org.apache.struts2.json.JSONException：org.hibernate.LazyInitializationException：无法延迟初始化集合

Question

我从jsp url: "ProductByName"调用自动完成功能。 在控制台中响应时显示

POST http://localhost:8082/Store/SingleProduct 500 (Internal Server Error) 

在jsp中

 $(".name").autocomplete({
                    source: function(request, response) {
                        $.ajax({
                            url: "ProductByName",
                            dataType: "json",
                            data: {
                                str: request.term,
                                maxRows: 5
                            },...

在struts.xml

<action name="ProductByName" class="iland.productdetails.ProductDetailsAction" method="fetchByProductName">
            <result type="json">
                <param name="includeProperties">productList\[\d+\]\.id,
                    productList\[\d+\]\.name,
                    productList\[\d+\]\.description
                </param>
                <param name="excludeNullProperties">true</param>
            </result>
        </action>

我只想获取productList几个属性

行动课

public class ProductDetailsAction extends ActionSupport {

private long id;

private String barCode;//bardoce

private String name;
private String desc;

private long quantity;
private float unitPrice;
private float sellingPrice;
private float totalSellingPrice;
private long clientId;
private ArrayList<BillDetails> BillList;
private Date startDate;
private Date endDate;
private int discountPercentage;
private Timestamp addDate;
private String dataStatus;
private ArrayList<ProductDetailsAction> productList;
private ArrayList<Product> productBillList;
public String fetchByProductName() {
         ProductDetailsBusiness pdb = new ProductDetailsBusiness();
          Map data = pdb.fetchByProductName(getName());
          setProductList((ArrayList) data.get("list"));
          return SUCCESS;
  }
   //other methods and getter and setter
    }   

我正在关注异常

SEVERE: Exception occurred during processing request: org.apache.struts2.json.JSONException: org.apache.struts2.json.JSONException: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: iland.hbm.Client.billDetailses, no session or session was closed
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: iland.hbm.Client.billDetailses, no session or session was closed
    at org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:246)
    at org.apache.struts2.json.JSONWriter.processCustom(JSONWriter.java:178)
    at org.apache.struts2.json.JSONWriter.process(JSONWriter.java:168)
    at org.apache.struts2.json.JSONWriter.value(JSONWriter.java:134)
    at org.apache.struts2.json.JSONWriter.write(JSONWriter.java:102)
    at org.apache.struts2.json.JSONUtil.serialize(JSONUtil.java:116)
    at org.apache.struts2.json.JSONResult.createJSONString(JSONResult.java:197)
    at org.apache.struts2.json.JSONResult.execute(JSONResult.java:171)
    at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:371)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:275)
    at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
    at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:252)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:161)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563)
    at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:744)
Caused by: org.apache.struts2.json.JSONException: org.apache.struts2.json.JSONException: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: iland.hbm.Client.billDetailses, no session or session was closed
    at org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:246)
    at org.apache.struts2.json.JSONWriter.processCustom(JSONWriter.java:178)
    at org.apache.struts2.json.JSONWriter.process(JSONWriter.java:168)
    at org.apache.struts2.json.JSONWriter.value(JSONWriter.java:134)
    at org.apache.struts2.json.JSONWriter.add(JSONWriter.java:390)
    at org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:231)
    ... 71 more
Caused by: org.apache.struts2.json.JSONException: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: iland.hbm.Client.billDetailses, no session or session was closed
    at org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:246)
    at org.apache.struts2.json.JSONWriter.processCustom(JSONWriter.java:178)
    at org.apache.struts2.json.JSONWriter.process(JSONWriter.java:168)
    at org.apache.struts2.json.JSONWriter.value(JSONWriter.java:134)
    at org.apache.struts2.json.JSONWriter.add(JSONWriter.java:390)
    at org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:231)
    ... 76 more
Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: iland.hbm.Client.billDetailses, no session or session was closed
    at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383)
    at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375)
    at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:368)
    at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:111)
    at org.hibernate.collection.PersistentSet.equals(PersistentSet.java:429)
    at java.util.Vector.indexOf(Vector.java:408)
    at java.util.Vector.contains(Vector.java:367)
    at org.apache.struts2.json.JSONWriter.value(JSONWriter.java:117)
    at org.apache.struts2.json.JSONWriter.add(JSONWriter.java:390)
    at org.apache.struts2.json.JSONWriter.bean(JSONWriter.java:231)
    ... 81 more 

编辑： fetchByProductName(getName()); 方法仅包含Jdbc代码。 那么为什么要使用休眠错误器呢？

我正在从数据库中获取日期，也正在控制台上打印。 在成功之前，我给了System.out.println( In action ); 这是正确的aslo打印它不必访问数据库中的数据，然后为什么failed to lazily initialize a collection of XXX如何解决此问题。

编辑

 public class ProductDetailsBusiness {

ProductDetailsAction pda = null;
PreparedStatement ps = null;
ResultSet rs = null, res = null;
Connection con = null;
String status = null;
ArrayList<ProductDetailsAction> ar = null;

public Map fetchByProductName(String name, long cid) {
        System.out.println(" ProductBusiness fetchByProductName()");
        status = "success";
        System.out.println("Name is " + name);

        ar = new ArrayList();
        con = ConnectionFactory.getConnection();

        try {
            String query = "select * from product "
                    + "where status=? and cid=? "
                    + "order by add_date";

            ps = con.prepareStatement(query);
            ps.setString(1, "active");
             ps.setLong(2, cid);
            System.out.println("Before execution");
            res = ps.executeQuery();

            System.out.println("Details are");
            while (res.next()) {
                pda = new ProductDetailsAction();
                long id1 = res.getLong("id");
                String barCode = res.getString("barcode");
                String name1 = res.getString("name");
                String desc = res.getString("description");
                long quntity = res.getLong("quntity");
                float unit_price = res.getLong("unit_price");
                float selling_price = res.getLong("selling_price");
                int discount_percent = res.getInt("discount_percent");
                pda.setId(id1);
                pda.setBarCode(barCode);
                pda.setName(name1);
                pda.setDesc(desc);
                pda.setQuantity(quntity);
                pda.setUnitPrice(unit_price);
                pda.setSellingPrice(selling_price);
                pda.setDiscountPercentage(discount_percent);
                System.out.println("id "+id1+" name "+name1+" "+desc);
                ar.add(pda);
            }

            con.close();
        } catch (SQLException s) {
            status = "failure";
            System.out.println("SQL code does not execute." + s);
        } finally {
            try {
                if (con != null) {
                    con.close();
                }
            } catch (SQLException sqe) {
                status = "failure";
                System.out.println("SQLException " + sqe);
            }
        }
        Map m = new HashMap();
        m.put("status", status);
        m.put("list", ar);
        return m;
    }
      //other methods
    }

还更新了动作课程，请同时查看

Answer 1

LazyInitializationException是此问题的根本原因，当Struts 2 json插件尝试序列化productList对象时，将引发此问题。 根据例外文件

（它）指示访问会话上下文之外的未提取数据。 例如，当关闭会话后访问未初始化的代理或集合时。

这意味着您正在尝试访问billDetailses实体的集合， billDetailses实体以数据库中的Java休眠代理的形式加载。 根据休眠文件

如果在Session范围之外访问未初始化的集合或代理，即当拥有该集合或对该代理的引用的实体处于分离状态时，Hibernate将抛出LazyInitializationException。

因此，这意味着未初始化billDetailses list集合，您可以在完成操作之前使用强制强制初始化

Hibernate.initialize(data) // collection entity

在集合映射上设置FetchType.EAGER也可以解决该问题，但是它将每次添加到billDetailses对象中，因为每次将此对象加载到Java中时，都会强制加载其集合，而从我的角度来看，这就像购买Ferrari并始终在第一时间运行齿轮。

如果您经常收到LazyInitializationException我建议尝试使用OpenSessionInViewFilter ，它可以使休眠会话从请求开始就保持打开状态，直到从应用程序完成响应为止。

Answer 2

JSON的序列化过程由JSON结果控制，JSON结果是您在项目中使用的JSON插件的一部分。 而且您已经知道，要限制序列化程序使用的属性，您应该使用json结果的includeProperties 。 还有一个root属性，您应该检查。 如果未指定，则json结果默认使用值堆栈的top对象。 如果您的操作是模型驱动的，那么模型将覆盖action 。 所以，你在使用的正则表达式includeProperties应用于模型对象，串行这是JSONWriter使用BeanInfo提取bean的属性。 首先，检查这些属性是否存在@JSON批注，如果它具有serialize=false ，则将其跳过，否则将包括在内。 这样，您就可以通过把注解，你不会序列化JSON等属性控制序列化过程@OneToMany性能等，然后includeProperties或excludeProperties如果他们不为空进行检查。 此时，您应该确认，如果您没有与指定模式匹配的属性，那么它们将不会被序列化。 因此，让我们转到LazyInitializationException ，就像我说的那样，如果模型层次结构中曾经有@JSON注释，则应在其中放置serialize=false ，因为默认情况下为true 。

@JSON(serialize=false)
public Object getBillDetailses(){ return billDetailses; }

您在操作类中说了productList ，那么您应该配置结果

<!-- Result config -->
<result type="json">
  <param name="includeProperties">
    ^productList\[\d+\]\.id,
    ^productList\[\d+\]\.name,
    ^productList\[\d+\]\.description
  </param>
  <param name="root">
    #action
  </param>
</result>   

注意， ^代表表达式的开头，因此仅包含动作属性。