Mybatis懒加载的实现

public class JavassistProxyFactory implements org.apache.ibatis.executor.loader.ProxyFactory {

 
 /**
 * 接口实现
 * @param target 目标结果对象
 * @param lazyLoader 延迟加载对象
 * @param configuration 配置
 * @param objectFactory 对象工厂
 * @param constructorArgTypes 构造参数类型
 * @param constructorArgs 构造参数值
 * @return
 */
 @Override
 public Object createProxy(Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
 return EnhancedResultObjectProxyImpl.createProxy(target, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
 }

 //省略...
 
 /**
 * 代理对象实现，核心逻辑执行
 */
 private static class EnhancedResultObjectProxyImpl implements MethodHandler {
 
 /**
 * 创建代理对象
 * @param type
 * @param callback
 * @param constructorArgTypes
 * @param constructorArgs
 * @return
 */
 static Object crateProxy(Class<?> type, MethodHandler callback, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {

 ProxyFactory enhancer = new ProxyFactory();
 enhancer.setSuperclass(type);

 try {
  //通过获取对象方法，判断是否存在该方法
  type.getDeclaredMethod(WRITE_REPLACE_METHOD);
  // ObjectOutputStream will call writeReplace of objects returned by writeReplace
  if (log.isDebugEnabled()) {
  log.debug(WRITE_REPLACE_METHOD + " method was found on bean " + type + ", make sure it returns this");
  }
 } catch (NoSuchMethodException e) {
  //没找到该方法，实现接口
  enhancer.setInterfaces(new Class[]{WriteReplaceInterface.class});
 } catch (SecurityException e) {
  // nothing to do here
 }

 Object enhanced;
 Class<?>[] typesArray = constructorArgTypes.toArray(new Class[constructorArgTypes.size()]);
 Object[] valuesArray = constructorAr<b>本文来源gao@!dai!ma.com搞$$代^@码5网@</b>gs.toArray(new Object[constructorArgs.size()]);
 try {
  //创建新的代理对象
  enhanced = enhancer.create(typesArray, valuesArray);
 } catch (Exception e) {
  throw new ExecutorException(&quot;Error creating lazy proxy. Cause: &quot; + e, e);
 }
 //设置代理执行器
 ((Proxy) enhanced).setHandler(callback);
 return enhanced;
 }
 
 
  /**
  * 代理对象执行
  * @param enhanced 原对象
  * @param method 原对象方法
  * @param methodProxy 代理方法
  * @param args 方法参数
  * @return
  * @throws Throwable
  */
 @Override
 public Object invoke(Object enhanced, Method method, Method methodProxy, Object[] args) throws Throwable {
  final String methodName = method.getName();
  try {
  synchronized (lazyLoader) {
   if (WRITE_REPLACE_METHOD.equals(methodName)) { 
   //忽略暂未找到具体作用
   Object original;
   if (constructorArgTypes.isEmpty()) {
    original = objectFactory.create(type);
   } else {
    original = objectFactory.create(type, constructorArgTypes, constructorArgs);
   }
   PropertyCopier.copyBeanProperties(type, enhanced, original);
   if (lazyLoader.size() &gt; 0) {
    return new JavassistSerialStateHolder(original, lazyLoader.getProperties(), objectFactory, constructorArgTypes, constructorArgs);
   } else {
    return original;
   }
   } else {
    //延迟加载数量大于0
   if (lazyLoader.size() &gt; 0 &amp;&amp; !FINALIZE_METHOD.equals(methodName)) {
    //aggressive 一次加载性所有需要要延迟加载属性或者包含触发延迟加载方法
    if (aggressive || lazyLoadTriggerMethods.contains(methodName)) {
    log.debug(&quot;==&gt; laze lod trigger method:&quot; + methodName + &quot;,proxy method:&quot; + methodProxy.getName() + &quot; class:&quot; + enhanced.getClass());
    //一次全部加载
    lazyLoader.loadAll();
    } else if (PropertyNamer.isSetter(methodName)) {
    //判断是否为set方法，set方法不需要延迟加载
    final String property = PropertyNamer.methodToProperty(methodName);
    lazyLoader.remove(property);
    } else if (PropertyNamer.isGetter(methodName)) {
    final String property = PropertyNamer.methodToProperty(methodName);
    if (lazyLoader.hasLoader(property)) {
     //延迟加载单个属性
     lazyLoader.load(property);
     log.debug(&quot;load one :&quot; + methodName);
    }
    }
   }
   }
  }
  return methodProxy.invoke(enhanced, args);
  } catch (Throwable t) {
  throw ExceptionUtil.unwrapThrowable(t);
  }
 }
 }