SDN Meets Labs - Java Reflection source codes

[Former Member]

These sources will guide you into using Java Reflection. Please also look at following links:

http://java.sun.com/docs/books/tutorial/reflect/

1. [http://java.sun.com/developer/technicalArticles/ALT/Reflection/ | http://java.sun.com/developer/technicalArticles/ALT/Reflection/]
   

This is the project layout i used in the examples

Simple object for testing purposes

DataObject.java

/*

• Created on 2005-04-11

*

• To change the template for this generated file go to

• Window>Preferences>Java>Code Generation>Code and Comments

*/
package pl.com.bcc.demoref;
/**

• @author galczynskim

*

• To change the template for this generated type comment go to

• Window>Preferences>Java>Code Generation>Code and Comments

*/
public class DataObject {
     public String name = "";
     public int age = 0;
     public String SecondName = "";
     protected String protect = "";
     private String privat = "";
}

Servlet for testing the EJB functionality (methods)

RefDemoEjbServlet.java

<span>package pl.com.bcc.demoref;import java.io.IOException;import java.io.PrintWriter;import java.lang.reflect.Method;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class RefDemoEjbServlet extends HttpServlet { protected void doGet(  HttpServletRequest request,  HttpServletResponse response)  throws ServletException, IOException {  PrintWriter wr = response.getWriter();  // should be retrieved from some data store  // eg. session  Object o = null;  try {   javax.naming.Context ctx = new javax.naming.InitialContext();   Object p = ctx.lookup("localejbs/ReflectionTest");   Method createMethod =    p.getClass().getMethod("create", new Class[] {   });   o = createMethod.invoke(p, new Object[] {   });  } catch (Exception e) {   e.printStackTrace(wr);   return;  }  wr.print(   ""    + "</span>

"
+ ""
+ "

");

Class c = o.getClass();
Method mth[] = c.getMethods();
for (int i = 0; i < mth.length; i++) {
if (!mth[i].getName().startsWith("set")) {
continue;
}
String fname = mth[i].getName();
if (request.getParameter(fname) != null) {
try {
if (mth[i].getParameterTypes()[0] == int.class) {
Integer p;
try {
p = new Integer(request.getParameter(fname));
mth[i].invoke(o, new Object[] { p });
} catch (Exception e) {
wr.print(
"

Invalid numeric format, field not set!

");
}
} else {
// assume string
mth[i].invoke(
o,
new Object[] { request.getParameter(fname)});
}
} catch (Exception e) {
// take care here of missed type
// (eg. '321sd' as a number)
e.printStackTrace(wr);
}
}
try {
String xname = mth[i].getName().substring(3);
String mname = "get" + xname;
Method m = o.getClass().getMethod(mname, new Class[] {
});
wr
.print(
xname
+ " :
");
} catch (Exception e) {
;
}

}
wr.print("

" + "");

}

}

Servlet for testing simple funcionality (fields)
RefDemoServlet.java

<span>package pl.com.bcc.demoref;import java.io.IOException;import java.io.PrintWriter;import java.lang.reflect.Field;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class RefDemoServlet extends HttpServlet { protected void doGet(  HttpServletRequest request,  HttpServletResponse response)  throws ServletException, IOException {   // should be retrieved from some data store  // eg. session  Object o = new DataObject();    PrintWriter wr = response.getWriter();    wr.print("" +   "</span>

" +
"

");
          Class c = o.getClass();
          Field fld[] = c.getFields();
          for (int i=0; i<fld.length; i++) {
               String fname = fld[i].getName();
               if (request.getParameter(fname) != null) {
                    try {
                         if (fld[i].getType() == int.class) {
                              fld[i].setInt(o,(new Integer(request.getParameter(fname)).intValue()));
                         } else {
                              // assume string
                              fld[i].set(o, request.getParameter(fname));
                         }
                    } catch (Exception e ){
                         // take care here of missed type
                         // (eg. '321sd' as a number)
                         e.printStackTrace(wr);
                    }
               }
               try {
                    wr.print(fld[i].getName() + " : <input type='text' name='"
                              + fld[i].getName() + "' value='"fld[i].get(o).toString()"'>
");
} catch (Exception e) {
;
}
}

wr.print("

" +
"");

}

}

Following are sources for test EJB.

ReflObjectBean.java

package pl.com.bcc.reflectdemo;
import javax.ejb.EntityBean;
import javax.ejb.EntityContext;
import javax.ejb.RemoveException;
import javax.ejb.CreateException;
/**

• @abstractSchemaName ReflObjectBean

• @cmpVersion 2.x

• @ejbLocal <{pl.com.bcc.reflectdemo.ReflObjectLocal}>

• @ejbLocalHome <{pl.com.bcc.reflectdemo.ReflObjectLocalHome}>

• @ejbPrimaryKey <{java.lang.Object}>

• @hasSimplePK

*/
public abstract class ReflObjectBean implements EntityBean {
     public void ejbLoad() {
     }
     public void ejbStore() {
     }
     public void ejbRemove() throws RemoveException {
     }
     public void ejbActivate() {
     }
     public void ejbPassivate() {
     }
     public void setEntityContext(EntityContext context) {
          myContext = context;
     }
     public void unsetEntityContext() {
          myContext = null;
     }
     private EntityContext myContext;
     /**
     

• Create Method.

      */
     public Object ejbCreate() throws CreateException {
          // TODO : Implement
          return null;
     }
     /**
     

• Post Create Method.

      */
     public void ejbPostCreate() {
          // TODO : Implement
          setAge(0);
          setName("newName");
     }
     public abstract int getAge();
     public abstract void setAge(int age);
     public abstract String getName();
     public abstract void setName(String name);
}

ReflObjectLocal.java

package pl.com.bcc.reflectdemo;
import javax.ejb.EJBLocalObject;
public interface ReflObjectLocal extends EJBLocalObject {
     /**
     

• Business Method.

      */
     public int getAge();
     /**
     

• Business Method.

      */
     public void setAge(int age);
     /**
     

• Business Method.

      */
     public String getName();
     /**
     

• Business Method.

      */
     public void setName(String name);
}

ReflObjectLocalHome.java

package pl.com.bcc.reflectdemo;
import javax.ejb.EJBLocalHome;
import javax.ejb.FinderException;
import javax.ejb.CreateException;
public interface ReflObjectLocalHome extends EJBLocalHome {
     /**
     

• Find Method.

      */
     public ReflObjectLocal findByPrimaryKey(Object primKey)
          throws FinderException;
     /**
     

• Create Method.

      */
     public ReflObjectLocal create() throws CreateException;
     /**
     

• Find Method.

      */
     public ReflObjectLocal findMethod(int arg1) throws FinderException;
}
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