如何在 JPA 和 Hibernate 中使用 Java 8 LocalDateTime [英] How to use the Java 8 LocalDateTime with JPA and Hibernate

问题描述

我有以下类描述片段:

... 
@Column(name = "invalidate_token_date")
@Temporal(TemporalType.TIMESTAMP)
private LocalDateTime invalidateTokenDate;
....

此代码不适用于 Hibernate 4，因为 @Temporal 不支持 LocalDateTime.

This code doesn't work on Hibernate 4 because @Temporal doesn't support LocalDateTime.

我从 Joda-Time 看到了关于如何使用 LocalDateTime 的建议，但我使用的是 Java 8.

I saw the suggestion on how to use LocalDateTime from Joda-Time but I use Java 8.

推荐答案

由于 Hibernate 4 不支持它，您需要实现一个用户类型，如 这个 示例.

Since Hibernate 4 doesn't support it you need to implement a user type as shown in this example.

import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.type.StandardBasicTypes;
import org.hibernate.usertype.EnhancedUserType;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.Date;

public class LocalDateTimeUserType implements EnhancedUserType, Serializable {

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

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

    @Override
    public Class returnedClass() {
        return LocalDateTime.class;
    }

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

    @Override
    public int hashCode(Object object) throws HibernateException {
        return object.hashCode();
    }


    @Override
    public Object nullSafeGet(ResultSet resultSet, String[] names, SessionImplementor session, Object owner)
            throws HibernateException, SQLException {
        Object timestamp = StandardBasicTypes.TIMESTAMP.nullSafeGet(resultSet, names, session, owner);
        if (timestamp == null) {
            return null;
        }
        Date ts = (Date) timestamp;
        Instant instant = Instant.ofEpochMilli(ts.getTime());
        return LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
    }

    @Override
    public void nullSafeSet(PreparedStatement preparedStatement, Object value, int index, SessionImplementor session)
            throws HibernateException, SQLException {
        if (value == null) {
            StandardBasicTypes.TIMESTAMP.nullSafeSet(preparedStatement, null, index, session);
        } else {
            LocalDateTime ldt = ((LocalDateTime) value);
            Instant instant = ldt.atZone(ZoneId.systemDefault()).toInstant();
            Date timestamp = Date.from(instant);
            StandardBasicTypes.TIMESTAMP.nullSafeSet(preparedStatement, timestamp, index, session);
        }
    }

    @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 value) throws HibernateException {
        return cached;
    }

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

    @Override
    public String objectToSQLString(Object object) {
        throw new UnsupportedOperationException();
    }

    @Override
    public String toXMLString(Object object) {
        return object.toString();
    }

    @Override
    public Object fromXMLString(String string) {
        return LocalDateTime.parse(string);
    }

}

然后可以在带有@Type 注释的映射中使用新的用户类型.例如

The new usertype can then be used in the mapping with the @Type annotation. For e.g.

@Type(type="com.hibernate.samples.type.LocalDateTimeUserType")
@Column(name = "invalidate_token_date")
private LocalDateTime invalidateTokenDate;

@Type 注解需要实现 userType 接口的类的完整路径；这是生成映射列的目标类型的工厂.

The @Type annotation needs a full path to the class that implements the userType interface; this is the factory for producing the target type of the mapped column.

这里是 如何在 JPA2.1 中做同样的事情

Here's how to do the same thing in JPA2.1

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