以前看到一本書(shū)上寫(xiě)的,有關(guān)定義實(shí)體BEAN的一些細(xì)節(jié),直到今天才知道其中的差別
代碼1:
/*
* Test.java
*
* Created on 2006年12月15日, 上午12:06
*
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
*/
package com.hadeslee.entity;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
/**
* Entity class Test
*
* @author lbf
*/
@Entity
public class Test implements Serializable {
private Long id;
private String name,sex,age;
private int idCard;
/** Creates a new instance of Test */
public Test() {
}
/**
* Gets the id of this Test.
* @return the id
*/
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
public Long getId() {
return this.id;
}
/**
* Sets the id of this Test to the specified value.
* @param id the new id
*/
public void setId(Long id) {
this.id = id;
}
public void setNameID(int ids){
this.idCard=ids;
}
public int getNameID(){
return idCard;
}
/**
* Returns a hash code value for the object. This implementation computes
* a hash code value based on the id fields in this object.
* @return a hash code value for this object.
*/
@Override
public int hashCode() {
int hash = 0;
hash += (this.id != null ? this.id.hashCode() : 0);
return hash;
}
/**
* Determines whether another object is equal to this Test. The result is
* true if and only if the argument is not null and is a Test object that
* has the same id field values as this object.
* @param object the reference object with which to compare
* @return true if this object is the same as the argument;
* false otherwise.
*/
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Test)) {
return false;
}
Test other = (Test)object;
if (this.id != other.id && (this.id == null || !this.id.equals(other.id))) return false;
return true;
}
/**
* Returns a string representation of the object. This implementation constructs
* that representation based on the id fields.
* @return a string representation of the object.
*/
@Override
public String toString() {
return "com.hadeslee.entity.Test[id=" + id + "]";
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
}
代碼2:
/*
* Test.java
*
* Created on 2006年12月15日, 上午12:06
*
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
*/
package com.hadeslee.entity;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
/**
* Entity class Test
*
* @author lbf
*/
@Entity
public class Test implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name,sex,age;
private int idCard;
/** Creates a new instance of Test */
public Test() {
}
/**
* Gets the id of this Test.
* @return the id
*/
public Long getId() {
return this.id;
}
/**
* Sets the id of this Test to the specified value.
* @param id the new id
*/
public void setId(Long id) {
this.id = id;
}
public void setNameID(int ids){
this.idCard=ids;
}
public int getNameID(){
return idCard;
}
/**
* Returns a hash code value for the object. This implementation computes
* a hash code value based on the id fields in this object.
* @return a hash code value for this object.
*/
@Override
public int hashCode() {
int hash = 0;
hash += (this.id != null ? this.id.hashCode() : 0);
return hash;
}
/**
* Determines whether another object is equal to this Test. The result is
* true if and only if the argument is not null and is a Test object that
* has the same id field values as this object.
* @param object the reference object with which to compare
* @return true if this object is the same as the argument;
* false otherwise.
*/
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Test)) {
return false;
}
Test other = (Test)object;
if (this.id != other.id && (this.id == null || !this.id.equals(other.id))) return false;
return true;
}
/**
* Returns a string representation of the object. This implementation constructs
* that representation based on the id fields.
* @return a string representation of the object.
*/
@Override
public String toString() {
return "com.hadeslee.entity.Test[id=" + id + "]";
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
}
代碼1和代碼2唯一的差別就是@Id的注釋地方不同了
同樣是注釋主鍵,當(dāng)在直接用在變量上注釋時(shí),如果其它的成員變量沒(méi)有指定名字,則數(shù)據(jù)庫(kù)生成的表的各列名字將以定義的成員變量的變量名為準(zhǔn)
當(dāng)用在getter方法注釋時(shí),則數(shù)據(jù)庫(kù)生成的表的各列名字將取getXXXX的XXXX名字,將不再取定義的成員變量名
像上面的例子中,代碼1會(huì)有IdCard這一列,則代碼2取而代之的將是NameID這一列.這看上去是一個(gè)小小的差別,但是了解了終究是好事.呵呵.終于懂清楚在get上注釋和直接在成員變量上注釋的差別了,一般來(lái)說(shuō)是不會(huì)有什么差別的,一般標(biāo)準(zhǔn) 的JAVABEAN都是成員變量名和getter,setter簽名一樣的.
盡管千里冰封
依然擁有晴空
你我共同品味JAVA的濃香.
posted on 2007-09-11 15:45
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