使用hibernate在数据库中存储枚举

Question

我需要使用Hibernate存储一个对象，但是这个对象使用enum。我可以存储，但是当我试图再次检索它时，这个错误失败了:"Studies is not mapped [FROM Studies]"。我在互联网上尝试了很多解决方案，但没有任何效果。我使用MySQL数据库

这是enum:

public enum StudyStatus {
    Created("Created"), Started("Started"), Closed("Closed");
    private final String value;
    StudyStatus(String value){
        this.value = value;
    }

    public static StudyStatus fromValue(int value){
        for (StudyStatus status : values()) {  
            if (status.value.equals(value)) {  
                return status;  
            }  
        }  
        throw new IllegalArgumentException("Invalid status: " + value);  
    }
    public String toValue(){
        return value;
    }
}

这是EnumUserType类

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.Properties;
import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.type.AbstractStandardBasicType;
import org.hibernate.type.IntegerType;
import org.hibernate.type.StringType;
import org.hibernate.usertype.EnhancedUserType;
import org.hibernate.usertype.ParameterizedType;
public abstract class AbstractEnumUserType<E extends Enum<E>, V> implements
    EnhancedUserType, ParameterizedType {
public static int DEAFAULT_SQL_TYPE = Types.INTEGER;
private PreparedStatementSetter psSetter;
private AbstractStandardBasicType<?> basicType;
protected abstract Class<E> getEnumClass();
protected abstract Class<V> getValueClass();
protected abstract E convertEnum(V rawValue);
protected abstract V convertSqlValue(E enumValue);
protected int getSqlType() {
    int sqlType = Types.OTHER;
    switch (getValueClass().getName()) {
    case "java.lang.String":
        sqlType = Types.VARCHAR;
        break;
    case "java.lang.Integer":
        sqlType = Types.INTEGER;
        break;
    default:
        break;
    }
    return sqlType;
}
// ////////////////////////////
@Override
public int[] sqlTypes() {
    return new int[] { getSqlType() };
}
@Override
public Class<?> returnedClass() {
    return getEnumClass();
}
@Override
public boolean equals(Object x, Object y) throws HibernateException {
    return (x == y);
}
@Override
public int hashCode(Object x) throws HibernateException {
    return (x == null) ? 0 : x.hashCode();
}
@Override
public Object nullSafeGet(ResultSet rs, String[] names,
        SessionImplementor session, Object owner)
        throws HibernateException, SQLException {
    Object rawValue = basicType.nullSafeGet(rs, names[0], session, owner);
    Object enumValue = (rawValue == null) ? null
            : convertEnum((V) rawValue);
    return enumValue;
}
@Override
public void nullSafeSet(PreparedStatement st, Object value, int index,
        SessionImplementor session) throws HibernateException, SQLException {
    if (value == null) {
        st.setNull(index, Types.VARCHAR);
    } else {
        psSetter.set(st, convertSqlValue((E) value), index);
    }
}
@Override
public Object deepCopy(Object value) throws HibernateException {
    return value;
}
@Override
public boolean isMutable() {
    return false;
}
@Override
public Serializable disassemble(Object value) throws HibernateException {
    return (Serializable) value;
}
@Override
public Object assemble(Serializable cached, Object owner)
        throws HibernateException {
    return cached;
}
@Override
public Object replace(Object original, Object target, Object owner)
        throws HibernateException {
    return original;
}
@Override
public void setParameterValues(Properties parameters) {
    // Initialize Method
    initBasicType();
    initPreparedStatementSetter();
}
@Override
public String objectToSQLString(Object value) {
    return ''' + ((Enum<?>) value).name() + ''';
}
@Override
public String toXMLString(Object value) {
    return ((Enum<?>) value).name();
}
@Override
public Object fromXMLString(String xmlValue) {
    // TODO
    throw new IllegalAccessError();
    // return Enum.valueOf(, xmlValue);
}
protected void initBasicType() {
    switch (getSqlType()) {
    case Types.VARCHAR:
        basicType = StringType.INSTANCE;
        break;
    case Types.INTEGER:
        basicType = IntegerType.INSTANCE;
        break;
    default:
        break;
    }
}
protected void initPreparedStatementSetter() {
    // TODO
    switch (getSqlType()) {
    case Types.VARCHAR:
        psSetter = new StringPreparedStatementSetter();
        break;
    case Types.INTEGER:
        psSetter = new IntPreparedStatementSetter();
    default:
        break;
    }
}
private static interface PreparedStatementSetter {
    void set(PreparedStatement st, Object value, int index)
            throws SQLException;
}
private static class StringPreparedStatementSetter implements
        PreparedStatementSetter {
    @Override
    public void set(PreparedStatement st, Object value, int index) {
        try {
            st.setString(index, (String) value);
        } catch (SQLException e) {
        }
    }
}
private static class IntPreparedStatementSetter implements
        PreparedStatementSetter {
    @Override
    public void set(PreparedStatement st, Object value, int index) {
        try {
            st.setInt(index, (Integer) value);
        } catch (SQLException e) {
        }
    }
}
}

带有enum

的类

import java.util.ArrayList;
import ateam.capi.common.enums.StudyStatus;
public class Study {
private String id;
private String name;
private StudyStatus status;
private ArrayList<User> pollsters;
private Questionnaire actualQuestionnaire;
public Questionnaire getActualQuestionnaire() {
    return actualQuestionnaire;
}
public void setActualQuestionnaire(Questionnaire actualQuestionnaire) {
    this.actualQuestionnaire = actualQuestionnaire;
}
public String getId() {
    return id;
}
public void setId(String id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public StudyStatus getStatus() {
    return status;
}
public void setStatus(StudyStatus status) {
    this.status = status;
}
public ArrayList<User> getPollsters() {
    return pollsters;
}
public void setPollsters(ArrayList<User> pollsters) {
    this.pollsters = pollsters;
}
}

这是映射Study类的XML

<hibernate-mapping package="ateam.capi.common.beans">
    <class name="Study" table="Studies">
        <id name="id" column="id"></id>
        <property name="name"/>
        <property name="status">
             <type name="ateam.capi.capipersistence.utils.EnumUserType">
                <param name="enumClassName">
                    ateam.capi.common.enums.StudyStatus
                </param>
             </type>
        </property>
    </class>
</hibernate-mapping>

学习DAO类

import java.util.List;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import ateam.capi.capipersistence.utils.HibernateUtil;
import ateam.capi.common.beans.Questionnaire;
import ateam.capi.common.beans.Study;
public class DAO_Study {
private Session session;
private Transaction tx;
public void saveStudy(Study study) throws HibernateException{
    try{
        initOperations();
        session.save(study);
        tx.commit();
    } catch (HibernateException ex){
        handleException(ex);
        throw ex;
    } finally{
        if (session!=null){
            session.close();
        }
    }
}
public void deleteStudy(Study study) throws HibernateException{ 
    try{ 
        initOperations(); 
        this.session.delete(study); 
        this.tx.commit(); 
    } catch (HibernateException ex){ 
        handleException(ex); 
        throw ex; 
    } finally{ 
        if (session!=null){
            session.close();
        } 
    }
}
public List<Study> getStudiesList() throws HibernateException{ 
    List<Study> studiesList = null;  
    try{ 
        initOperations(); 
        String hql = "FROM Studies";
        Query query = session.createQuery(hql);
        studiesList = query.list();
    } catch (HibernateException ex){ 
        handleException(ex); 
        throw ex; 
    } finally{ 
        if (session!=null){
            session.close();
        } 
    } 
    return studiesList; 
}
private void initOperations() throws HibernateException{
    HibernateUtil.createSession();
    this.session = HibernateUtil.getSessionFactory().openSession();
    this.tx = this.session.beginTransaction();
}
private void handleException(HibernateException ex) throws HibernateException{
    this.tx.rollback();
    System.out.println(ex.getStackTrace());
    throw ex;
}
}

我使用Java7与hibernate 4.1.8，我发现其他的解决方案，但不工作在Java7

任何想法?谢谢!

Answer 1

您的查询不应该像from study而不是from studies吗?研究是表格，而不是已定义的实体。