lovinterceptor.java

来自「一个很好的开源项目管理系统源代码」· Java 代码 · 共 85 行

package net.java.workeffort.service.support;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import net.java.workeffort.infrastructure.LabelValueBean;
import net.java.workeffort.infrastructure.cache.ICacheController;
import net.java.workeffort.infrastructure.cache.OsCacheController;
import net.java.workeffort.infrastructure.cache.RefreshRequiredException;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;


/**
 * Interceptor to allow caching of List of values.
 * <p>
 * This will intercept all methods with signature getCached*Lov called on the
 * <code>ListOfValuesService </code>. Methods with other signatures will not be
 * intercepted. So for example an invocation of method getXxxxxLov (note no
 * 'Cached' in name) will *not* be intercepted and will hit the database every
 * single time.
 * @see OsCacheController
 * @author Antony Joseph
 */
public class LovInterceptor implements MethodInterceptor {
    private static final Log logger = LogFactory.getLog(LovInterceptor.class);

    private ICacheController cacheController;

    public Object invoke(MethodInvocation methodInvocation) throws Throwable {
        List lov = null;
        boolean updated = false;

        if (logger.isInfoEnabled()) {
            logger.info("Lov interceptor: method name:" + methodInvocation.getMethod().getName()
                    + ". target object:"
                    + methodInvocation.getThis().getClass().getName());
        }

        // A RefreshRequiredException will occur when no value is found
        // for the key in the cache. If this exception occurs you
        // *absolutely* must either call the putObject() method to put the
        // new object for that key in the cache or call
        // cacheController.cancelUpdate() to let the cache know that you
        // don't intent to set the value for the specific key.
        // see OsCacheController.getObject().
        try {
            lov = (List) cacheController.getObject(methodInvocation.getMethod()
                    .getName());
        }
        catch (RefreshRequiredException rfe) {
            // invoke the method to get the lov
            lov = (List) methodInvocation.proceed();
            cacheController.putObject(methodInvocation.getMethod().getName(),
                    lov);
        }
        finally {
            // If something goes wrong we need to let the cache (oscache)
            // release the lock on the cache entry.
            if (!updated)
                cacheController.cancelUpdate(methodInvocation.getMethod()
                        .getName());
        }

        return lov;
    }

    /**
     * @return Returns the cacheController.
     */
    public ICacheController getCacheController() {
        return cacheController;
    }

    /**
     * @param cacheController The cacheController to set. IOC
     */
    public void setCacheController(ICacheController cacheController) {
        this.cacheController = cacheController;
    }
}