cacheinterceptor.java

Java/J2EE框架Jdon-Framework系统的Sample

/**
 * Copyright 2005 Jdon.com
 * 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 com.jdon.aop.interceptor;

import java.lang.reflect.*;
import org.aopalliance.intercept.*;
import com.jdon.controller.model.*;
import com.jdon.model.*;
import com.jdon.util.*;

/**
 * 缓存拦截器
 * 所有拦截器是存放在PicoContainer中，
 *
 * Cache Interceptor
 * all Interceptors are added in picoContainer
 * @see  AopInterceptorRegistry.java
 *
 * <p></p>
 * @author banq
 * @version 1.0
 */
public class CacheInterceptor implements MethodInterceptor {
  private final static String module = CacheInterceptor.class.getName();

  private ModelManager modelManager;
  public String match_MethodName = "get";

  public CacheInterceptor(ModelManager modelManager){
     this.modelManager = modelManager;
  }

  /**
   * Cache实现方法
   * 1.检查返回类型是否为Model
   * 2.检查方法名中是否有get；
   * 3.实现Model 缓存。
   *
   *  拦截成功，就直接返回， 该拦截器适合是倒数第一，紧靠数据源
   *
   * @param invocation MethodInvocation
   * @throws Throwable
   * @return Object
   */
  public Object invoke(MethodInvocation invocation) throws Throwable {
    Method method = invocation.getMethod();
    Debug.logVerbose(" enter cacheInteceptor method:" + method.getName(), module);
    if (!methodMatchsModelGET(method)) {
      Debug.logVerbose(" cacheInteceptor don't action, enter next invocation.proceed()", module);
      return invocation.proceed(); //下一个interceptor
    }

    String dataKey = getArguments(invocation);
    Class modelClass = method.getReturnType();
    ModelKey modelKey = new ModelKey(dataKey, modelClass);
    Model model = modelManager.getCache(modelKey);
    if (model == null){
      model = (Model) invocation.proceed(); //下一个interceptor
      if ( (model != null) && (dataKey != null) && (model.isCacheble())) {
        modelManager.addCache(modelKey, model);
      }
    }
    return model;
  }


  /**
   *  * 1.检查返回类型是否为Model
   * 2.检查方法名中是否有get；
   * @param method Method
   * @return boolean
   */
  private boolean methodMatchsModelGET(Method method) {
    boolean condition = false;
    try {
      String mehtodName = method.getName();
      if (method.getReturnType() == null)return condition; //无返回值，不做缓存
      Class returnClass = method.getReturnType();

      if (returnClass.getSuperclass() == null)return condition; //无返回值，不做缓存

      String returnClassName = returnClass.getSuperclass().getName();
      Debug.logVerbose("returnClassName = " + returnClassName, module);
      if ( (returnClassName.equalsIgnoreCase("com.jdon.controller.model.Model"))
          && (mehtodName.indexOf(match_MethodName) != -1)) {
        condition = true;
      }
    } catch (Exception ex) {
      Debug.logError("Exception error:" + ex, module);
    } catch (Throwable the) {
      Debug.logError("Throwable error:" + the, module);
    }
    return condition;

  }

  /**
   * 组合参数数值为一个字符串
   * 这些参数必须实现toString();
   *
   * @param invocation MethodInvocation
   * @return String
   */
  public String getArguments(MethodInvocation invocation) {
    Object[] args = invocation.getArguments();
    if (args == null) return null;
    StringBuffer buff = new StringBuffer();
    for (int i = 0; i < args.length; i++) {
      buff.append(getArgString(args[i]));
    }
    return buff.toString();
  }

  private String getArgString(Object arg) {
    String res = "";
    try {
      res = arg.toString();
    } catch (Exception ex) {
      Debug.logError(" arg: " + arg.getClass().getName() +
                     " has not implements method: toString() ", module);
    }
    return res;

  }

  public String getMatch_MethodName() {
    return match_MethodName;
  }

  public void setMatch_MethodName(String match_MethodName) {
    this.match_MethodName = match_MethodName;
  }

}