org.springframework.http.converter.HttpMessageNotWritableException:

摘要：在使用Spring+Hibernate搭建RESTful API时，在Hibernate查询出数据实体类使用jackson序列化为json时，返回页面的时候报如下错误：

一：错误信息：

HTTP Status 500 - Could not write JSON: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.HashMap["user"]->com.qdexam.qdky.model.TblUser_$$_javassist_2["handler"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.HashMap["user"]->com.qdexam.qdky.model.TblUser_$$_javassist_2["handler"])

type Exception report

message Could not write JSON: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.HashMap["user"]->com.qdexam.qdky.model.TblUser_$$_javassist_2["handler"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.HashMap["user"]->com.qdexam.qdky.model.TblUser_$$_javassist_2["handler"])

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.HashMap["user"]->com.qdexam.qdky.model.TblUser_$$_javassist_2["handler"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.HashMap["user"]->com.qdexam.qdky.model.TblUser_$$_javassist_2["handler"])
	org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.writeInternal(MappingJackson2HttpMessageConverter.java:196)
	org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:179)
	org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:148)
	org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:90)
	org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:189)
	org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:69)
	org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:746)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:687)
	org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:915)
	org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:811)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:796)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
	org.springframework.orm.hibernate4.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:152)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
root cause

com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.HashMap["user"]->com.qdexam.qdky.model.TblUser_$$_javassist_2["handler"])
	com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:59)
	com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:26)
	com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:503)
	com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:639)
	com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
	com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:491)
	com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:412)
	com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:27)
	com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:114)
	com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:1887)
	org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.writeInternal(MappingJackson2HttpMessageConverter.java:193)
	org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:179)
	org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:148)
	org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:90)
	org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:189)
	org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:69)
	org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:746)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:687)
	org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:915)
	org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:811)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:796)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
	org.springframework.orm.hibernate4.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:152)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.44 logs.

二：解决办法：

关联类里面所有的集合都加入到@JsonIgnoreProperties
这个方法注解是放在类定义上面的,也就是说:
@JsonIgnoreProperties
class A
{

}

如果你定义的类是这样的:

public class A{
	private String description;
	private Boolean enable;
	private Integer createUser;
	private Date createTime;
	private Integer updateUser;
	private Date updateTime;
	private Set operations = new HashSet(0);
	private Set roles = new HashSet(0);
	private Set menus = new HashSet(0);
}

则把下面那句话加进去.
@JsonIgnoreProperties(value={“hibernateLazyInitializer”,”handler”,”operations”,”roles”,”menus”})

其中hibernateLazyInitializer，handler必须添加！

三：这样你再重新访问查询出数据实体类使用jackson序列化为json时就不会再报错了，而是直接返回json格式的数据到浏览器端。