hibernate(jpa)复合主键annotation声明方法

最新推荐文章于 2020-06-30 07:33:58 发布

原创最新推荐文章于 2020-06-30 07:33:58 发布 · 133 阅读

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文章标签：

#JPA #Hibernate #.net

本文介绍了一种使用复合主键的数据库表设计方法，并详细展示了如何通过Hibernate（JPA）进行实体类与复合主键类的映射。

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在设计数据库表的时候，往往会设计出带有复合主键的表，即表的记录由多个字段联合标识，如：

表
CREATE TABLE TB_HOUR_DATA
(
  STAT_DATE  DATE                   NOT NULL,
  PATH_ID    NUMBER(20)             NOT NULL,
  VALUE      VARCHAR2(512 BYTE),
  TYPE       NUMBER(1)              NOT NULL
)其中，复合主键为（STAT_DATE，PATH_ID，TYPE）

针对这种情况，hibernate（jpa） 的 annotation 映射声明如下：
1、复合主键类HourDataPK
package net.kong.wolf.stat.db.entity;

import java.io.Serializable;
import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Embeddable;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

@Embeddable
public class HourDataPK implements Serializable {

    /** *//**
     * 
     */
    private static final long serialVersionUID = 1L;

    @ManyToOne
    @JoinColumn(name = "path_id", nullable = false)
    private Path path;

    @Column(name = "stat_date")
    @Temporal(TemporalType.DATE)
    private Date statDate;

    private int type;

    public Path getPath() {
        return path;
    }

    public void setPath(Path path) {
        this.path = path;
    }

    public Date getStatDate() {
        return statDate;
    }

    public void setStatDate(Date statDate) {
        this.statDate = statDate;
    }

    public int getType() {
        return type;
    }

    public void setType(int type) {
        this.type = type;
    }
}

2、实体类HourData：
package net.kong.wolf.stat.db.entity;

import java.io.Serializable;

import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Table;

import net.kong.wolf.stat.core.Text;

@Entity
@Table(name = "TB_HOUR_DATA")
public class HourData implements Serializable {

    /** *//**
     * 
     */
    private static final long serialVersionUID = 1L;

    @EmbeddedId
    private HourDataPK pk;

    private String value;

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

    public int[] getHours() {
        return parseValue(value);
    }

    private int[] parseValue(String value) {
        int[] result = new int[24];
        for (int i = 0; i < 24; i++) {
            result[i] = -1;
        }
        if (value == null) {
            return result;
        }
        String[] hs = Text.splitCSV(value);
        int len = Math.min(24, hs.length);
        for (int i = 0; i < len; i++) {
            result[i] = Text.parseInt(hs[i], -1);
        }
        return result;
    }

    public void setHours(int[] hours) {
        int[] tHours = parseValue(value);
        StringBuilder sb = new StringBuilder();
        int len = Math.min(24, hours.length);
        for (int i = 0; i < len; i++) {
            sb.append(hours[i] < 0 ? tHours[i] : hours[i]).append(',');
        }
        sb.deleteCharAt(sb.length() - 1);
        this.value = sb.toString();
    }

    public HourDataPK getPk() {
        return pk;
    }

    public void setPk(HourDataPK pk) {
        this.pk = pk;
    }
}