hibernate字段映射枚举类型

上一篇介绍了mybatis字段映射枚举类型，这一篇给大家介绍一下hibernate字段怎么去映射枚举类型的（这只是一种参考方式，映射方法还有很多种）。

还是以上篇sku表为例，sku表里一个status_type字段为int类型。(这里是postgresql的脚本)

status_type int4 NULL

Java里面对应生成的枚举类为：

 public enum SkuStatusType implements DbEnum, LocalString {

     PRODUCT(0, false, "masterdata.skuStatus.product"),
     BUYING(1, false, "masterdata.skuStatus.buying"),
     SALE(2, false, "masterdata.skuStatus.sale");

     private int dbConstant;
     private String messageKey;

     private OrderState(int dbConstant, boolean hasBeenDispatched, String messageKey) {
         this.dbConstant = dbConstant;
         this.hasBeenDispatched = hasBeenDispatched;
         this.messageKey = messageKey;
     }

     @Override
     public Integer getConstant() {
         return this.dbConstant;
     }

     @Override
     public String messageKey() {
         return this.messageKey;
     }
 }

接下来是和mybatis不同的地方，所写的工具类不一样，看一下为hibernate写的工具类：

 package com.lcc.core.domain;

 import java.io.Serializable;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Types;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;

 import org.hibernate.HibernateException;
 import org.hibernate.usertype.ParameterizedType;
 import org.hibernate.usertype.UserType;
 import org.hibernate.util.ReflectHelper;

 import com.lcc.api.domain.DbEnum;

 public class DbEnumType implements UserType, ParameterizedType {

     private static final int[] SQL_TYPES = { Types.INTEGER };

     private Class<? super Enum<?>> enumClass;
     private Map<Integer, Object> constantMap = null;

     @Override
     public int[] sqlTypes() {
         return SQL_TYPES;
     }

     @Override
     @SuppressWarnings("rawtypes")
     public Class returnedClass() {
         return enumClass;
     }

     @Override
     public boolean equals(Object x, Object y) {
         if (x == y) {
             return true;
         }
         if (x == null || y == null) {
             return false;
         }
         return x.equals(y);
     }

     @Override
     public int hashCode(Object x) {
         return x.hashCode();
     }

     @Override
     public Object nullSafeGet(ResultSet rs, String[] names, Object owner) throws SQLException {
         Integer value = rs.getInt(names[0]);
         if (rs.wasNull()) {
             return null;
         } else {
             return getEnumConstant(value);
         }
     }

     private Object getEnumConstant(Integer value) {
         if (constantMap == null) {
             Map constantMap = new HashMap<Integer, Object>();

             Object[] enumConstants = enumClass.getEnumConstants();
             for (Object enumC : enumConstants) {
                 constantMap.put(((DbEnum) enumC).getConstant(), enumC);
             }
             this.constantMap = constantMap;
         }
         return constantMap.get(value);
     }

     @Override
     public void nullSafeSet(PreparedStatement st, Object value, int index) throws SQLException {
         if (value == null) {
             st.setNull(index, Types.INTEGER);
         } else {
             DbEnum e = (DbEnum) value;
             st.setInt(index, e.getConstant());
         }
     }

     @Override
     public Object deepCopy(Object value) {
         if (value == null) {
             return null;
         } else {
             return value;
         }
     }

     @Override
     public boolean isMutable() {
         return false;
     }

     @Override
     public Serializable disassemble(Object value) {
         return (DbEnum) value;
     }

     @Override
     public Object assemble(Serializable cached, Object owner) {
         return cached;
     }

     @Override
     public Object replace(Object original, Object target, Object owner) {
         return original;
     }

     @Override
     @SuppressWarnings("unchecked")
     public void setParameterValues(Properties parameters) {
         String enumClassName = parameters.getProperty("enumClass");
         try {
             enumClass = ReflectHelper.classForName(enumClassName, this.getClass()).asSubclass(Enum.class);
             if (!ReflectHelper.implementsInterface(enumClass, DbEnum.class)) {
                 throw new HibernateException("Enum does not implement DBEnum");
             }
         } catch (ClassNotFoundException exception) {
             throw new HibernateException("Enum class not found", exception);
         }
     }
 }

上面工具类里面的interface(DbEnum, LocalString)请参考上一篇mybatis里面的：http://www.cnblogs.com/cc-java/p/6593589.html

工具类写好了 接下来需要在对象里面注解属性（对象是基于annotations的）：

    @NotNull
    @Column(nullable = false)
    @Index(name = "order_state_idx")
    @Type(type = "com.lcc.core.domain.DbEnumType", parameters = {
            @Parameter(name = "enumClass", value = "com.lcc.api.domain.enums.order.SkuStatusType") })
    private SkuStatusType state;

到这里差不多hibernate字段映射枚举类型就完成了。