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Jetty example source code file (Injection.java)

This example Jetty source code file (Injection.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Jetty tags/keywords

class, class, field, field, illegalstateexception, initialcontext, injection, member, method, naming, nosuchfieldexception, object, object, reflection, string, string

The Jetty Injection.java source code

//========================================================================
//$Id: Injection.java 1540 2007-01-19 12:24:10Z janb $
//Copyright 2006 Mort Bay Consulting Pty. Ltd.
//------------------------------------------------------------------------
//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.mortbay.jetty.plus.annotation;

import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;



import javax.naming.InitialContext;
import javax.naming.NamingException;

import org.mortbay.log.Log;
import org.mortbay.util.IntrospectionUtil;

/**
 * Injection
 *
 * Represents the injection of a resource into a target (method or field).
 * The injection is performed by doing an ENC lookup using the jndi
 * name provided, and setting the object obtained on the target.
 *
 */
public class Injection
{
    private Class _targetClass;
    private String _jndiName;
    private String _mappingName;
    private Member _target;
    
    
    public Injection ()
    {}
    

    /**
     * @return the _className
     */
    public Class getTargetClass()
    {
        return _targetClass;
    }


    /**
     * @param name the _className to set
     */
    public void setTargetClass(Class clazz)
    {
        _targetClass = clazz;
    }
    
    /**
     * @return the jndiName
     */
    public String getJndiName()
    {
        return _jndiName;
    }
    /**
     * @param jndiName the jndiName to set
     */
    public void setJndiName(String jndiName)
    {
        this._jndiName = jndiName;
    }
    /**
     * @return the mappingName
     */
    public String getMappingName()
    {
        return _mappingName;
    }
    /**
     * @param mappingName the mappingName to set
     */
    public void setMappingName(String mappingName)
    {
        this._mappingName = mappingName;
    }
    
    /**
     * @return the target
     */
    public Member getTarget()
    {
        return _target;
    }
    
    /**
     * @param target the target to set
     */
    public void setTarget(Member target)
    {
        this._target = target;
    }

    //TODO: define an equals method
    
    public void setTarget (Class clazz, String targetName, Class targetType)
    {
        //first look for a javabeans style setter matching the targetName
        String setter = "set"+targetName.substring(0,1).toUpperCase()+targetName.substring(1);
        try
        {
            Log.debug("Looking for method for setter: "+setter+" with arg "+targetType);
            _target = IntrospectionUtil.findMethod(clazz, setter, new Class[] {targetType}, true, false); 
            _targetClass = clazz;
        }
        catch (NoSuchMethodException me)
        {
            //try as a field
            try
            {
                _target = IntrospectionUtil.findField(clazz, targetName, targetType, true, false);
                _targetClass = clazz;
            }
            catch (NoSuchFieldException fe)
            {
                throw new IllegalArgumentException("No such field or method "+targetName+" on class "+_targetClass);
            }
        }
    }

    
    /**
     * Inject a value for a Resource from JNDI into an object
     * @param injectable
     * @throws Exception
     */
    public void inject (Object injectable)
    {
        Member theTarget = getTarget(); 
        if (theTarget instanceof Field)
        {
            injectField((Field)theTarget, injectable);
        }
        else if (theTarget instanceof Method)
        {
            injectMethod((Method)theTarget, injectable);
        }
    }

    
    /**
     * The Resource must already exist in the ENC of this webapp.
     * @return
     * @throws Exception
     */
    public Object lookupInjectedValue ()
    throws NamingException
    {
        InitialContext context = new InitialContext();
        return context.lookup("java:comp/env/"+getJndiName());
    }
    
    

    /**
     * Inject value from jndi into a field of an instance
     * @param field
     * @param injectable
     */
    public void injectField (Field field, Object injectable)
    {           
        try
        {
            //validateInjection(field, injectable);
            boolean accessibility = field.isAccessible();
            field.setAccessible(true);
            field.set(injectable, lookupInjectedValue());
            field.setAccessible(accessibility);
        }
        catch (Exception e)
        {
            throw new IllegalStateException(e);
        }
    }
    
    /**
     * Inject value from jndi into a setter method of an instance
     * @param method
     * @param injectable
     */
    public void injectMethod (Method method, Object injectable)
    {
        //validateInjection(method, injectable);
        try
        {
            boolean accessibility = method.isAccessible();
            method.setAccessible(true);
            method.invoke(injectable, new Object[] {lookupInjectedValue()});
            method.setAccessible(accessibility);
        }
        catch (Exception e)
        {
            throw new IllegalStateException(e);
        }
    }
    
  

    
    private void validateInjection (Method method, Object injectable)
    throws NoSuchMethodException
    {
        if ((injectable==null) || (method==null))
            return;
        //check the injection target actually has a matching method
        //TODO: think about this, they have to be assignable
        injectable.getClass().getMethod(method.getName(), method.getParameterTypes());    
    }
    
    private void validateInjection (Field field, Object injectable) 
    throws NoSuchFieldException
    {
        if ((field==null) || (injectable==null))
            return;

        Field f = injectable.getClass().getField(field.getName());
        if (!f.getType().isAssignableFrom(field.getType()))
            throw new NoSuchFieldException("Mismatching type of field: "+f.getType().getName()+" v "+field.getType().getName());
    }   
}

Other Jetty examples (source code examples)

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