java

Use argument in EL expression

There is couple ways about doing that, you could use JBoss EL expression implementation they support method calls with parameters check out Seam, or use similar approach as @digitaljoel suggested.
This is what I created for that purpose, you can call static and static methods, not a great solution but it does the job.

    <c:if  test="#{t:call(null, '@Util.SecurityUtility', 'isPanelWorkbookEnabledForUser','')}">
          Hello Panel    
      </c:if>

@Util is just an alias to com.mycomp.util where

**Example 2**

    <c:if test="#{item != null and  t:call(item, 'java.lang.String', 'indexOf', t:params(t:param('flash-alert',''))) == 0}">                
        #{t:call(session, 'org.apache.catalina.session.StandardSessionFacade', 'removeAttribute', t:params(t:param(item,'')))}      
    </c:if>

t:call, t:params, t:param are function defined in project-taglib.xml as so

    	<function>
		<function-name>call</function-name>
		<function-class>util.Functions</function-class>
		<function-signature>java.lang.Object call(java.lang.Object, java.lang.String, java.lang.String, java.lang.Object[])</function-signature>
	</function>
	<function>
		<function-name>param</function-name>
		<function-class>.util.Functions</function-class>
		<function-signature>java.lang.String param(java.lang.Object, java.lang.String)</function-signature>
	</function>	
 
	<function>
		<function-name>params</function-name>
		<function-class>util.Functions</function-class>
		<function-signature>java.lang.Object[] params(java.lang.String)</function-signature>
	</function>

Here is the implementation

    package mycompany.web.util;
 
import java.beans.XMLDecoder;
import java.beans.XMLEncoder;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.io.StringWriter;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
 
import javax.el.MethodNotFoundException;
 
 
public class Functions {
 
	private  static HashMap<String, String> alliasMap;
	static{
		alliasMap=new HashMap<String, String>();
		alliasMap.put("@DateUtil", "com.americanbanksystems.compliance.util.DateUtil");
		//Match anything following the dot(.)
		alliasMap.put("@Util.*", "com.americanbanksystems.compliance.util");
 
		alliasMap.put("@Application.*", "com.americanbanksystems.compliance.application");
 
	}
 
 
 
 
	public static String param(Object obj, String cls) {	
		//make sure that passed in object is not null
		if(obj==null){
			obj="";
		}
 
		ByteArrayOutputStream baut=new ByteArrayOutputStream();
		XMLEncoder encoder=new XMLEncoder( baut );
		//Bug in the JDK
		//http://bugs.sun.com/bugdatabase/view_bug.do;jsessionid=c993c9a3160fd7de44075a2a1fa?bug_id=6525396
		if(obj instanceof java.sql.Timestamp){
			Date o = new Date(((java.sql.Timestamp)obj).getTime());
			obj=o;
		}		
		//Checking if this is possible 
		if(String.class.isAssignableFrom(obj.getClass())){
			//removed trailing +" " because it was causing indexOf return invalid value
			//Unknown side effects
			obj=FacesUtil.get(obj.toString());			
		}
			encoder.writeObject( obj );
		encoder.close();
		return new String(baut.toByteArray());
	}
 
	private static Object decode(String str){
		ByteArrayInputStream bais=new ByteArrayInputStream(str.getBytes());
		XMLDecoder decoder=new XMLDecoder(bais);
		return decoder.readObject();
	}
 
	public static Object[] params(String str){
		// (?<=</java>)\s*(?=<?)
		String[] obj=str.split("(?<=</java>)\\s*(?=<?)");
		Object[] results=new Object[obj.length];
		for(int i=0;i<obj.length;i++){
			results[i]=decode(obj[i]);
		}
		return results;
	}
 
 
	@SuppressWarnings("unchecked")
	public static Object call(Object owningObject, String qualifiedClassname, String methodName, java.lang.Object... methodArguments) {
		if (null == methodName || methodName.equals("")) {
			throw new IllegalArgumentException("Method name can't be null or empty");
		}
		if (null == methodArguments) {
			methodArguments = new Object[0];
		}
 
		//Check for aliases 
		if(qualifiedClassname.indexOf("@")>-1){
			String subpackage=qualifiedClassname;
			String originalClass=qualifiedClassname;
			//Split at the dot
			boolean isPackageAllias=false;
			String[] sp=subpackage.split("\\.");	
			if(sp.length>1){
				subpackage=sp[0]+".*";
				isPackageAllias=true;
			}
			if(alliasMap.containsKey(subpackage)){
				String value = alliasMap.get(subpackage);
				if(isPackageAllias){
					qualifiedClassname=subpackage.replace(sp[0], value);
					qualifiedClassname=qualifiedClassname.replace(".*", originalClass.replace(sp[0],""));
				}else{
					qualifiedClassname=value;
				}
			}else{
				throw new IllegalArgumentException("Allias name '"+qualifiedClassname+"' not found");
			}
		}
		Class clazz;
		try {
			clazz = Class.forName(qualifiedClassname);
			//Find method by methodName,Argument Types
			Class[] argumentTypes=new Class[methodArguments.length];	
 
			for(int i=0;i<methodArguments.length;i++){
				argumentTypes[i]=methodArguments[i].getClass();
				//Check if the passed in method argument is a string and if its represented as unicode char				
				//if it is then convert it into a char and reassign to the original parameter
				//example 1:  \u0022 == "
				//example 2:  \u0027 == '
				// Reason for this functionality is that we can't pass " and ' from within t:call method
				if (argumentTypes[i] == String.class && methodArguments[i].toString().indexOf("\\u") > -1) {
					String arg = methodArguments[i].toString();
					arg = arg.substring(2, arg.length());
					try {
						int outchar = Integer.parseInt(arg, 16);
						if (Character.isDefined(outchar)) {
							methodArguments[i] = String.valueOf((char) outchar);
						}
					} catch (NumberFormatException nfe) {
						// Suppress error and continue assuming this is a regular string
					}
				}
			}
 
			Method methodToInvoke = null;
			try{
				methodToInvoke  = clazz.getMethod(methodName, argumentTypes);
			}catch(NoSuchMethodException nsm){//Find by method name/ argument count
				for (Method method : clazz.getMethods()) {
					if (method.getName().equals(methodName)  && method.getParameterTypes().length == methodArguments.length) {
						if (null == owningObject) {
							owningObject = clazz.newInstance();
						}
						methodToInvoke=method;
						break;
					}
				}
			}
 
			if(methodToInvoke!=null){								
				return methodToInvoke.invoke(owningObject, methodArguments);
			}else{
				throw new InstantiationException("method not found :" + methodName);	
			}
 
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (InvocationTargetException e) {
			e.printStackTrace();
		} catch (InstantiationException e) {
			e.printStackTrace();
		}
		return null;
	}
 
 
	public static void main(String[] arg) {
		// StringBuffer buff=new StringBuffer();
		// buff.append("Gregs init");
		// Functions.call(java.lang.Class<T>, T, java.lang.String, java.lang.String, java.lang.Object...)
		/*
		 * Functions.call(StringBuffer.class, buff, "java.lang.StringBuffer","append"," Init ");
		 * Functions.call(StringBuffer.class, buff, "java.lang.StringBuffer","append"," greg ");
		 * System.out.println("output="+ buff);
		 */
 
		//#{t:call(null, ".util.DateUtil", "normalizeDate", t:parametize(editRiskActionPlan.riskActionPlan.completionDate,",","java.lang.Object"))}
	//	c(call(null, "util.DateUtil", "normalizeDate", new Date()));
 
		//	#{t:parametize(editRiskActionPlan.riskActionPlan.completionDate,",","java.lang.Object")}
		//parametize((new Date()).toString(),",","java.lang.Object");
		Date a=new Date();
 
		Date b=new Date();
 
		String rawString=param((Date)b, Date.class.toString() );					
		//System.out.println(rawString);
 
		//Replaced=#{t:call("Gregs ' car", 'java.lang.String', 'replace', t:params( parameter ))}
 
		String paramA=param("\\u0027","");
		String paramB=param("\\u0022","");
		String params=paramA+paramB;
		String in="I need to ' have a replaced single quote with double";
		String out=(String)call(in, "java.lang.String", "replace", params(params));
 
		System.out.println(out);
 
 
		/*
		Object[] obj=params(rawString);
		for(Object o:obj){
			System.out.println(o);
		}
		//c(call(null, "@DateUtil", "normalizeDate", obj));
 
		*/
 
	}
 
}

I hope this helps, btw this was copied/pasted from my project so not sure if I missed anything.

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