Hibernate：无法初始化代理 – 没有Session（通过引用链……）

注意：在任何人抱怨这是重复之前，请务必仔细阅读内容而不用标题来判断。 另外，请务必仔细阅读您的参考问题和答案，看看它是否重复。 根据我的经验，这个问题可以在不同的环境下发生。 举个例子，在jsp使用下面代码的人的答案会有所不同，因为使用Spring会有所不同，而且对于那些DB很小而且负载很好的人会有所不同。 不，我的情况不是他们中的任何一个。

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我正在使用Hibernate和Jersey编写REST api。 请看下面的代码。

VerificationCodeJSONService.java – JSON服务类

 @Path("/verificaion_code") public class VerificationCodeJSONService { @GET @Path("/getAllVerificationCodes") @Produces(MediaType.APPLICATION_JSON) public List getAllVerificationCodes() { VerificationCodeService verificationCodeService=new VerificationCodeService(); List list = verificationCodeService.getAllVerificationCodes(); return list; } } 

VerificationCodeService.java – 服务层

 public class VerificationCodeService { private static VerificationCodeDAOInterface verificationCodeDAOInterface; public VerificationCodeService() { verificationCodeDAOInterface = new VerificationCodeDAOImpl(); } public List getAllVerificationCodes() { Session session = verificationCodeDAOInterface.openCurrentSession(); Transaction transaction = null; List verificaionCodes = new ArrayList(); try { transaction = verificationCodeDAOInterface.openTransaction(session); verificaionCodes = verificationCodeDAOInterface.getAllVerificationCodes(session); transaction.commit(); } catch (Exception ex) { ex.printStackTrace(); } finally { session.close(); } return verificaionCodes; } } 

VerificationCodeDAOImpl.java – 数据库层

 public class VerificationCodeDAOImpl implements VerificationCodeDAOInterface{ private static final SessionFactoryBuilder sessionFactoryBuilder = SessionFactoryBuilder.getInstance(); @Override public List getAllVerificationCodes(Session session) { List verificaionCodes=(List)session.createQuery("from VerificaionCode").list(); return verificaionCodes; } } 

VerificationCode.java – DAO层

 public class VerificaionCode implements java.io.Serializable { private Integer idverificaionCode; private Patient patient; private String code; private Date dateCreated; private Date lastUpdated; public VerificaionCode() { } public VerificaionCode(Patient patient, String code, Date lastUpdated) { this.patient = patient; this.code = code; this.lastUpdated = lastUpdated; } public VerificaionCode(Patient patient, String code, Date dateCreated, Date lastUpdated) { this.patient = patient; this.code = code; this.dateCreated = dateCreated; this.lastUpdated = lastUpdated; } public Integer getIdverificaionCode() { return this.idverificaionCode; } public void setIdverificaionCode(Integer idverificaionCode) { this.idverificaionCode = idverificaionCode; } public Patient getPatient() { return this.patient; } public void setPatient(Patient patient) { this.patient = patient; } public String getCode() { return this.code; } public void setCode(String code) { this.code = code; } public Date getDateCreated() { return this.dateCreated; } public void setDateCreated(Date dateCreated) { this.dateCreated = dateCreated; } public Date getLastUpdated() { return this.lastUpdated; } public void setLastUpdated(Date lastUpdated) { this.lastUpdated = lastUpdated; } } 

Patient.java – DAO层

 public class Patient implements java.io.Serializable { private Integer idpatient; private DiabetesType diabetesType; private Language language; private String customId; private String diabetesOther; private String firstName; private String lastName; private String email; private Date dob; private String parentEmail; private String gender; private Date diagnosedDate; private Double height; private Double weight; private String heightUnit; private String weightUnit; private String theme; private String userName; private String password; private Date dateCreated; private Date lastUpdated; public Patient() { } public Patient(DiabetesType diabetesType, Language language, String customId, String firstName, String email, Date dob, String gender, String theme, String userName, String password, Date lastUpdated) { this.diabetesType = diabetesType; this.language = language; this.customId = customId; this.firstName = firstName; this.email = email; this.dob = dob; this.gender = gender; this.theme = theme; this.userName = userName; this.password = password; this.lastUpdated = lastUpdated; } public Integer getIdpatient() { return this.idpatient; } public void setIdpatient(Integer idpatient) { this.idpatient = idpatient; } public DiabetesType getDiabetesType() { return this.diabetesType; } public void setDiabetesType(DiabetesType diabetesType) { this.diabetesType = diabetesType; } public Language getLanguage() { return this.language; } public void setLanguage(Language language) { this.language = language; } public String getCustomId() { return this.customId; } public void setCustomId(String customId) { this.customId = customId; } public String getDiabetesOther() { return this.diabetesOther; } public void setDiabetesOther(String diabetesOther) { this.diabetesOther = diabetesOther; } public String getFirstName() { return this.firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return this.lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getEmail() { return this.email; } public void setEmail(String email) { this.email = email; } public Date getDob() { return this.dob; } public void setDob(Date dob) { this.dob = dob; } public String getParentEmail() { return this.parentEmail; } public void setParentEmail(String parentEmail) { this.parentEmail = parentEmail; } public String getGender() { return this.gender; } public void setGender(String gender) { this.gender = gender; } public Date getDiagnosedDate() { return this.diagnosedDate; } public void setDiagnosedDate(Date diagnosedDate) { this.diagnosedDate = diagnosedDate; } public Double getHeight() { return this.height; } public void setHeight(Double height) { this.height = height; } public Double getWeight() { return this.weight; } public void setWeight(Double weight) { this.weight = weight; } public String getHeightUnit() { return this.heightUnit; } public void setHeightUnit(String heightUnit) { this.heightUnit = heightUnit; } public String getWeightUnit() { return this.weightUnit; } public void setWeightUnit(String weightUnit) { this.weightUnit = weightUnit; } public String getTheme() { return this.theme; } public void setTheme(String theme) { this.theme = theme; } public String getUserName() { return this.userName; } public void setUserName(String userName) { this.userName = userName; } public String getPassword() { return this.password; } public void setPassword(String password) { this.password = password; } public Date getDateCreated() { return this.dateCreated; } public void setDateCreated(Date dateCreated) { this.dateCreated = dateCreated; } public Date getLastUpdated() { return this.lastUpdated; } public void setLastUpdated(Date lastUpdated) { this.lastUpdated = lastUpdated; } } 

下面是我上面的POJO的Hibernate映射文件

VerificaionCode.hbm.xml

Patient.hbm.xml

                                                                     Stores the basic information of the patient     

但是，当我通过http://localhost:8080/example_rest/rest/verificaion_code/getAllVerificationCodes运行此代码时，我收到以下错误。

 could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]->beans.VerificaionCode["patient"]->beans.Patient_$$_jvst40f_7["diabetesType"]) 

如您所见， diabetesType是患者表中的Object （外键），与VerificationCode无关。 我该如何解决这个问题？

请注意，这是一个REST API。 所以我不能像在Web应用程序中那样在JSP中加载它们。

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更新

正如@Kayaman推荐的那样，我通过制作null来进行更新。 请检查以下代码。 我注意到verificaionCodes.get(i).getPatient().set...(null)产生与上面相同的错误，所以我尝试下面开始正常工作。

VerificationCodeService.java

 public List getAllVerificationCodes() { Session session = verificationCodeDAOInterface.openCurrentSession(); Transaction transaction = null; List verificaionCodes = new ArrayList(); try { transaction = verificationCodeDAOInterface.openTransaction(session); verificaionCodes = verificationCodeDAOInterface.getAllVerificationCodes(session); transaction.commit(); } catch (Exception ex) { ex.printStackTrace(); } finally { session.close(); for(int i=0;i<verificaionCodes.size();i++) { Patient p = new Patient(); System.out.println(verificaionCodes.get(i).getPatient().getIdpatient()); Integer idpatient = verificaionCodes.get(i).getPatient().getIdpatient(); p.setIdpatient(idpatient); verificaionCodes.get(i).setPatient(p); } } return verificaionCodes; }