Illegal attempt to map a non collection as a @OneToMany,@ManyToMany or@Collect

问题描述

三个实体类Questions、survey和results。questions和Survey是多对多的关系，results是中间表。Questions类如下：package com.bean;import java.util.HashSet;import java.util.Set;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToMany;import javax.persistence.ManyToOne;@Entitypublic class Questions {private int q_id;//问题主键IDprivate Set<Survey> survey=new HashSet<Survey>();//外键，属于哪一个问卷private QuestionType q_type;//问题类型private AnswerSheet as;//答卷表private String q_head;//问题题目private String q_body;//问题主体private String q_key;//预留字段，如果是网上答卷，则是答案private String q_remarks;// 预留字段，备注private int q_number;//选项个数@Id@GeneratedValue public int getQ_id() {return q_id;}public void setQ_id(int q_id) {this.q_id = q_id;}@ManyToMany(mappedBy="question")public Set<Survey> getSurvey() {return survey;}public void setSurvey(Set<Survey> survey) {this.survey = survey;}public String getQ_head() {return q_head;}public void setQ_head(String q_head) {this.q_head = q_head;}public String getQ_body() {return q_body;}public void setQ_body(String q_body) {this.q_body = q_body;}public String getQ_key() {return q_key;}public void setQ_key(String q_key) {this.q_key = q_key;}public String getQ_remarks() {return q_remarks;}public void setQ_remarks(String q_remarks) {this.q_remarks = q_remarks;}@ManyToOne(cascade=CascadeType.ALL)@JoinColumn (name="qt_id")public QuestionType getQ_type() {return q_type;}public void setQ_type(QuestionType q_type) {this.q_type = q_type;}@ManyToOne@JoinColumn(name="as_id")public AnswerSheet getAs() {return as;}public void setAs(AnswerSheet as) {this.as = as;}@Column(nullable=true)public int getQ_number() {return q_number;}public void setQ_number(int q_number) {this.q_number = q_number;}}Survey类:package com.bean;import java.util.Date;import java.util.HashSet;import java.util.Set;import javax.persistence.CascadeType;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.JoinTable;import javax.persistence.ManyToMany;import javax.persistence.ManyToOne;import javax.persistence.OneToOne;//问卷实体：包括各种属性@Entitypublic class Survey {private int s_id;//问卷IDprivate String s_name;//问卷标题private String s_des;//问卷描述或者备注private boolean s_isOpen;//是否开放private SurveyType s_type;//问卷类型private int s_count;//问卷数量限制private Date s_createTime;//问卷创建时间private Date s_publishTime;//问卷发布时间private Date s_deadline;//问卷截止提交日期private String s_password;//问卷访问密码private String s_isGrade;//问卷是否是打分问卷private AnswerSheet as;//对应答卷private Results results;//对应结果表private Set<Questions> question= new HashSet<Questions>();//private User s_author;//问卷创建者@Id@GeneratedValuepublic int getS_id() {return s_id;}public void setS_id(int s_id) {this.s_id = s_id;}public String getS_name() {return s_name;}public void setS_name(String s_name) {this.s_name = s_name;}public String getS_des() {return s_des;}public void setS_des(String s_des) {this.s_des = s_des;}public boolean isS_isOpen() {return s_isOpen;}public void setS_isOpen(boolean s_isOpen) {this.s_isOpen = s_isOpen;}@ManyToOne@JoinColumn (name="st_id")public SurveyType getS_type() {return s_type;}public void setS_type(SurveyType s_type) {this.s_type = s_type;}public int getS_count() {return s_count;}public void setS_count(int s_count) {this.s_count = s_count;}public Date getS_createTime() {return s_createTime;}public void setS_createTime(Date s_createTime) {this.s_createTime = s_createTime;}public Date getS_publishTime() {return s_publishTime;}public void setS_publishTime(Date s_publishTime) {this.s_publishTime = s_publishTime;}public Date getS_deadline() {return s_deadline;}public void setS_deadline(Date s_deadline) {this.s_deadline = s_deadline;}public String getS_password() {return s_password;}public void setS_password(String s_password) {this.s_password = s_password;}@OneToOne(cascade = CascadeType.ALL,mappedBy="survey")//一对一双向关联public AnswerSheet getAs() {return as;}public void setAs(AnswerSheet as) {this.as = as;}@ManyToMany@JoinTable(name="results",joinColumns={@JoinColumn(name="s_id")},inverseJoinColumns={@JoinColumn(name="q_id")})public Set<Questions> getQuestion() {return question;}public void setQuestion(Set<Questions> question) {this.question = question;}@OneToOne(cascade = CascadeType.ALL,mappedBy="survey")//一对一双向关联public Results getResults() {return results;}public void setResults(Results results) {this.results = results;}public String getS_isGrade() {return s_isGrade;}public void setS_isGrade(String s_isGrade) {this.s_isGrade = s_isGrade;}}results:package com.bean;import java.util.Date;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.OneToMany;import javax.persistence.Table;@Entity@Table(name="results")public class Results {private int r_id;//统计结果表IDprivate Questions questions ;//对应问题题目，外键private Survey survey;//对应问卷，外键private Date r_creatDate;//统计结果表产生时间private int[] r_answerCount;//统计各种答案的数目@Id@GeneratedValuepublic int getR_id() {return r_id;}public void setR_id(int r_id) {this.r_id = r_id;}@OneToMany@JoinColumn(name="q_id")public Questions getQuestions() {return questions;}public void setQuestions(Questions questions) {this.questions = questions;}@OneToMany@JoinColumn (name="s_id")public Survey getSurvey() {return survey;}public void setSurvey(Survey survey) {this.survey = survey;}public Date getR_creatDate() {return r_creatDate;}public void setR_creatDate(Date r_creatDate) {this.r_creatDate = r_creatDate;}public int[] getR_answerCount() {return r_answerCount;}public void setR_answerCount(int[] r_answerCount) {this.r_answerCount = r_answerCount;}}出错信息：org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: com.bean.Results.questionsat org.hibernate.cfg.annotations.CollectionBinder.getCollectionBinder(CollectionBinder.java:266)at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1448)at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:754)at org.hibernate.cfg.AnnotationConfiguration.processArtifactsOfType(AnnotationConfiguration.java:546)at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:291)at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1333)at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867)at com.bean.SurveyTest.BeforeClass(SurveyTest.java:17)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)at java.lang.reflect.Method.invoke(Method.java:597)at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)at org.junit.runners.ParentRunner.run(ParentRunner.java:236)at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)java.lang.NullPointerExceptionat com.bean.SurveyTest.afterClass(SurveyTest.java:87)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)at java.lang.reflect.Method.invoke(Method.java:597)at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:37)at org.junit.runners.ParentRunner.run(ParentRunner.java:236)at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)大侠们，请赶快来看看吧！

解决方案

package com.bean;import java.util.Date;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.OneToMany;import javax.persistence.Table;@Entity@Table(name="results")public class Results {private int r_id;//统计结果表IDprivate Set<Questions> questions = new HashSet<Questions> ;//对应问题题目，外键private Survey survey;//对应问卷，外键private Date r_creatDate;//统计结果表产生时间private int[] r_answerCount;//统计各种答案的数目@Id@GeneratedValuepublic int getR_id() {return r_id;}public void setR_id(int r_id) {this.r_id = r_id;}@OneToMany@JoinColumn(name="q_id")public Set<Questions> getQuestions() {return questions;}public void setQuestions(Set<Questions> questions) {this.questions = questions;}@OneToMany@JoinColumn (name="s_id")public Survey getSurvey() {return survey;}public void setSurvey(Survey survey) {this.survey = survey;}public Date getR_creatDate() {return r_creatDate;}public void setR_creatDate(Date r_creatDate) {this.r_creatDate = r_creatDate;}public int[] getR_answerCount() {return r_answerCount;}public void setR_answerCount(int[] r_answerCount) {this.r_answerCount = r_answerCount;}}