GSON 报错HibernateProxy. Forgot to register a type adapter? 的解决办法

使用Gson转换hibernate对象遇到一个问题，当对象的Lazy加载的，就会出现上面的错误。处理方式摘抄自网上，留存一份以后自己看。

网上找到的解决办法,首先自定义一个类继承TypeAdapter:

 package cn.xjy.finance.loanapply.utils ;

 import java.io.IOException ;
 import org.hibernate.Hibernate ;
 import org.hibernate.proxy.HibernateProxy ;
 import com.google.gson.Gson ;
 import com.google.gson.TypeAdapter ;
 import com.google.gson.TypeAdapterFactory ;
 import com.google.gson.reflect.TypeToken ;
 import com.google.gson.stream.JsonReader ;
 import com.google.gson.stream.JsonWriter ;

 /**
  * This TypeAdapter unproxies Hibernate proxied objects, and serializes them
  * through the registered (or default) TypeAdapter of the base class.
  */
 public class HibernateProxyTypeAdapter extends TypeAdapter<HibernateProxy> {

     public static final TypeAdapterFactory    FACTORY    = new TypeAdapterFactory() {
         @Override
         @SuppressWarnings("unchecked")
         public <T> TypeAdapter<T> create(Gson gson,
                 TypeToken<T> type) {
             return (HibernateProxy.class
                     .isAssignableFrom(type
                             .getRawType()) ? (TypeAdapter<T>) new HibernateProxyTypeAdapter(
                     gson) : null) ;
         }
     } ;

     private final Gson                        context ;

     private HibernateProxyTypeAdapter(Gson context) {
         this.context = context ;
     }

     @Override
     public HibernateProxy read(JsonReader in) throws IOException {
         throw new UnsupportedOperationException("Not supported") ;
     }

     @SuppressWarnings({ "rawtypes", "unchecked" })
     @Override
     public void write(JsonWriter out, HibernateProxy value) throws IOException {
         if (value == null) {
             out.nullValue() ;
             return ;
         }
         // Retrieve the original (not proxy) class
         Class<?> baseType = Hibernate.getClass(value) ;
         // Get the TypeAdapter of the original class, to delegate the
         // serialization
         TypeAdapter delegate = context.getAdapter(TypeToken.get(baseType)) ;
         // Get a filled instance of the original class
         Object unproxiedValue = ((HibernateProxy) value).getHibernateLazyInitializer()
                 .getImplementation() ;
         // Serialize the value
         delegate.write(out, unproxiedValue) ;
     }
 }

然后初始化gson对象的方式:

 Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd")
                                                     .registerTypeAdapterFactory(
                                                     HibernateProxyTypeAdapter.FACTORY).create() ;                

这样就解决了,出现这个错误的主要原因是,hibernate采取懒加载的方式查询数据库,也就是只有用到了才去查真正的数据,用不到的话只是返回一个代理对象,gson识别不了代理对象,所以没法转换.