2010.01.14——hibernate annotatio复合主键并解决2010.01.13的问题

2010.01.14——hibernate annotatio复合主键并解决2010.01.13的问题
昨天的问题，我终于找到问题所在了，原因是我的ST_PPTN_R这个pojo类有问题

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.IdClass;
import javax.persistence.Table;

@Entity
@Table(name="ST_PPTN_R")
public class ST_PPTN_R {
	@Id
	@Column(length=8)
	private String STCD;
	@Id
	@Column
	private Date TM;
	@Column(precision=5,scale=1)
	private Double DRP;
	private Double INTV;
	private Double PDR;
	@Column(precision=5,scale=1)
	private Double DYP;
	@Column(length=1)
	private String WTH;
	public String getSTCD() {
		return STCD;
	}
	public void setSTCD(String stcd) {
		STCD = stcd;
	}
	public Date getTM() {
		return TM;
	}
	public void setTM(Date tm) {
		TM = tm;
	}
	public Double getDRP() {
		return DRP;
	}
	public void setDRP(Double drp) {
		DRP = drp;
	}
	public Double getINTV() {
		return INTV;
	}
	public void setINTV(Double intv) {
		INTV = intv;
	}
	public Double getPDR() {
		return PDR;
	}
	public void setPDR(Double pdr) {
		PDR = pdr;
	}
	public Double getDYP() {
		return DYP;
	}
	public void setDYP(Double dyp) {
		DYP = dyp;
	}
	public String getWTH() {
		return WTH;
	}
	public void setWTH(String wth) {
		WTH = wth;
	}
	public ST_PPTN_R(String STCD,Date TM,Double DYP){
		super();
		this.STCD = STCD;
		this.TM = TM;
		if(DYP==null)
			DYP = 0.0;
		this.DYP = DYP;
	}
	public ST_PPTN_R(){}

}

STCD和TM应该是联合主键的，而我就写了两个@ID，所以会一直报错说找不到TM的

那么现在就是要用hibernate annotation来设置联合主键了，我在网上看了好多方法，但是都要修改pojo类，而我后面要用到hql的动态实例查询，所以不能修改pojo类，我的解决方法如下：

pojo类：

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.IdClass;
import javax.persistence.Table;

@IdClass(STCD_TM.class)  //注意：变化在这里
@Entity
@Table(name="ST_PPTN_R")
public class ST_PPTN_R {
	@Id
	@Column(length=8)
	private String STCD;
	@Id
	@Column
	private Date TM;
	@Column(precision=5,scale=1)
	private Double DRP;
	private Double INTV;
	private Double PDR;
	@Column(precision=5,scale=1)
	private Double DYP;
	@Column(length=1)
	private String WTH;
	public String getSTCD() {
		return STCD;
	}
	public void setSTCD(String stcd) {
		STCD = stcd;
	}
	public Date getTM() {
		return TM;
	}
	public void setTM(Date tm) {
		TM = tm;
	}
	public Double getDRP() {
		return DRP;
	}
	public void setDRP(Double drp) {
		DRP = drp;
	}
	public Double getINTV() {
		return INTV;
	}
	public void setINTV(Double intv) {
		INTV = intv;
	}
	public Double getPDR() {
		return PDR;
	}
	public void setPDR(Double pdr) {
		PDR = pdr;
	}
	public Double getDYP() {
		return DYP;
	}
	public void setDYP(Double dyp) {
		DYP = dyp;
	}
	public String getWTH() {
		return WTH;
	}
	public void setWTH(String wth) {
		WTH = wth;
	}
	public ST_PPTN_R(String STCD,Date TM,Double DYP){
		super();
		this.STCD = STCD;
		this.TM = TM;
		if(DYP==null)
			DYP = 0.0;
		this.DYP = DYP;
	}
	public ST_PPTN_R(){}

}

复合主键类：

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

public class STCD_TM implements Serializable{
	private String STCD;
	private Date TM;
	public String getSTCD() {
		return STCD;
	}
	public void setSTCD(String stcd) {
		STCD = stcd;
	}
	public Date getTM() {
		return TM;
	}
	public void setTM(Date tm) {
		TM = tm;
	}
	public int hashCode(){
		return (int) STCD.hashCode();
    }

	public boolean equals(Object obj){
		if (obj == this) return true;
		if (!(obj instanceof STCD_TM)) return false;
		if (obj == null) return false;
		STCD_TM st = (STCD_TM) obj;
		return st.TM == TM && st.STCD.equals(STCD);
    }

}

这里这个复合主键类有几点要注意的；
1.类里面的字段或属性的类型和名称必须与使用 @Id 进行批注的实体主键字段或属性的类型和名称相对应

2.它必须为 public，并且必须有一个 public 无参数构造函数。

3.它必须是可序列化的。

4.它必须定义 equals 和 hashCode 方法。