hibernate註解的使用(1)

（自己的筆記）
以一個Admin類作為說明

1.首先
@Entity 註解將一個類聲明為實體Bean
@Table 映射數句庫表

2.創建表的主鍵

@Id用來註冊主屬性
@GeneratedValue來說明主鍵的自增長
3.創建列

@Column 註解將屬性映射到列
@Column(
   name="columnName"; (1) 列名
   boolean unique() default false; (2)    是否在該列上設置唯一約束
   boolean nullable() default true; (3)   列可空？
   boolean insertable() default true; (4) 該列是否作為生成 insert語句的一個列
   boolean updatable() default true; (5)  該列是否作為生成 update語句的一個列
   String columnDefinition() default""; (6)  預設值
   String table() default "";(7)             定義對應的表（deault 是主表）
   int length() default 255; (8)              列長度
   int precision() default 0; // decimalprecision (9)  decimal精度
   int scale() default 0; // decimal scale        (10) decimal長度
}

4.註解完成之後，通過xml連接到資料庫

5.最後，通過Session測試註解

//插入語句
    public void insertData() {
        Session session=HibernateUtils.getOpenSession();
        Transaction ts=session.beginTransaction();
        try {
            session.save(new Admin("admin","1234"));
            
        }
        catch(Exception e){
            System.out.println("error");
        }
        ts.commit();
        session.close();
        
    }

package main.java;

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

@Entity                                //實體
@Table(name="admin")                //創建表
public class Admin {
    private int adminID;            //管理員ID
    private String adminName;        //管理員賬號
    private String adminPassword;    //管理員密碼
    @Id                                //主鍵
    @GeneratedValue                    //自增長
    public int getAdminID() {
        return adminID;
    }
    public void setAdminID(int adminID) {
        this.adminID = adminID;
    }
    @Column(name="adminName",length=20,unique=true)
    public String getAdminName() {
        return adminName;
    }
    public void setAdminName(String adminName) {
        this.adminName = adminName;
    }
    @Column(name="adminPassword",length=20,unique=false)
    public String getAdminPassword() {
        return adminPassword;
    }
    public void setAdminPassword(String adminPassword) {
        this.adminPassword = adminPassword;
    }
    public Admin(int adminID, String adminName, String adminPassword) {
        super();
        this.adminID = adminID;
        this.adminName = adminName;
        this.adminPassword = adminPassword;
    }
    public Admin(String adminName, String adminPassword) {
        super();
        this.adminName = adminName;
        this.adminPassword = adminPassword;
    }
    public Admin(int adminID) {
        super();
        this.adminID = adminID;
    }
    @Override
    public String toString() {
        return "Admin [adminID=" + adminID + ", adminName=" + adminName + ", adminPassword=" + adminPassword + "]";
    }
}