java用ssh的时候,Gson解析json有外键的时候报错

解析json是用的gson,实体类涉及到三张表三个类,之间的关系是:

C表的一个字段是外键,为A表的主键

C表的另一个字段是外键,为B表的主键

转json的时候报如下异常,该怎么做,请具体一点.

这是多对多的关系吧?

java.lang.UnsupportedOperationException: Attempted to serialize java.lang.Class: org.hibernate.proxy.HibernateProxy. Forgot to register a type adapter?

at com.google.gson.internal.bind.TypeAdapters$1.write(TypeAdapters.java:67)

at com.google.gson.internal.bind.TypeAdapters$1.write(TypeAdapters.java:61)

at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68)

at com.google.gson.internal.bind.ArrayTypeAdapter.write(ArrayTypeAdapter.java:93)

at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68)

at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89)

at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195)

at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68)

at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89)

at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195)

at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68)

at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89)

at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195)

at com.google.gson.internal.bind.ObjectTypeAdapter.write(ObjectTypeAdapter.java:107)

at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrap

解决方案

转换Gson 时要把关联关系解除



1.

public class myExclusionStrategy implements ExclusionStrategy{

private static Logger logger = Logger.getLogger(myExclusionStrategy.class);

String[] jsonKit;

public myExclusionStrategy(String[] jsonKit)

{

this.jsonKit = jsonKit;

}

@Override

public boolean shouldSkipClass(Class<?> arg0) {

// TODO Auto-generated method stub

return false;

}

@Override

public boolean shouldSkipField(FieldAttributes arg0) {

// TODO Auto-generated method stub

if (jsonKit == null)

{

return false;

}

for (String key : jsonKit)

{

if (key.equals(arg0.getName()))

{

return true;

}

}

return false;

}

public static Gson writeJson(HttpServletResponse response, String[] ExList)

{

Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss")

.setExclusionStrategies(new myExclusionStrategy(ExList))

.create();

response.setContentType("application/json;charset=utf-8");

return gson;

}

}

2.

Group group = groupService.get(Group.class,Integer.parseInt(id));

//设置忽略的列,防止外键造成死循环

String[] ExList = {"users","admin"};

Gson gson = new GsonBuilder().setExclusionStrategies(new myExclusionStrategy(ExList)).create();

PrintWriter out = response.getWriter();

out.print(gson.toJson(group));

out.flush();

out.close();