使用Struts 2输出时出现JSON异常错误 [英] JSON exception error while output using Struts 2
本文介绍了使用Struts 2输出时出现JSON异常错误的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
类型异常报告
消息
说明服务器遇到内部错误（），导致无法完成此请求。
例外
org.apache.struts2.json.JSONException：org.apache.struts2.json.JSONException：org.apache.struts2.json.JSONException：org.hibernate .LazyInitializationException：未能延迟初始化角色集合：com.ProductDetails.ISN，没有会话或会话已关闭
org.apache.struts2.json.JSONWriter.bean（JSONWriter.java:209）
org.apache.struts2.json.JSONWriter.process（JSONWriter.java:140）
org.apache.struts2.json.JSONWriter.value（JSONWriter.java:216）
org.apache.struts2。 json.JSONWriter.write（JSONWriter.java:94）
org.apache.struts2.json.JSONUtil.serialize（JSONUtil.java:115）
org.apache.struts2.json.JSONResult.createJSONString（ JSONResult.java:200）
org.apache.struts2.json.JSONResult.execute（JSONResult.java:172）
com.opensymphony.xwork2.DefaultActionInvocation.executeResult（DefaultActionInvocation.java:361）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocatio n.java:265）
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept（DefaultWorkflowInterceptor.java:163）
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:87）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept（ValidationInterceptor.java:249）
org.apache。 struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept（AnnotationValidationInterceptor.java:68）
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:87）
com.opensymphony.xwork2.DefaultActionInvocation。 invoke（DefaultActionInvocation.java:236）
com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept（ConversionErrorInterceptor.java:122）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvoca tion.java:236）
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept（ParametersInterceptor.java:195）
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:87）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept（ParametersInterceptor.java:195）
com.opensymphony。 xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:87）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept（ StaticParametersInterceptor.java:148）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
org.apache.struts2.interceptor.CheckboxInterceptor.intercept（CheckboxInterceptor.java:93）
com.opensymphony .xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
org.apache.struts2.interceptor.FileUploadInterceptor.intercept（FileUploadInterceptor.java:235）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation .java：236）
com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept（ModelDrivenInterceptor.java:89）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept（ScopedModelDrivenInterceptor.java:128）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
org.apache.struts2.interceptor .ProfilingActivationInterceptor.intercept（ProfilingActivationInterceptor.java:104）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
org.apache.struts2.interceptor.debugging.DebuggingInterceptor.inter （DebuggingInterceptor.java:267）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept（ChainingInterceptor.java:126）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept（PrepareInterceptor.java:138）
com.opensymphony。 xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:87）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept（ I18nInterceptor.java:148）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
org.apache.struts2.interceptor.ServletConfigInterceptor.intercept（ServletConfigInterceptor.java:164）
com.opensymphony.xwork2.DefaultAct ionInvocation.invoke（DefaultActionInvocation.java:236）
com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept（AliasInterceptor.java:128）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java：
com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept（ExceptionMappingInterceptor.java:176）
com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:236）
org。 apache.struts2.impl.StrutsActionProxy.execute（StrutsActionProxy.java:52）
org.apache.struts2.dispatcher.Dispatcher.serviceAction（Dispatcher.java:468）
org.apache.struts2.dispatcher。
org.springframework.security.web。 FilterChainProxy $ VirtualFilterChain.doFilter（FilterChainProxy.java:366）
org.spr ingframework.security.web.access.intercept.FilterSecurityInterceptor.invoke（FilterSecurityInterceptor.java:109）
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter（FilterSecurityInterceptor.java:83）
org.springframework.security.web.FilterChainProxy $ VirtualFilterChain.doFilter（FilterChainProxy.java:378）
org.springframework.security.web.access.ExceptionTranslationFilter.doFilter（ExceptionTranslationFilter.java:97）
org。 springframework.security.web.FilterChainProxy $ VirtualFilterChain.doFilter（FilterChainProxy.java:378）
org.springframework.security.web.session.SessionManagementFilter.doFilter（SessionManagementFilter.java:100）
org.springframework。 security.web.FilterChainProxy $ VirtualFilterChain.doFilter（FilterChainProxy.java:378）
org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter（AnonymousAuthenticationFilter.java:78）
org.springframework.security。 web.Fi lterChainProxy $ VirtualFilterChain.doFilter（FilterChainProxy.java:378）
org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter（SecurityContextHolderAwareRequestFilter.java:54）
org.springframework.security.web.FilterChainProxy $ VirtualFilterChain.doFilter（FilterChainProxy.java:378）
org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter（RequestCacheAwareFilter.java:35）
org.springframework.security.web.FilterChainProxy $ VirtualFilterChain。 doFilter（FilterChainProxy.java:378）
org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter（AbstractAuthenticationProcessingFilter.java:187）
org.springframework.security.web.FilterChainProxy $ VirtualFilterChain.doFilter（ FilterChainProxy.java:378）
org.springframework.security.web.authentication.logout.LogoutFilter.doFilter（LogoutFilter.java:105）
org.springframework.security.web.FilterChain代理$ VirtualFilterChain.doFilter（FilterChainProxy.java:378）
org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter（SecurityContextPersistenceFilter.java:79）
org.springframework.security.web.FilterChainProxy $ VirtualFilterChain.doFilter（FilterChainProxy.java:378）
org.springframework.security.web.FilterChainProxy.doFilter（FilterChainProxy.java:167）
org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate（DelegatingFilterProxy。 java：237）
org.springframework.web.filter.DelegatingFilterProxy.doFilter（DelegatingFilterProxy.java:167）
Book class：
@Id
@GeneratedValue（...）
@ SequenceGenerator（...）
int bookId;
@Column（name =ISN，updatable = false，insertable = false）
字符串ISN;
@ManyToOne
@JoinColumn（name =ISN，referencedColumnName =ISN）
BookDetails bD;
我的JSON操作实现很简单：
私人列表<图书> bookIDLists;
// getter& setter
public String execute（）{
BooksDAO b = new BooksDAO（）;
bookIDLists = b.someSearchMethod;
返回SUCCESS;
getAllBookIDs（）的hibernate实现如下所示：
String string =from Books;
Query query = s.createQuery（string）;
List list = query.list（）;
并且struts.xml文件看起来像这样：
< action name =JSONtestclass =com.JSONTestmethod =execute>
< result type =json/>
< / action>
我测试了方法 getAllBookIDs ，而我从该方法获得正确的输出。但是，当我试图通过JSON获得输出并将其执行到浏览器时，我收到了错误。
有没有什么建议可以解决这个异常？
问题在于，当Hibernate会话关闭时，发生了对JSON的序列化。
实体可能包含为延迟加载映射的属性。它们不会默认加载，例如集合和关联。如果你想加载它们，你应该在会话打开的时候做，比如使用 FetchType.EAGER 或者使用在视图中打开会话实现。就像它已经在完整的Hibernate插件中完成一样。否则，您必须通过 @JSON 注释来控制序列化，并使用 json 结果类型的参数，允许包含和排除JSON结果使用的属性序列化对象。有关详细信息，请参阅 JSON插件。
I am getting the JSON Exception error when I am executing the result into the browser like the following:
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.struts2.json.JSONException: org.apache.struts2.json.JSONException: org.apache.struts2.json.JSONException: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.ProductDetails.ISN, no session or session was closed
org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:209)
org.apache.struts2.json.JSONWriter.process(JSONWriter.java:140)
org.apache.struts2.json.JSONWriter.value(JSONWriter.java:216)
org.apache.struts2.json.JSONWriter.write(JSONWriter.java:94)
org.apache.struts2.json.JSONUtil.serialize(JSONUtil.java:115)
org.apache.struts2.json.JSONResult.createJSONString(JSONResult.java:200)
org.apache.struts2.json.JSONResult.execute(JSONResult.java:172)
com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:361)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:265)
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:163)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:249)
org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:148)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:93)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:128)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
org.apache.struts2.interceptor.ProfilingActivationInterceptor.intercept(ProfilingActivationInterceptor.java:104)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:148)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:128)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236)
org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:468)
org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:76)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:366)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:187)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:167)
org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
Book class:
@Id
@GeneratedValue(...)
@SequenceGenerator(...)
int bookId;
@Column(name = "ISN", updatable = false, insertable = false)
String ISN;
@ManyToOne
@JoinColumn(name = "ISN", referencedColumnName = "ISN")
BookDetails bD;
My JSON action implementation is simple like:
private List<Books> bookIDLists;
// getter & setter
public String execute() {
BooksDAO b = new BooksDAO();
bookIDLists = b.someSearchMethod;
return SUCCESS;
}
And the hibernate implementation of "getAllBookIDs()" is like the following:
String string = "from Books";
Query query = s.createQuery(string);
List list = query.list();
And the struts.xml file looks:
<action name="JSONtest" class="com.JSONTest" method="execute">
<result type="json" />
</action>
I tested the method getAllBookIDs and I am getting the correct output form the method. But when i tried to get the output through JSON and execute it to the browser then I am getting the error.
Is there any suggestion to solve the exception?
解决方案
The problem is that serialization to JSON happened when the Hibernate session is closed.
The entity might contain the properties mapped for lazy loading. They aren't loaded by default, such as collections and associations. If you want to load them you should do it while the session is open, such as use FetchType.EAGER or use Open Session In View implementation. Like it's already done in Full Hibernate Plugin.
Otherwise, you have to control the serialization via @JSON annotation and use json result type with parameters that allows including and excluding properties used by JSON result to serialize the object. More about this you can find in the documentation page for JSON Plugin.
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