Custom OgnlValueStack in Struts 2 - struts2

Question

I want to implement a custom ValueStack in my application by extending the OgnlValueStack class of Struts 2.3.x.
Please let me know how to accomplish this. What classes do I need to extend and implement in my application and how to inject different dependencies using the #Inject annotation?
Update
I have made the changes as suggested earlier. My ValueStackFactory implementation is:
package jp.co.spectrum.insight.core.mvc.factory;
import java.util.Map;
import java.util.Set;
import jp.co.spectrum.insight.core.datamodel.InsightValueStackImpl;
import ognl.MethodAccessor;
import ognl.OgnlRuntime;
import ognl.PropertyAccessor;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.TextProvider;
import com.opensymphony.xwork2.conversion.NullHandler;
import com.opensymphony.xwork2.conversion.impl.XWorkConverter;
import com.opensymphony.xwork2.inject.Container;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.ognl.OgnlNullHandlerWrapper;
import com.opensymphony.xwork2.ognl.accessor.CompoundRootAccessor;
import com.opensymphony.xwork2.util.CompoundRoot;
import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.ValueStackFactory;
public class InsightValueStackFactory implements ValueStackFactory {
#Inject
private XWorkConverter xworkConverter;
private CompoundRootAccessor compoundRootAccessor;
#Inject("system")
private TextProvider textProvider;
#Inject
private Container container;
private boolean allowStaticMethodAccess;
/*
private static ValueStackFactory instance;
public static ValueStackFactory getInstance() {
if (instance == null) {
instance = new InsightValueStackFactory();
}
return instance;
}
*/
private static ValueStackFactory factory = new InsightValueStackFactory();
public static void setFactory(ValueStackFactory factoryParam) {
factory = factoryParam;
}
public static ValueStackFactory getFactory() {
return factory;
}
public void setXWorkConverter(XWorkConverter conv) {
this.xworkConverter = conv;
}
public void setTextProvider(TextProvider textProvider) {
this.textProvider = textProvider;
}
#Inject(value="allowStaticMethodAccess", required=true)
public void setAllowStaticMethodAccess(String allowStaticMethodAccess) {
this.allowStaticMethodAccess = "true".equalsIgnoreCase(allowStaticMethodAccess);
}
public ValueStack createValueStack() {
ValueStack stack = new InsightValueStackImpl(xworkConverter, compoundRootAccessor, textProvider, allowStaticMethodAccess);
container.inject(stack);
stack.getContext().put(ActionContext.CONTAINER, container);
return stack;
}
public ValueStack createValueStack(ValueStack stack) {
ValueStack result = new InsightValueStackImpl(stack, xworkConverter, compoundRootAccessor, allowStaticMethodAccess);
container.inject(result);
stack.getContext().put(ActionContext.CONTAINER, container);
return result;
}
public void setContainer(Container container) throws ClassNotFoundException {
Set<String> names = container.getInstanceNames(PropertyAccessor.class);
for (String name : names) {
Class cls = Class.forName(name);
if (cls != null) {
if (Map.class.isAssignableFrom(cls)) {
PropertyAccessor acc = container.getInstance(PropertyAccessor.class, name);
}
OgnlRuntime.setPropertyAccessor(cls, container.getInstance(PropertyAccessor.class, name));
if (compoundRootAccessor == null && CompoundRoot.class.isAssignableFrom(cls)) {
compoundRootAccessor = (CompoundRootAccessor) container.getInstance(PropertyAccessor.class, name);
}
}
}
names = container.getInstanceNames(MethodAccessor.class);
for (String name : names) {
Class cls = Class.forName(name);
if (cls != null) {
OgnlRuntime.setMethodAccessor(cls, container.getInstance(MethodAccessor.class, name));
}
}
names = container.getInstanceNames(NullHandler.class);
for (String name : names) {
Class cls = Class.forName(name);
if (cls != null) {
OgnlRuntime.setNullHandler(cls, new OgnlNullHandlerWrapper(container.getInstance(NullHandler.class, name)));
}
}
if (compoundRootAccessor == null) {
throw new IllegalStateException("Couldn't find the compound root accessor");
}
this.container = container;
}
}
The InsightValueStackImpl class is my customized ValueStack and it extends the OgnlValueStack.
After the changes as suggested earlier, when I start the application, I get the following error:
java.lang.IllegalArgumentException: Wrapped type converter cannot be null
at com.opensymphony.xwork2.ognl.OgnlTypeConverterWrapper.<init>(OgnlTypeConverterWrapper.java:32)
at com.opensymphony.xwork2.ognl.OgnlValueStack.setRoot(OgnlValueStack.java:88)
at com.opensymphony.xwork2.ognl.OgnlValueStack.<init>(OgnlValueStack.java:71)
at jp.co.spectrum.insight.core.datamodel.InsightValueStackImpl.<init>(InsightValueStackImpl.java:86)
at jp.co.spectrum.insight.core.mvc.factory.InsightValueStackFactory.createValueStack(InsightValueStackFactory.java:85)
at jp.co.spectrum.insight.core.mvc.dispatcher.InsightFilterDispatcher.<init>(InsightFilterDispatcher.java:118)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at java.lang.Class.newInstance0(Class.java:355)
at java.lang.Class.newInstance(Class.java:308)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:275)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4072)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4726)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
at org.apache.catalina.core.StandardService.start(StandardService.java:525)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
This is because of null XWorkConverter instance.
Please let me know why it is not getting injected.
Thanks in advance
Thanks
I have made the changes as suggested earlier.
My ValueStackFactory implementation is:
package jp.co.spectrum.insight.core.mvc.factory;
import java.util.Map;
import java.util.Set;
import jp.co.spectrum.insight.core.datamodel.InsightValueStackImpl;
import ognl.MethodAccessor;
import ognl.OgnlRuntime;
import ognl.PropertyAccessor;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.TextProvider;
import com.opensymphony.xwork2.conversion.NullHandler;
import com.opensymphony.xwork2.conversion.impl.XWorkConverter;
import com.opensymphony.xwork2.inject.Container;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.ognl.OgnlNullHandlerWrapper;
import com.opensymphony.xwork2.ognl.accessor.CompoundRootAccessor;
import com.opensymphony.xwork2.util.CompoundRoot;
import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.ValueStackFactory;
public class InsightValueStackFactory implements ValueStackFactory {
#Inject
private XWorkConverter xworkConverter ;
private CompoundRootAccessor compoundRootAccessor ;
#Inject("system")
private TextProvider textProvider ;
#Inject
private Container container;
private boolean allowStaticMethodAccess;
/*private static ValueStackFactory instance;
public static ValueStackFactory getInstance(){
if(instance==null){
instance = new InsightValueStackFactory();
}
return instance;
}*/
private static ValueStackFactory factory = new InsightValueStackFactory();
public static void setFactory(ValueStackFactory factoryParam) {
factory = factoryParam;
}
public static ValueStackFactory getFactory() {
return factory;
}
public void setXWorkConverter(XWorkConverter conv) {
this.xworkConverter = conv;
}
public void setTextProvider(TextProvider textProvider) {
this.textProvider = textProvider;
}
#Inject(value="allowStaticMethodAccess", required=true)
public void setAllowStaticMethodAccess(String allowStaticMethodAccess) {
this.allowStaticMethodAccess = "true".equalsIgnoreCase(allowStaticMethodAccess);
}
public ValueStack createValueStack() {
ValueStack stack = new InsightValueStackImpl(xworkConverter, compoundRootAccessor, textProvider, allowStaticMethodAccess);
container.inject(stack);
stack.getContext().put(ActionContext.CONTAINER, container);
return stack;
}
public ValueStack createValueStack(ValueStack stack) {
ValueStack result = new InsightValueStackImpl(stack, xworkConverter, compoundRootAccessor, allowStaticMethodAccess);
container.inject(result);
stack.getContext().put(ActionContext.CONTAINER, container);
return result;
}
public void setContainer(Container container) throws ClassNotFoundException {
Set<String> names = container.getInstanceNames(PropertyAccessor.class);
for (String name : names) {
Class cls = Class.forName(name);
if (cls != null) {
if (Map.class.isAssignableFrom(cls)) {
PropertyAccessor acc = container.getInstance(PropertyAccessor.class, name);
}
OgnlRuntime.setPropertyAccessor(cls, container.getInstance(PropertyAccessor.class, name));
if (compoundRootAccessor == null && CompoundRoot.class.isAssignableFrom(cls)) {
compoundRootAccessor = (CompoundRootAccessor) container.getInstance(PropertyAccessor.class, name);
}
}
}
names = container.getInstanceNames(MethodAccessor.class);
for (String name : names) {
Class cls = Class.forName(name);
if (cls != null) {
OgnlRuntime.setMethodAccessor(cls, container.getInstance(MethodAccessor.class, name));
}
}
names = container.getInstanceNames(NullHandler.class);
for (String name : names) {
Class cls = Class.forName(name);
if (cls != null) {
OgnlRuntime.setNullHandler(cls, new OgnlNullHandlerWrapper(container.getInstance(NullHandler.class, name)));
}
}
if (compoundRootAccessor == null) {
throw new IllegalStateException("Couldn't find the compound root accessor");
}
this.container = container;
}
}
The InsightValueStackImpl class is my customized ValueStack and it extends the OgnlValueStack.
After the changes as suggested earlier, when I start the application, I get the following error:
java.lang.IllegalArgumentException: Wrapped type converter cannot be null
at com.opensymphony.xwork2.ognl.OgnlTypeConverterWrapper.(OgnlTypeConverterWrapper.java:32)
at com.opensymphony.xwork2.ognl.OgnlValueStack.setRoot(OgnlValueStack.java:88)
at com.opensymphony.xwork2.ognl.OgnlValueStack.(OgnlValueStack.java:71)
at jp.co.spectrum.insight.core.datamodel.InsightValueStackImpl.(InsightValueStackImpl.java:86)
at jp.co.spectrum.insight.core.mvc.factory.InsightValueStackFactory.createValueStack(InsightValueStackFactory.java:85)
at jp.co.spectrum.insight.core.mvc.dispatcher.InsightFilterDispatcher.(InsightFilterDispatcher.java:118)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at java.lang.Class.newInstance0(Class.java:355)
at java.lang.Class.newInstance(Class.java:308)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:275)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
at org.apache.catalina.core.ApplicationFilterConfig.(ApplicationFilterConfig.java:115)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4072)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4726)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
at org.apache.catalina.core.StandardService.start(StandardService.java:525)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
This is because of null XWorkConverter instance.
Please let me know why it is not getting injected.
Thanks in advance

Answer 1

You need to implement a ValueStackFactory and register it in your struts.xml, as follows:
<bean type="com.opensymphony.xwork2.util.ValueStackFactory"
name="yourOgnlValueStackFactory"
class="com.example.YourOgnlValueStackFactory" />
Then, set your implementation as the factory to use, using:
<constant name="struts.valueStackFactory" value="yourOgnlValueStackFactory"/>
Update
I'm not sure if you are able to mix field and method injection like you are doing. Try moving the #Inject annotations back to the setter methods and see if that resolves the issue.