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。