javax persistencejava中的映射是怎样实现的?

java中的映射是怎样实现的?

建议做法如下： 第一，写一个符合javaBean标准的实体类，类的属性名称和类型分别与数据库的字段对应，并加上无参构造方法和get、set方法； 第二，使用注解配置映射关系，用@Entity注解该类是一个实体类，用@Table(name = "表名")注解该实体类映射的表名，通过在每一个属性的get方法上添加@Column(name = "列名")注解该属性映射的列； 第三，配置主键，找出表主键映射的那个属性，用@Id在该属性的get方法上注解该属性为Id。（根据具体需要，可能还要做一些更详细的配置） 参考代码如下： import?javax.persistence.Column; import?javax.persistence.Entity; import?javax.persistence.Id; import?javax.persistence.Table; .hibernate.annotations.Parameter; /** ?*? ?*?用户 ?*/ @Entity?//说明该类是实体类 @Table(name?=?"USER")//说明该类映射的是表USER public?class?TUser?implements?java.io.Serializable?{ ????private?String?userID;?//?用户id ????private?String?userName;?//?用户名称 ????private?String?loginName;?//?登录名称 ????private?String?password;?//?密码 ????private?Integer?status;?//?状态 ????private?java.util.Date?lastLoginTime;?//?上次登录时间 ????private?java.util.Date?regTime;?//?注册时间 ????@Id//说明该属性映射的是表USER的主键 ????@Column(name?=?"UserID",?unique?=?true,?nullable?=?false) ????//该属性映射的是表USER的UserId字段，非空且唯一 ????public?String?getUserID()?{ ????????return?this.userID; ????} ????public?void?setUserID(String?userID)?{ ????????this.userID?=?userID; ????} ????@Column(name?=?"UserName") ????public?String?getUserName()?{ ????????return?userName; ????} ????public?void?setUserName(String?userName)?{ ????????this.userName?=?userName; ????} ????@Column(name?=?"LoginName") ????public?String?getLoginName()?{ ????????return?this.loginName; ????} ????public?void?setLoginName(String?loginName)?{ ????????this.loginName?=?loginName; ????} ????@Column(name?=?"Password") ????public?String?getPassword()?{ ????????return?this.password; ????} ????public?void?setPassword(String?password)?{ ????????this.password?=?password; ????} ????@Column(name?=?"Status") ????public?Integer?getStatus()?{ ????????return?status; ????} ????public?void?setStatus(Integer?status)?{ ????????this.status?=?status; ????} ????@Column(name?=?"LastLoginTime") ????public?java.util.Date?getLastLoginTime()?{ ????????return?lastLoginTime; ????} ????public?void?setLastLoginTime(java.util.Date?lastLoginTime)?{ ????????this.lastLoginTime?=?lastLoginTime; ????} ????@Column(name?=?"RegTime") ????public?java.util.Date?getRegTime()?{ ????????return?regTime; ????} ????public?void?setRegTime(java.util.Date?regTime)?{ ????????this.regTime?=?regTime; ????} ????@Override ????public?int?hashCode()?{ ????????int?prime?=?0; ????????prime?+=?this.getUserID().hashCode(); ????????return?prime; ????} ????@Override ????public?boolean?equals(Object?obj)?{ ????????boolean?isEquals?=?false; ????????if?(obj?!=?null?&&?this.getClass()?==?obj.getClass())?{ ????????????TUser?clazz?=?(TUser)?obj; ????????????if?(clazz.getUserID().equals(this.getUserID())) ????????????????isEquals?=?true; ????????????return?isEquals; ????????} ????????return?isEquals; ????} }