Pageflow instance variables null.
Hello BEA Experts,
Weblogic documentation states that pageflow can be used to store data that on a per user per session basis , however I have a instance variable string that is being set in the begin action which is called in the beginning of the pagelow.
Later on another action with in the pageflow is called via a hyperlink , inside this action the string variable that was set in the begin action is returning null.
I am surpised as to why Workshop is showing this behaviour.
I use workshop version 8.1.4.
Any comments and suggestions towards resolving this issue would be highly appreciated.
Thanks in advance!
Hi Bob,
This could be because the current pageflow in the session was replaced with another instance. This can happen if you accessed another pageflow or a nested PF during the flow.
You can check it by turning on the debug. Create a file debug.properties and add the entries below into it and save the file in the domain folder.
com.bea.wlw.netui.pageflow.FlowControllerFactory: on com.bea.wlw.netui.pageflow.FlowController: on com.bea.wlw.netui.pageflow.PageFlowUtils: on com.bea.wlw.netui.pageflow.PageFlowStack: on
Restart the server and test the jpf. The output of the debug goes to stdOut of the server.
Vimala-
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import java.io.*;
import java.net.*;
import java.util.*;
import javax.xml.parsers.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;
public class mysax extends DefaultHandler
String ctelement;
CharArrayWriter contents;
String vname1,vrcbreg1,vaddress1,vcountry1,vtelephone1,vfax1;
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vname1 = null;
vrcbreg1 = null;
vaddress1 = null;
vcountry1 = null;
vtelephone1 = null;
vfax1 = null;
contents= new CharArrayWriter();
public void doparse(String url) throws Exception
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
ParserAdapter pa = new ParserAdapter(sp.getParser());
pa.setContentHandler(this);
pa.parse(url);
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public void endElement(String uri,String localName,String qName) throws SAXException
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System.out.println("The exception "+e);
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import java.util.*;
import java.io.*;
import javax.xml.parsers.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;
The SupportMatrix class provides static variables and methods to simplify
the determination of whether or not a given attribute is supported for a
certain object type (queue manager, channel, etc.), depending on the version
and platform of the queue manager to which it belongs.
The SupportMatrix class may not be instantiated. Its constructor is private.
An instance of the class is created internally in the static initializer so
that the XML parsing methods are available.
A corresponding XML document, SupportMatrix.xml, is parsed to create the various
HashMaps which contain the version/platform dependency information. A number of
inner classes are used to represent the various elements of the XML matrix
definition.
Here's a sample document:
<!-- The supportmatrix tag opens the document -->
<supportmatrix>
<!-- Objects are keyed by classid. "1" is the classid of a queue manager object. -->
<object classid="1">
<!-- Versions group attributes according to the queue manager version where they
were introduced. The "base" cmdlevel encompasses all versions up to 5.1. -->
<version cmdlevel="base">
<!-- Attributes are defined by the attr tag. -->
<attr id="MQCA_Q_MGR_NAME">
<!-- Support elements define the platform-specific requirements for an attribute. -->
<support platforms="UNIX,WINDOWS,OS400,VMS,NSK" maxlen="48" type="MQCFST"/>
<support platforms="MVS" maxlen="4" type="MQCFST"/>
</attr>
<attr id="MQCA_Q_MGR_DESC">
<!-- Specific attribute characteristics, most notably maximum len for string parms,
are defined in the support element. As shown in the following example, it may
apply to all platforms. -->
<support platforms="all" maxlen="64" type="MQCFST"/>
</attr>
<!-- Support elements are optional. -->
<attr id="MQIA_PLATFORM"/>
<attr id="MQIA_COMMAND_LEVEL"/>
</version>
<!-- The version element may 'include' other versions. Note that object elements
may also refer to other objects via the 'include' parm of the object tag.
This is to allow common attributes (especially for queues and channels) to
be shared by multiple definitions in order to reduce some of the
redundancy. -->
<version cmdlevel="520" include="base">
</version>
</object>
</supportmatrix>
The inner classes, and their hierarchical relationships are as follows:
SupportObject - corresponds to the <object> element. Stored in a static HashMap, and
keyed by classid.
VersionObject - corresponds to the <version> element. Stored in a HashMap instance
variable of the SupportObject class, keyed by cmdlevel.
AttributeObject - corresponds to the <attr> element. Stored in a HashMap instance
variable of the VersionObject class, keyed by attribute name.
PlatformObject - corresponds to the <support> element. Stored in HashMaps belonging
to the AttributeObjects, keyed by platform. A single PlatformObject
instance is created when the support tag is encountered. The
"platforms" attribute of the support element is then processed. For
each platform in the comma-delimited list, an entry is added to the
collection of PlatformObjects. This is to greatly simplify later
lookups.
In order to support the 'include' feature of object and version elements, certain
functions are recursive. If the attribute to be validated is not found for the passed
cmdlevel, the 'parent' VersionObject is consulted by means of the 'include' value. If
the chain of VersionObjects has been exhausted and the attribute in question has still not
been located, the next SupportObject in the chain is consulted in a similar fashion.
public class SupportMatrix extends DefaultHandler {
/** The objects collection holds all the SupportObjects, keyed by classid. */
private static HashMap objects;
/** xmlFile will name the xml document to be parsed. Note that using the
default class loader expects the string to be the path to the file. It must
NOT begin with the '/' character. */
private static String xmlFile =
ResourceManager.getApplicationProperties().getProperty("SupportMatrixFile");
private Stack stack;
/** This static initializer allocates the static objects collection, creates an
instance of the SupportMatrix class for xml parsing purposes, and initiates
the parse operation to populate the collection. */
static {
objects = new HashMap();
// Create a parser and process the xml doc
SupportMatrix handler = new SupportMatrix();
InputSource is = null;
try {
is = new InputSource(ClassLoader.getSystemClassLoader().getResourceAsStream(xmlFile));
XMLReader xmlReader =
SAXParserFactory.newInstance().newSAXParser().getXMLReader();
xmlReader.setFeature("http://xml.org/sax/features/namespaces", true);
xmlReader.setContentHandler(handler);
if (is == null) {
System.err.println("No input stream, dammit");
xmlReader.parse(is);
} catch(Exception e) {
e.printStackTrace();
/** Private constuctor, used only for XML parsing. */
private SupportMatrix() {
stack = new Stack();
/** Add a SupportObject instance to the objects collection. */
private void addObject(SupportObject obj) {
String key = obj.getClassId();
objects.put(key, obj);
/* DefaultHandler methods */
/** Not used. */
public void characters(char[] ch, int start, int length) {}
/** Not used. */
public void endDocument() {}
/** For the version, object, and attr elements, pop the top element of the stack. */
public void endElement(String uri, String localName, String qName) {
if (localName.equals("version") || localName.equals("object") || localName.equals("attr")) {
stack.pop();
/** Not used. */
public void setDocumentLocator(Locator locator) {}
/** Not used. */
public void startDocument() {}
/** Most of the work is done here. Create the appropriate inner class instance for
element; for object, version, and attr, push the element onto the stack so that
child elements may be added to their collections as needed. */
public void startElement(String uri, String localName, String qName,
Attributes attributes) {
String include = attributes.getValue("include");
if (localName.equals("object")) {
SupportObject obj = new SupportObject(attributes.getValue("classid"), include);
addObject(obj);
stack.push(obj);
} else if ( localName.equals("version")) {
VersionObject ver = new VersionObject(attributes.getValue("cmdlevel"), include);
((SupportObject)stack.peek()).addVersion(ver);
stack.push(ver);
} else if ( localName.equals("attr")) {
AttributeObject a = new AttributeObject(attributes.getValue("id"));
//String desc = StringFactory.getString(attributes.getValue("desc"));
//if(desc != null)
// a.setAttribute();
String readonly = attributes.getValue("readonly");
String exclude = attributes.getValue("exclude");
if (include != null && exclude != null) {
Log.log(Log.ERROR, this, "include and exclude are mutually exclusive, exclude value ignored");
exclude = null;
if (include != null) {
a.setCondition(include, true);
if (exclude != null) {
a.setCondition(exclude, false);
if (readonly != null)
a.setReadonly(readonly.equals("y"));
((VersionObject)stack.peek()).addAttr(a);
stack.push(a);
} else if (localName.equals("support")) {
String platforms = attributes.getValue("platforms");
String readonly = attributes.getValue("readonly");
String maxlen = attributes.getValue("maxlen");
String type = attributes.getValue("type");
int attrType = 0;
if (type != null) {
if (type.equals("MQCFIN")) {
attrType = CMQCFC.MQCFT_INTEGER;
} else if (type.equals("MQCFIL")) {
attrType = CMQCFC.MQCFT_INTEGER_LIST;
} else if (type.equals("MQCFST")) {
attrType = CMQCFC.MQCFT_STRING;
} else if (type.equals("MQCFSL")) {
attrType = CMQCFC.MQCFT_STRING_LIST;
} else if (type.equals("EXBIN")) {
attrType = MqcConstants.EXCFT_BINARY;
} else if (type.equals("EXPCF")) {
attrType = MqcConstants.EXCFT_PCF;
PlatformObject p = null;
if (readonly == null) {
p = new PlatformObject(platforms);
} else {
p = new PlatformObject(platforms, readonly.equals("y"));
String exclude = attributes.getValue("exclude");
if (include != null && exclude != null) {
Log.log(Log.ERROR, this, "include and exclude are mutually exclusive, exclude value ignored");
exclude = null;
if (include != null)
p.setCondition(include, true);
if (exclude != null)
p.setCondition(exclude, false);
if (attrType != 0)
p.setType(attrType);
if (maxlen != null)
p.setLen(Integer.parseInt(maxlen));
((AttributeObject)stack.peek()).addPlatform(p);
public static boolean isExported(int attribute, TopologyModelNode node) {
String name = ResourceManager.getAttributeName(attribute);
return isExported(name, node);
public static boolean isExported(String attribute, TopologyModelNode node) {
// Find the qmgr node to fetch platform and cmdlevel
TopologyModelNode qmgr = node.getModel().getQMgrNode(node.getAddress());
// If there's no qmgr for this node, it must be one of 'ours'.
if (qmgr == null)
return false; // None of 'our' objects can be exported to MQSC.
String classId = node.getClassId();
String cmdLevel = qmgr.getAttributeValue("MQIA_COMMAND_LEVEL");
String platform = qmgr.getAttributeValue("MQIA_PLATFORM");
return isExported(attribute, classId, cmdLevel, platform, node);
public static boolean isExported(int attribute, String classId, String cmdLevel, String platform,
TopologyModelNode node) {
String name = ResourceManager.getAttributeName(attribute);
return isExported(name, classId, cmdLevel, platform, node);
/** Determine if an attribute is exportable. The attribute name, the classid of the object to
which it belongs, plus the command level and platform of the queue manager are all needed
to make this determination.
Start by finding the AttributeObject for the combination of attribute, classid, and
command level. If we can't find the AttributeObject, we assume that the attribute
is not exported. Otherwise, find out if it is exportable for the selected platform.
public static boolean isExported(String attribute, String classId, String cmdLevel, String platform,
TopologyModelNode node) {
AttributeObject attr = getAttributeObject(attribute, classId, cmdLevel);
if (attr == null) {
return false;
} else {
return attr.isExported(platform, node);
public static boolean isSupported(int attribute, TopologyModelNode node) {
String name = ResourceManager.getAttributeName(attribute);
return isSupported(name, node);
public static boolean isSupported(String attribute, TopologyModelNode node) {
// Find the qmgr node to fetch platform and cmdlevel
TopologyModelNode qmgr = node.getModel().getQMgrNode(node.getAddress());
// If there's no qmgr for this node, it must be one of 'ours'.
if (qmgr == null)
return true;
String classId = node.getClassId();
String cmdLevel = qmgr.getAttributeValue("MQIA_COMMAND_LEVEL");
String platform = qmgr.getAttributeValue("MQIA_PLATFORM");
return isSupported(attribute, classId, cmdLevel, platform);
public static boolean isSupported(int attribute, String classId, String cmdLevel, String platform) {
String name = ResourceManager.getAttributeName(attribute);
return isSupported(name, classId, cmdLevel, platform);
/** Determine if an attribute is supported. The attribute name, the classid of the object to
which it belongs, plus the command level and platform of the queue manager are all needed
to make this determination.
Start by finding the SupportObject for the classid. If it isn't there, we make the assumption
(for now) that the attribute is supported. The only classids for which this can occur are
broker, agent, and the various container objects.
Propagate the isSupported request to the chain of SupportObjects (based on 'include' values)
until we get a 'true' result or we run out of SupportObjects. */
public static boolean isSupported(String attribute, String classId, String cmdLevel, String platform) {
if (attribute == null)
return false;
SupportObject obj = (SupportObject)objects.get(classId);
// If the object type isn't even in the support matrix, we interpret that to
// mean that it's a Broker or Agent, in which case all attributes are supported
// at present.
if (obj == null)
return true;
boolean result = false;
while (result == false && obj != null) {
result = obj.isSupported(attribute, cmdLevel, platform);
if (result == false && obj.getInclude() != null) {
obj = (SupportObject)objects.get(obj.getInclude());
} else
obj = null;
return result;
/** Locate an AttributeObject for a given attribute name, object type, and command level.
This is a helper function for the getMaxLen and getType methods. */
private static AttributeObject getAttributeObject(String attr, String classID, String cmdLevel) {
AttributeObject result = null;
SupportObject obj = (SupportObject)objects.get(classID);
while (result == null && obj != null) {
result = obj.getAttr(attr, cmdLevel);
if (result == null && obj.getInclude() != null) {
obj = (SupportObject)objects.get(obj.getInclude());
} else
obj = null;
return result;
/** Determine the maximum length for a given combintation of attribute name, object type,
command level, and platform. If the AttributeObject can't be found, or if the length
hasn't been set, return -1. */
public static int getMaxLen(String attr, String classId, String cmdLevel, String platform) {
AttributeObject a = getAttributeObject(attr, classId, cmdLevel);
if (a == null)
return -1;
return a.getMaxLen(platform);
/** Determine the PCF parm type for a given combintation of attribute name, object type,
command level, and platform. If the AttributeObject can't be found, or if the length
hasn't been set, return -1. */
public static int getType(String attr, String classId, String cmdLevel, String platform) {
AttributeObject a = getAttributeObject(attr, classId, cmdLevel);
if (a == null)
return -1;
return a.getType(platform);
/** Inner class to contain platform-specific info for an attribute. */
class PlatformObject {
/** This instance variable will contain the comma-delimited string of all
platforms to which this object applies. */
private String platform;
private int maxlen;
private String condition = null;
private boolean include;
private boolean readonly;
private boolean lenSet;
private int attrType;
private boolean typeSet;
public PlatformObject(String p, boolean readonly) {
platform = p;
this.readonly = readonly;
lenSet = false;
typeSet = false;
public PlatformObject(String p) {
this(p, false);
public void setCondition(String condition, boolean include) {
this.condition = condition;
this.include = include;
public boolean isReadonly() {
return readonly;
public boolean isExported(TopologyModelNode node) {
if (condition != null) {
boolean test = false;
try {
test = Utilities.evaluateCondition(node, condition);
} catch (Exception e) {}
if (include ^ test)
return false;
return !readonly;
public void setLen(int len) {
maxlen = len;
lenSet = true;
public void setType(int type) {
attrType = type;
typeSet = true;
public String getPlatform() {
return platform;
public int getMaxLen() {
if (!lenSet)
return -1;
return maxlen;
public int getType() {
if (!typeSet)
return -1;
return attrType;
/** This class represents a specific MQSeries attribute. It can optionally contain
instances of the PlatformObject class as needed. When the 'platforms' collection
is empty, the attribute is supported on all platforms. It is also possible to
include a PlatformObject for the 'all' platform, if specific attribute characteristics
need representation. When the 'platforms' collection is non-empty, it will include one
entry for each platform where the attribute is supported. */
class AttributeObject {
private String attribute;
private String attrValue;
private HashMap platforms;
private String condition = null;
private boolean include;
private boolean readonly = false;
public AttributeObject(String a) {
this(a, false);
public AttributeObject(String a, boolean readonly) {
attribute = a;
platforms = new HashMap();
this.readonly = readonly;
public void setCondition(String condition, boolean include) {
this.condition = condition;
this.include = include;
public void setReadonly(boolean readonly) {
this.readonly = readonly;
public boolean isReadonly() {
return readonly;
public void addPlatform(PlatformObject p) {
for (StringTokenizer st = new StringTokenizer(p.getPlatform(), ","); st.hasMoreTokens() ;) {
platforms.put(st.nextToken(), p);
public PlatformObject getPlatform(String platform) {
PlatformObject p = (PlatformObject)platforms.get(platform);
if (p == null)
p = (PlatformObject)platforms.get("all");
return p;
public String getAttribute() {
return attribute;
public int getMaxLen(String platform) {
PlatformObject p = getPlatform(platform);
if (p == null)
return -1;
return p.getMaxLen();
public int getType(String platform) {
PlatformObject p = getPlatform(platform);
if (p == null)
return -1;
return p.getType();
public boolean isSupported(String platform) {
if (platforms.isEmpty()) {
return true;
if (platforms.containsKey(platform)) {
return true;
if (platforms.containsKey("all")) {
return true;
return false;
public boolean isExported(String platform, TopologyModelNode node) {
if (readonly) {
Log.log(Log.DEBUG, this, attribute + " is readonly, returning false");
return false;
if (condition != null) {
Log.log(Log.DEBUG, this, "Testing condition = " + condition);
boolean test = false;
try {
test = Utilities.evaluateCondition(node, condition);
Log.log(Log.DEBUG, this, "Condition result is " + test);
} catch (Exception e) {
Log.log(Log.ERROR, this, "Condition through an exception");
if (include ^ test)
return false;
if (platforms.isEmpty()) {
return true;
PlatformObject p = getPlatform(platform);
if (p == null) {
Log.log(Log.DEBUG, this, platform + " not found for " + attribute + ", returning false");
return false;
return p.isExported(node);
/** This class represents a specific value of a queue manager's command level. A
given instance of this class may 'include' a 'parent' instance through its
include instance variable. The traversal of the parent/child hierarchy is
delegated to the SupportObject class, since that is where the collection of
VersionObjects lives. */
class VersionObject {
private String cmdLevel;
private String include;
private HashMap attributes;
public VersionObject(String cmdLevel, String include) {
this.cmdLevel = cmdLevel;
this.include = include;
attributes = new HashMap();
public void addAttr(AttributeObject attr) {
attributes.put(attr.getAttribute(), attr);
public AttributeObject getAttr(String attr) {
return (AttributeObject)attributes.get(attr);
public String getCmdLevel() {
return cmdLevel;
public String getInclude() {
return include;
public boolean isSupported(String attr, String platform) {
AttributeObject obj = (AttributeObject)attributes.get(attr);
if (obj == null) {
return false;
} else
return obj.isSupported(platform);
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queue manager or local queue. This class implements an include facility similar to
that described for the VersionObject. The traversal of that hierarchy is delegated
to the static isSupported method, because the collection of SupportObject instances
is a static variable of the SupportMatrix class. */
class SupportObject {
private String classId;
private String include;
private HashMap versions;
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this.classId = classId;
this.include = include;
versions = new HashMap();
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versions.put(key, obj);
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obj = (VersionObject)versions.get("base");
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return false;
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result = obj.isSupported(attr, platform);
if (result == false && obj.getInclude() != null) {
obj = (VersionObject)versions.get(obj.getInclude());
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obj = null;
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AttributeObject result = null;
VersionObject obj = (VersionObject)versions.get(cmdLevel);
if (obj == null)
obj = (VersionObject)versions.get("base");
// I don't actually know what it means if obj is null at this point.
// It probably can't happen.
if (obj == null)
return null;
while (result == null && obj != null) {
result = obj.getAttr(attr);
if (result == null && obj.getInclude() != null)
obj = (VersionObject)versions.get(obj.getInclude());
else
obj = null;
return result;
}Are you the one who commented out the code you're looking for ?//String desc = StringFactory.getString(attributes.getValue("desc"));You just have to modify you AttributeObject class to hold a new field : String description. And then, it's up to you to create a new constructor or a new setter method.
Btw, this is not a Swing related question. -
How can I use evaluate to get the instance variable in customized tag
1.
At first , I create a class called bean,and declared several params in it and do not define any getter function for the param.
class bean{
String param = "test";
SomeClass scObj = new SomeClass();
2.
The second ,I use
request.setAttribute("beanObj",new bean());
3.
And then I wanna use the customized tag to show a text box , then initialize it's value.
<salt:text name="param" value="beanObj.param">
<salt:text name="obj" value="beanObj.scObj.func()">
4.
I tried the evaluator provided by JexlContext ,Struts, JSTL and it seems that if I do not define the getter for the variable ,I can not get the bean's instance variable's value.
Expression e = ExpressionFactory.createExpression( value );
JexlContext jc = JexlHelper.createContext();
jc.getVars().put(strInitBeanName, request.getAttribute("beanObj"));
Object obj = e.evaluate(jc);
the result of the obj is null....
Can anybody recommand some other evaluator can get the value of a instance variable from an object?do you have any other suggestion ? Nops, somebody else may have though. AFAIK, all lookups of the type
beanName.propertyNameuse reflection on the getXXX() methods to access the property.
Having said that, I guess you could write one though in a custom tag, using the same - reflection (you will ahve to rely on the java.lang.reflect.Field class quite heavily) - but that would be reinventing the wheel for most other functionality that you would have to include (like looking up the bean in scope etc)
cheers,
ram. -
I have some questions about JSP presentation (Interactive Component Call in Screenflow):
- Only BPM Objects are possible to be mapped in JSP?
- Is possible to map two or more BPM Objects to the JSP?
- What is the difference of mapping using the variable "attributes" in argument mapping and the option "Select BPM object variable" in main task of Interactive Component Call activity?I seem to be having a similar problem.
If I include this fragment, for an instance variable called "contacts" which is a BPMObject of type "ITSSContactRequest".
<%
Object r = request.getAttribute("contacts");
Class cl = r.getClass();
out.println(cl.getName());
%>
I get the following output:
xobject.ITSSContactManagement.ITSSContactRequest
and I can access the object via reflection:
<%
Object r = request.getAttribute("contacts");
Class cl = r.getClass();
out.println(cl.getName());
Method getGeneralContacts = cl.getMethod("getGeneralContacts", null);
Object rv = getGeneralContacts.invoke(r);
%>
and access the rv variable accordingly.
However, if I try and cast the variable directly:
<%
Object r = request.getAttribute("contacts");
Class cl = r.getClass();
out.println(cl.getName());
xobject.ITSSContactManagement.ITSSContactRequest rq = (xobject.ITSSContactManagement.ITSSContactRequest)r;
%>
I get the following error message:
"The task could not be successfully executed. Reason: 'fuego.web.execution.exception.InternalForwardException: UnExpected error during internal forward process.'.
See log file for more information [Error code: workspace-1258985548580] "
The same error occurs if I try and import the object via
<%@ page import="xobject.ITSSContactManagement.ITSSContactRequest" %>
Thanks for any help. -
Stateful session bean destroying instance variables?
I'm trying to use a stateful session bean as some kind of login controller and to maintain the login id and access level across JSPs and HTMLs so that once logged in, all the JSPs can obtain the login name of the current user (String) and his access level (int).
I use the login.jsp to login and it successfully reports logging in with the correct access level retrieved from database. However, if I go to another JSP (testlogin.jsp), these 2 EJB instance variables are always destroyed and set to null and 0 when I access them again.
What am I missing that my stateful session bean is not saving these instance variables? Do I need to put them in some serializable value objects (create a help VO class?)
I suspected that on different JSP, I call the MemberControllerHome.create() method, it creates a new instance or something but if I don't use the create method how do I get a handle to MemberController at all?
MemberControllerBean.java
public class MemberControllerBean implements SessionBean {
//initialize in ejbCreate.
private MemberHome memberHome;
SessionContext context;
//Member currentLogin;
//Current Login
private String loginID;
private int accessLevel;
// Constructor
public MemberControllerBean() {}
...some code in between...
public void login(String id, String password){
try{
Member member = null;
member = memberHome.findByPrimaryKey(id);
if(member.getMPassword().equals(password)){
this.loginID = member.getMID();
this.accessLevel = member.getMAccessLevel();
else{
throw new EJBException("Login failed. Invalid member ID and/or password.");
} catch (FinderException ex) {
throw new EJBException("Login failed. Invalid member ID and/or password.");
public void logout(){
this.loginID = null;
this.accessLevel = 4;
public String getLoginID(){
return this.loginID;
public int getLoginAccessLevel(){
return this.accessLevel;
login.jsp
String mID = request.getParameter("mID");
String mPassword = request.getParameter("mPassword");
out.println("20:" + mID + ":" + mPassword);
if(mID != null && mPassword != null){
out.println("22:" + mID + ":" + mPassword);
try{
InitialContext ic = new InitialContext();
MemberControllerHome home = (MemberControllerHome) ic.lookup("java:comp/env/ejb/MemberController");
MemberController mc = home.create();
out.println("26:Logging in as " + mID + " with " + mPassword);
mc.login(mID, mPassword);
out.println("28:" + mc.getLoginID() + "logged in successfully at level " +
mc.getLoginAccessLevel() + ".");
} catch (NamingException ex) {
out.println("java:comp/env/ejb/MemberController not found.");
} catch (EJBException ex) {
out.println(ex.getMessage());
} catch (Exception ex) {
out.println(ex.getMessage());
testlogin.jsp
<%
try{
InitialContext ic = new InitialContext();
MemberControllerHome home = (MemberControllerHome) ic.lookup("java:comp/env/ejb/MemberController");
MemberController mc = home.create();
out.println("You are logged in as <b>" + mc.getLoginID() +
"</b> at level <b>" + mc.getLoginAccessLevel() + "</b>.");
} catch (NamingException ex) {
out.println("java:comp/env/ejb/MemberController not found.");
} catch (EJBException ex) {
out.println(ex.getMessage());
} catch (Exception ex) {
out.println(ex.getMessage());
%>The key to the problem is that in testlogin.jsp a new stateful session bean is created. The new bean instance of course doesn't know the log-in information you stored in the old session bean. That is why the method returns null and 0 when called.
There are couple of ways to solve the issue. The easiest solution is to store the bean instance created in Login.jsp in the jsp's implicit HttpSession object. Because login.jsp and testlogin.jsp share the same session, the bean instance can be easily stored and retrieved.
Here is the code you need to have:
1. in login.jsp
session.setAttribute("MemberControllerBeanInstance", mc);
2. in testlogin.jsp
MemberController mc =
(MemberController) session.getAttribute("MemberControllerBeanInstance");
Hope it helps. -
Can i use instance variables in page flow controller with out restriction?
I am using instance variable in pageflow controller.
1) Will it give any problem if concurrent users are accessing that controller class?
2) How many controller objects will be created if multiple users (Say 10 users) accessing same controller class?
Thanks.1) Will it give any problem if concurrent users are accessing that controller class? Pageflows are pere user session, different users wont cause it problems. however a single user can cause problems by using open new tab on a link etc(or back button or refresh on browser, problems with using state in a stateless protocol) . A bigger problem is that since a pageflow is indirect in session, using private variables in pageflow increases your session footprint and in a cluster , if replicated, your network trafiic as well. Using state also causes problem in HTTP , a stateless protocol,. Highly not recommended (unless you have no other choice)
2) How many controller objects will be created if multiple users (Say 10 users) accessing same controller class? 10. assuming the portlet is used once only. If you use the same portlet in multiple pages , then you have that many.
Edited by: deepshet on Feb 27, 2010 12:10 PM -
How to clone generic instance variables?
Hi guys,
If I have private class Item<T>
private T value;
private int priority;
public Item(T value, int priority)
this.value = value;
this.priority = priority;
@Override
public Object clone()
try
Item copy = (Item)super.clone();
copy.value = (T)value.clone(); //compiler errors, says: "clone has protected access in java.lang.Object"
return copy;
catch (CloneNotSupportedException e)
return null;
}So if the instance variable is of mutable type e.g. Person, how can I make sure that value.clone() is called on a Person object?[http://www.angelikalanger.com/GenericsFAQ/FAQSections/ProgrammingIdioms.html#FAQ502|http://www.angelikalanger.com/GenericsFAQ/FAQSections/ProgrammingIdioms.html#FAQ502]
-
Inheritance - instance variable initialization
Hi all.
I have a question regarding inherited instance variables.
class Animal {
int weight;
int age = 10;
class Dog extends Animal {
String name;
class Test {
public static void main(String[] args) {
new Dog();
}This is just an arbitrary code example.
When new Dog() is invoked, I understand that it's instance variable "name" is give the default
type value of null before Dog's default constructor's call to super() is invoked.But Im a little perplexed about
Animals instance variables. I assume that like Dog, Animals instance variables are given their default type values
of 0 & 0 respectively, before Animals invocation of super(); What im unclear about is that at the point that weight and age are given their default type values, are Dog's inherited weight and age variables set to 0 aswell at that exact moment? Or are Dog's inherited weight and age variables only assigned their values after Animals constructor fully completes because initialization values are only assigned to a classes instance variables after it's call to super().
Many thanks & best regards.Boeing-737 wrote:
calvino_ind wrote:
Boeing-737 wrote:
newark wrote:
why not throw in some print statements and find out?Super() or this() have to be the very first statement in a constructor..
Also you cannot access any instance variables until after super or this.
:-S
Kind regardsbut if you add the "print" statement in animal constructor, you can easily see what happened to the attributes of Dog ; that s the trick to print "before" super()You can never add a print before super(). It's a rule of thumb, super() and this() must always be the first statements
in a constructor, whether added implicitly by the compiler or not. In this case there are 2 default constructors (inserted by the compiler), each with a super() invocation. Even if i added them myself and tried to print before super(), the compiler would complain.
Thanks for the help & regards.you didn't understand what i meant ; take a look at that:
class Animal {
int weight;
int age = 10;
public Animal() {
Dog thisAsADog = (Dog) this;
System.out.println(thisAsADog.name);
System.out.println(thisAsADog.x);
class Dog extends Animal {
String name;
int x = 10;
public class Test {
public static void main(String[] args) {
new Dog();
}this way you will know what really does happen -
Inheritance and private instance variables
I've been reading a Java book. It says you should normally make your instance variables private and use getter/setter methods on them, but if you create a superclass, you have to make those variables public (or default?) to inherit them in the subclasses, right? And you can't redefine the variables as private in the subclass, can you?
I'm a little confused on this point. Thanks for any light anyone could shed on this.
=====
Nevermind...I think I figured it out!
Message was edited by:
NovaKaneThanks to both of you for your responses. I think I've pretty much done what you did, Anan, in this little test program.
public class Animal
private String name=null;
public void setName(String n)
name=n;
public String getName()
return name;
public void makeSound()
public class Dog extends Animal
public void makeSound()
if (getName() !=null)
System.out.println(getName()+" says, \"Bow Wow!\"");
else
System.out.println("I don't have a name...but \"Bow Wow!\"");
public class Cat extends Animal
public void makeSound()
if (getName() != null)
System.out.println(getName()+" says, \"Meow!\"");
else
System.out.println("I have no name...but, \"Meow!\"");
import java.util.*;
public class Test
public static void main(String[] vars)
ArrayList<Animal> animals = new ArrayList<Animal>();
Animal d = new Dog();
Animal c = new Cat();
d.setName("Fido");
c.setName("Fluffy");
animals.add(d);
animals.add(c);
for (Animal a : animals)
a.makeSound();
}The "name" instance variable is private, but I can get at it through the getter/setter methods of the superclass, which are public. I should NOT be able to say something like...
d.name="Fido";Right? -
Just out of interest :
If I have an instance variable that is an object, should I set it equal to null and then instantiate it in the constructor:
class MyClassA{
MyClassB b = null;
MyClassA(){
b = new MyClassB();
OR
should I just instantiate it when I declare it?
class MyClassA{
MyClassB b = new MyClassB();
}Is there a standard for this?Package-private is the default for member variables.
Second google result for java default access modifier:
http://java.sun.com/docs/books/jls/second_edition/html/names.doc.html -
Initializing instance variables in a constructor that are used by super()
I have a class that extends a standard class (ie JButton, but it doesn't matter what class). The constructor takes a parameter that I set to an instance variable. There is an overloaded method of the standard class that needs to use the variable.
My problem is that since I must call super() first, my instance variable is not yet set, so when my overloaded method is called by the constructor it is unable to see the paramater value. How can my method see this value?
public class MyClass extends somejavaclass {
MyClass(int x) {
super();
myInt = x;
// This overrides something in somejavaclass and is called by the constructor
public void aJavaMethod() {
// do some logic with myInt, but it has not been set to my paramater value
int myInt;
}If the variable in question is an object reference,
you could compare it to null. A true result would tell
you that it hadn't been initialized yet, and you could
write code to behave accordingly (for example calling
the init() method to do the initialization).That's a good solution but what if the instance in question is set in the sub-classes constructor?
This is a very annoying feature of Java, and one that
I have had to work around on several occasions. And as
far as I'm concerned it's an unnecessary feature: why
shouldn't a class be able to initialize its variables
before it calls the superclass's constructor? Other OO
languages permit that.I've wondered this also. I'd always assumed it was a way to make sure the super-class was completely initialized before anything tries to use it esp. to make sure the Object() constructor is finished before anything else happens.
How is this dealt with in C++ or does it just leave open potential for errors? -
Page flow controller - instance variable thread safe?
I have page flow controller that is a subclass of org.apache.beehive.netui.pageflow.PageFlowController runing weblogic 921. The essence of my question is: is instance variable of page flow controller thread safe?
Here are the details. I have an instance variable “status” that stores the status of the patient, which is stored in the request. It sets the status with after the patient status is retrieved from database. The set method is not synchronized.
This works fine during normal test. But it failed during load test. Does a page flow controller instance shared among different requests? If so, how can I store the status for each request?
Thanks,
G THello
You seem to put your question on the wrong forum
Oracle Beehive and Apache Beehive are two different products...
Have a look on http://beehive.apache.org
Cheers
Fred
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