Hibernate 悲观锁 的兑现

Hibernate 悲观锁 的实现

使用一个线程安全的Session:SessionFactory.getCurrentSession()

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需要配置Hibernate.cfg.xml 属性current_session_context_class = thread
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从数据库获取数据时,要加锁session.get(SomeClass.Class,id,LockMode.UPGRADE)
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试了一晚上,用Mysql做的测试,居然不行...下面的代码仅在Oracle下测试通过
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实体类
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public class Book { private int bid; private String name; private boolean borrow = false; private String owner;} //省略无参构造函数和getter/setter    

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borrow布尔类型变量用于标识书是否被借出
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owner 用于标识当前拥有者
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测试线程类(测试多线程并发访问情况下悲观锁的效果)
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public class Student extends Thread { private int bookid; private String stdname; public Student(String name,int bookid){  this.bookid = bookid;  this.stdname = name; } public void run(){    if(this.borrowBook()){   System.out.println(this.stdname + "借书 成功!!!");  }else{   System.out.println(this.stdname + "借书 失败!!!");  } } public boolean borrowBook(){  Session ss = null;  Transaction ts = null;  Book book = null;  try{   ss = DBFactory.sf.openSession();   ts = ss.beginTransaction();   book = (Book) ss.get(Book.class,bookid, LockMode.UPGRADE);   if(book.isBorrow()){ //书已经借出的情况返回false    System.out.println("isborrow_false");    return false;   }   book.setBorrow(true);   book.setOwner(this.stdname);   ss.save(book);   ts.commit();    return true;  //借书成功,返回true  }catch(Exception e){   ts.rollback();   e.printStackTrace();   System.out.println("Exception_false");   return false; //出错的时候返回false  }finally{   ss.close();  } }}

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Hibernate 配置文件 <property name="current_session_context_class">thread</property>
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产生Session的工具类
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public class DBFactory { public static SessionFactory sf = null; static{  sf = new Configuration().configure().buildSessionFactory(); } public static Session getSession(){  return sf.getCurrentSession();   //注意,此处返回的是线程安全的currentSession }} 

?测试类
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public class Test {  public static void main(String[] args) {//  addBook();   //用于构造books表的方法调用  Student lixun = new Student("Lixun",1);    //开启两个独立线程去借书  lixun.start();  Student zhougege = new Student("zhougege",1);  zhougege.start();    }  public static void addBook(){ //用于构造books表的方法  Book book = new Book();  book.setName("**Mei");  Session ss = null;  Transaction ts = null;  try{   ss = DBFactory.sf.openSession();   ts = ss.beginTransaction();   ss.save(book);   ts.commit();   ss.close();  }catch(Exception e){   ts.rollback();   e.printStackTrace();  } }}

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