object bean = bizResponse.getData();
// if data is collection, use first element
if (bean instanceof Collection) {
Collection collection = (Collection) bean;
if (collection.isEmpty()) {
// for lack of a better idea, get a fresh form-bean
// this will return null if there is not a form-bean
// associated with this mapping
bean = createHelperBean(request,mapping.getName());
}
else {
bean = collection.iterator().next();
}
}
if (bizResponse.isExposed()) {
exposeInScope(request,name,scope,bean);
}
} // end checkDataSingle
/**
* Save any result objects within the business response to servlet context.
* <p>
* <code>bizResponse.getData()</code> must return non-null.
* <p>
* If <code>bizResponse.getName()</code> is null, the mapping's attribute
* (<code>mapping.getAttribute()</code>) is used instead.
* By default, this is the <code>form-bean</code>'s name.
*
* @param mapping The ActionMapping used to select this instance
* @param request The HTTP request we are processing
* @param bizResponse The BizResponse we are handling
*/
protected void checkData(
ActionMapping mapping,
HttpServletRequest request,
BizResponse bizResponse) {
if (bizResponse.isSingleForm()) {
checkDataSingle(mapping,request,bizResponse);
}
else {
String name = bizResponse.getName();
if (null==name) {
name = Tokens.LIST_KEY;
bizResponse.setName(name);
}
String scope = bizResponse.getScope();
Object bean = bizResponse.getData();
if (bizResponse.isExposed()) {
exposeInScope(request,name,scope,bean);
}
}
} // end checkData
/**
* Process new dispatch advice passed by the business tier.
* <p>
* This is used to route control to another location besides
* the default "success" forward registered with the controller.
* <p>
* The business tier can pass back either a path or the name of
* an ActionForward.
* <code>checkDispatch</code> will then create an ActionForward to return
* and save it in the request under the SUCCESS token.
* The <code>findSuccess()</code> will check for this attribute
* before returning the controller's default.
*
* @param mapping The ActionMapping used to select this instance
* @param request The HTTP request we are processing
* @param BizResponse The BizResponse we are handling
*/
protected void checkDispatch(
ActionMapping mapping,
HttpServletRequest request,
BizResponse bizResponse) {
String dispatch = bizResponse.getDispatch();
ActionForward forward = null;
if (bizResponse.isDispatchPath()) {
forward = new ActionForward(dispatch);
}
else {
forward = mapping.findForward(dispatch);
}
// Our findSuccess looks for this
request.setAttribute(Tokens.SUCCESS,forward);
} // end checkDispatch
/**
* Check outcome, if any; recurse if container for other outcomes.
*
* @param mapping The ActionMapping used to select this instance
* @param request The HTTP request we are processing
* @param BizResponse The BizResponse we are handling
*/
protected void checkOutcome(
ActionMapping mapping,
HttpServletRequest request,
BizResponse bizResponse) throws Exception {
if (bizResponse!=null) {
servlet.log(Log.HELPER_OUTCOME,Log.DEBUG);
if (bizResponse.isAggregate()) {
// recurse for each BizResponse in collection
Collection collection = (Collection)
bizResponse.getData();
Iterator iterator = collection.iterator();
while (iterator.hasNext()) {
BizResponse nextBizResponse =
(BizResponse) iterator.next();
checkOutcome(mapping,request,nextBizResponse);
}
}
else {
// call extension points for whatever is returned
if (bizResponse.isData())
checkData(mapping,request,bizResponse);
if (bizResponse.isMessages())
checkMessages(mapping,request,bizResponse);
if (bizResponse.isDispatch())
checkDispatch(mapping,request,bizResponse);
}
}
else {
throw new Exception(Log.PROCESS_RESULT_NULL);
}
} // end checkOutcome
// --------------------------------------------------------- Public Methods
/**
* Stores informational messages for display by the presention device.
*
* @param mapping The ActionMapping used to select this instance
* @param request The HTTP request we are processing
* @param bizResponse The BizResponse we are handling
*/
protected void checkMessages(
ActionMapping mapping,
HttpServletRequest request,
BizResponse bizResponse) {
// saveMessages(request,bizResponse.getMessages());
} // end checkMessages
/**
* Return the appropriate ActionForward for error or failure
* conditions.
* First checks for a FAILURE ActionForward stored in the request.
* If an override is not found, returns the result of the
* superclass method.
*
* @param mapping The ActionMapping used to select this instance
* @param form The optional ActionForm bean for this request
* @param request The HTTP request we are processing
* @param response The resonse we are creating
* @return The ActionForward representing FAILURE
* or null if a FAILURE forward has not been specified.
*/
protected ActionForward findFailure(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) {
// Did someone leave us a forward?
ActionForward forward = (ActionForward)
request.getAttribute(Tokens.FAILURE);
if (null==forward) {
// No override, use default
forward = super.findFailure(mapping,form,request,response);
}
else {
// Clear advice from the request
request.setAttribute(Tokens.FAILURE,null);
}
return forward;
} // end findFailure
/**
* Optional extension point for pre-processing.
* Default method does nothing.
* To branch to another URI, return an non-null ActionForward.
* If errors are logged (getErrors() et al),
* default behaviour will branch to findFailure().
*
* @param mapping The ActionMapping used to select this instance
* @param form The optional ActionForm bean for this request
* @param request The HTTP request we are processing
* @param response The resonse we are creating
*/
protected void preProcess(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) {
// Check for cancelled
ActionForward forward = mapping.findForward(Tokens.CANCEL);
if ((null!=forward) && (isCancelled(request))) {
// Our findFailure looks for this
request.setAttribute(Tokens.FAILURE,forward);
// Post cancel error message
ActionErrors errors = getErrors(request,true);
errors.add(ActionErrors.GLOBAL_ERROR,
new ActionError(Tokens.ERROR_CANCEL));
return;
}
// Check for missing token
forward = mapping.findForward(Tokens.GET_TOKEN);
if ((null!=forward) && (!isTokenValid(request))) {
// Our findFailure looks for this
request.setAttribute(Tokens.FAILURE,forward);
// Post token error message
ActionErrors errors = getErrors(request,true);
errors.add(ActionErrors.GLOBAL_ERROR,
new ActionError(Tokens.ERROR_TOKEN));
return;
}
if (null!=forward) {
// reset to guard against duplicate request
resetToken(request);
}
// Check for save token directive (do this last)
forward = mapping.findForward(Tokens.SET_TOKEN);
if (null!=forward) saveToken(request);
} // end preProcess
/**
* Return the appropriate ActionForward for the nominal,
* non-error state.
* First checks for a SUCCESS ActionForward stored in the request.
* If an override is not found, returns the result of the
* superclass method.
*
* @param mapping The ActionMapping used to select this instance
* @param form The optional ActionForm bean for this request (if any)
* @param request The HTTP request we are processing
* @param response The response we are creating
* @return The ActionForward representing SUCCESS
* or null if a SUCCESS forward has not been specified.
*/
protected ActionForward findSuccess(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) {
// Did someone leave us a forward?
ActionForward forward = (ActionForward)
request.getAttribute(Tokens.SUCCESS);
if (null==forward) {
// No override, use default
forward = super.findSuccess(mapping,form,request,response);
}
else {
// Clear advice from the request
request.setAttribute(Tokens.SUCCESS,null);
}
return forward;
} // end findSuccess
/**
* The set of argument type classes for the reflected method call.
* These are the same for all calls, so calculate them only once.
*/
private static final Class types[] = { Object.class };
/**
* Error handler.
* Posts a message template and two parameters in a BizResponse.
*/
private BizResponse processError(
ActionMapping mapping,
String template) {
// Any other way to do this?
BizResponse bizResponse =
new org.apache.commons.scaffold.util.BizResponseImpl();
Message message =
new org.apache.commons.scaffold.util.MessageImpl(
template,
mapping.getPath(),
mapping.getParameter()
);
bizResponse.addMessage(message);
return bizResponse;
}
/**
* Invoke an alternate method on BizService.
*/
protected BizResponse processDispatch(
ActionMapping mapping,
BizService bizService,
BizRequest bizRequest,
String methodName) throws Exception {
Method method = bizService.getClass().getMethod(methodName,types);
Object args[] = { bizRequest };
BizResponse bizResponse = null;
try {
bizResponse = (BizResponse) method.invoke(bizService,args);
}
catch (ClassCastException e) {
bizResponse = processError(mapping,Tokens.ERROR_DISPATCH_RETURN);
}
catch (IllegalAccessException e) {
bizResponse = processError(mapping,Tokens.ERROR_DISPATCH_RETURN);
}
catch (InvocationTargetException e) {
// Rethrow the target exception if possible so that the
// exception handling machinery can deal with it
Throwable t = e.getTargetException();
if (t instanceof Exception) {
throw ((Exception) t);
} else {
bizResponse = processError(mapping,Tokens.ERROR_DISPATCH);
}
}
return bizResponse;
}
/**
* Obtain the business request, invoke the business service,
* and process the outcome.
*
* @param mapping The ActionMapping used to select this instance
* @param form The ActionForm
* @param request The HTTP request we are processing
* @param response The HTTP response we are creating
* @param helpers The object instantiated from type given as parameter.
* @exception Exception if a error occurs
*/
protected void executeLogic(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response,
Object[] helpers) throws Exception {
BizResponse bizResponse = null;
servlet.log(Log.HELPER_PROCESSING,Log.DEBUG);
try {
// Cast our form bean; snag our request bean
BizForm bizForm = (BizForm) form;
BizRequest bizRequest = bizForm.getBizRequest();
// Munge the parameter property
servlet.log(Log.TOKENS_PARSING,Log.DEBUG);
String[] tokens = tokenize(mapping.getParameter());
// Create our business service helper
Object helper = createHelperObject(request,tokens[0]);
BizService bizService = (BizService) helper;
// Process business logic
servlet.log(Log.HELPER_EXECUTING,Log.DEBUG);
if (tokens.length>1) {
// Pass along the helper's parameter, if any
if (tokens.length>2) {
bizRequest.setParameter(tokens[2]);
}
bizResponse = processDispatch(
mapping,
bizService,
bizRequest,
tokens[1]);
}
else {
bizResponse = (BizResponse) bizService.process(bizRequest);
}
}
// Gracefully trap any kinky class-cast or NPE type exceptions
catch (Throwable t) {
throw new ParameterException(t);
}
// Analyze result of business logic
checkOutcome(mapping,request,bizResponse);
} // end executeLogic
} // end BizAction