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;@Embeddablepublic 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; }}
以诚感人者,人亦诚而应。