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jdbc-batch processing

��h�� — Wed, 11 Oct 2006 06:40:00 GMT

the addBatch() method is basically nothing more than a tool fro assigning a bunch of sql statements to a jdbc statement object for execution together

PreparedStatement stmt=conn.prepareStatement(
      "update account set balance=? where acct_id=?");
int[] rows;
for(int i=0;i    stmt.setInt(1,i);
    stmt.setLong(2,i);
    stmt.addBatch();
}
rows=stemt.executeBatch();

��h�� 2006-10-11 14:40 发表评论

��h�� — Wed, 11 Oct 2006 06:39:00 GMT

1 oracle 的实�?br /> 语句一
SELECT ID, [FIELD_NAME,...] FROM TABLE_NAME WHERE ID IN ( SELECT ID FROM (SELECT ROWNUM AS NUMROW, ID FROM TABLE_NAME WHERE 条�g1 ORDER BY 条�g2) WHERE NUMROW > 80 AND NUMROW < 100 ) ORDER BY 条�g3;
语句二：
SELECT * FROM (( SELECT ROWNUM AS NUMROW, c.* from (select [FIELD_NAME,...] FROM TABLE_NAME WHERE 条�g1 ORDER BY 条�g2) c) WHERE NUMROW > 80 AND NUMROW < 100 ) ORDER BY 条�g3;

select * from (select rownum as numrow from table_name where numrow>80 and numrow<100 )
不能直接使用 select * from rownum>100 and rownum<200;
in oracle return null;
2 sql server 的实�?br />3 mysql 的实�?/p>

select id from table_name where id in
                                   select * from (select rownum as numrow ,id from tabl_name)
                                             where numrow>80 and num<100;

��h�� 2006-10-11 14:39 发表评论

jdbc-prepare sql

��h�� — Wed, 11 Oct 2006 06:38:00 GMT

1 prepared sql
oracle provide two kinds of prepared SQL prepared statements and store procedures.Prepared SQL provide an advantage over the simple sql statements you have convered so far.if you execute the same prepared sql more than once,the database remains ready for your sql without having to rebuild the query plan.
1) Prepared Statements
PreparedStatement statement=conn.preparedStatement(
     "update account set balance=? where id=?");
for(int i=0;i    statement.setFloat(1,accounts[i].getBalance());
    statement.setInt(2,i);
    statement.execut();
    stateement.clearParameters();
}
commit();
statement.close;
2) Stored Procedure
try {
    CallableStatement statement;
    int i;

    statement = c.prepareCall("{call sp_interest[(?,?)]}");

    statement.registerOutParameter(2, java.sql.Types.FLOAT);
    for(i=1; i        statement.setInt(1, accounts[i].getId( ));
        statement.execute( );
        System.out.println("New balance: " + statement.getFloat(2));
    }
    c.commit( );
    statement.close( );
    c.close( );
}

��h�� 2006-10-11 14:38 发表评论

java 调用存储�q�程转蝲

��h�� — Wed, 11 Oct 2006 06:37:00 GMT

本文阐述了怎么使用DBMS存储�q�程。我阐述了��用存储过�E�的基本的和高��Ҏ��，比如�q�回ResultSet。本文假设你对DBMS和JDBC已经非常熟悉�Q�也假设你能够毫无障��地阅读其它语言写成的代码（即不是Java的语�a��Q�，但是�Q��ƈ不要求你有�Q何存储过�E�的�~�程�l�历�?
存储�q�程是指保存在数据库�q�在数据库端执行的程序。你可以使用�Ҏ��的语法在Java�c�M��调用存储�q�程。在调用�Ӟ��存储�q�程的名�U�及指定的参数通过JDBC�q�接发送给DBMS�Q�执行存储过�E��ƈ通过�q�接�Q�如果有�Q�返回结果�?
使用存储�q�程拥有和��用基于EJB或CORBA�q�样的应用服务器一��L��好处。区别是存储�q�程可以从很多流行的DBMS中免费��用，而应用服务器大都非常昂贵。这�q�不只是许可证费用的问题。��用应用服务器所需要花费的��理、编写代码的费用�Q�以及客��L��序所增加的复杂性，都可以通过DBMS中的存储�q�程所整个地替代�?
你可以��用Java�Q�Python�Q�Perl或C�~�写存储�q�程�Q�但是通常使用你的DBMS所指定的特定语�a�。Oracle使用PL/SQL�Q�PostgreSQL使用pl/pgsql�Q�DB2使用Procedural SQL。这些语�a�都非常相伹{��在它们之间�U�L��存储�q�程�q�不比在Sun的EJB规范不同实现版本之间�U�L��Session Bean困难。�ƈ且，存储�q�程是�ؓ嵌入SQL所设计�Q�这使得它们比Java或C�{�语�a�更加友好地方式表达数据库的机制�?
因�ؓ存储�q�程�q�行在DBMS自��n�Q�这可以帮助减少应用�E�序中的�{�待旉��。不是在Java代码中执�?个或5个SQL语句�Q�而只需要在服务器端执行1个存储过�E�。网�l�上的数据往�q�次数的减少可以戏剧性地优化性能�?

使用存储�q�程

��单的老的JDBC通过CallableStatement�c�L��持存储过�E�的调用。该�c�d��际上是PreparedStatement的一个子�c�R��假设我们有一个poets数据库。数据库中有一个设�|�诗人逝世�q�龄的存储过�E�。下面是对老酒鬼Dylan Thomas�Q�old soak Dylan Thomas�Q�不指定是否有关典故、文化，��h��评指正。译注）�q�行调用的详�l�代码：

try{
int age = 39;

String poetName = "dylan thomas";

CallableStatement proc = connection.prepareCall("{ call set_death_age(?, ?) }");

proc.setString(1, poetName);

proc.setInt(2, age);

cs.execute();

}catch (SQLException e){ // ....}

传给prepareCall�Ҏ��的字串是存储�q�程调用的书写规范。它指定了存储过�E�的名称�Q�？代表了你需要指定的参数�?
和JDBC集成是存储过�E�的一个很大的便利�Q��ؓ了从应用中调用存储过�E�，不需要存根（stub�Q�类或者配�|�文�Ӟ��除了你的DBMS的JDBC驱动�E�序外什么也不需要�?
当这�D�代码执行时�Q�数据库的存储过�E�就被调用。我们没有去获取�l�果�Q�因��存储�q�程�q�不�q�回�l�果。执行成功或��p�|��通过例外得知。失败可能意味着调用存储�q�程时的��p�|�Q�比如提供的一个参数的�c�d��不正��）�Q�或者一个应用程序的��p�|�Q�比如抛��Z��个例外指�C�在poets数据库中�q�不存在“Dylan Thomas”）

�l�合SQL操作与存储过�E?

映射Java对象到SQL表中的行相当��单，但是通常需要执行几个SQL语句�Q�可能是一个SELECT查找ID�Q�然后一个INSERT插入指定ID的数据。在高度规格化（�W�合更高的范式，译注�Q�的数据库模式中�Q�可能需要多个表的更斎ͼ�因此需要更多的语句。Java代码会很快地膨胀�Q�每一个语句的�|�络开销也迅速增加�?
��这些SQL语句转移��C��个存储过�E�中��大大简化代码，仅涉及一�ơ网�l�调用。所有关联的SQL操作都可以在数据库内部发生。�ƈ且，存储�q�程语言�Q�例如PL/SQL�Q�允�怋�用SQL语法�Q�这比Java代码更加自然。下面是我们早期的存储过�E�，使用Oracle的PL/SQL语言�~�写�Q?

create procedure set_death_age(poet VARCHAR2, poet_age NUMBER)

poet_id NUMBER;

begin SELECT id INTO poet_id FROM poets WHERE name = poet;

INSERT INTO deaths (mort_id, age) VALUES (poet_id, poet_age);

end set_death_age;

很独特？不。我打赌你一定期待看��C��个poets表上的UPDATE。这也暗�C�Z��使用存储�q�程实现是多么容易的一件事情。set_death_age几乎可以肯定是一个很烂的实现。我们应该在poets表中��d��一列来存储逝世�q�龄。Java代码中�ƈ不关心数据库模式是怎么实现的，因�ؓ它仅调用存储�q�程。我们以后可以改变数据库模式以提高性能�Q�但是我们不必修�Ҏ��们代码�?
下面是调用上面存储过�E�的Java代码�Q?

public static void setDeathAge(Poet dyingBard, int age) throws SQLException{

Connection con = null;

CallableStatement proc = null;

try {

con = connectionPool.getConnection();

proc = con.prepareCall("{ call set_death_age(?, ?) }");

proc.setString(1, dyingBard.getName());

proc.setInt(2, age);

proc.execute();

}

finally {

try { proc.close(); }

catch (SQLException e) {}

con.close();

}

��Z��保可维护性，��使用像这儿这��L��static�Ҏ��。这也��得调用存储过�E�的代码集中在一个简单的模版代码中。如果你用到许多存储�q�程�Q�就会发��C��需要拷贝、粘贴就可以创徏新的�Ҏ��。因��Z��码的模版化，甚至也可以通过脚本自动生��调用存储�q�程的代码�?

Functions

存储�q�程可以有返回��|��所以CallableStatement�c�L��c�M��getResultSet�q�样的方法来获取�q�回倹{��当存储�q�程�q�回一个值时�Q�你必须使用registerOutParameter�Ҏ��告诉JDBC驱动器该值的SQL�c�d��是什么。你也必��调整存储过�E�调用来指示该过�E�返回一个倹{�?
下面接着上面的例子。这�ơ我们查询Dylan Thomas逝世时的�q�龄。这�ơ的存储�q�程使用PostgreSQL的pl/pgsql�Q?

create function snuffed_it_when (VARCHAR) returns integer ''declare

poet_id NUMBER;

poet_age NUMBER;

begin

--first get the id associated with the poet.

SELECT id INTO poet_id FROM poets WHERE name = $1;

--get and return the age.

SELECT age INTO poet_age FROM deaths WHERE mort_id = poet_id;

return age;

end;'' language ''pl/pgsql'';

另外�Q�注意pl/pgsql参数名通过Unix和DOS脚本�?n语法引用。同�Ӟ��也注意嵌入的注释�Q�这是和Java代码相比的另一个优��性。在Java中写�q�样的注释当然是可以的，但是看�v来很凌�ؕ�Q��ƈ且和SQL语句��p��Q�必��d��入到Java String中�?
下面是调用这个存储过�E�的Java代码�Q?

connection.setAutoCommit(false);

CallableStatement proc = connection.prepareCall("{ ? = call snuffed_it_when(?) }");

proc.registerOutParameter(1, Types.INTEGER);

proc.setString(2, poetName);

cs.execute();

int age = proc.getInt(2);

如果指定了错误的�q�回值类型会怎样�Q�那么，当调用存储过�E�时��抛��Z��个RuntimeException�Q�正如你在ResultSet操作中��用了一个错误的�c�d��所��到的一栗��?

复杂的返回�?

关于存储�q�程的知识，很多人好像就熟悉我们所讨论的这些。如果这是存储过�E�的全部功能�Q�那么存储过�E�就不是其它�q�程执行机制的替换方案了。存储过�E�的功能比这强大得多�?
当你执行一个SQL查询�Ӟ��DBMS创徏一个叫做cursor�Q�游标）的数据库对象�Q�用于在�q�回�l�果中�P代每一行。ResultSet是当前时间点的游标的一个表�C�。这��是��Z��么没有缓存或者特定数据库的支持，你只能在ResultSet中向前移动�?
某些DBMS允许从存储过�E�中�q�回游标的一个引用。JDBC�q�不支持�q�个功能�Q�但是Oracle、PostgreSQL和DB2的JDBC驱动器都支持在ResultSet上打开到游标的指针�Q�pointer�Q��?
设想列出所有没有活到退休年龄的诗�h�Q�下面是完成�q�个功能的存储过�E�，�q�回一个打开的游标，同样也��用PostgreSQL的pl/pgsql语言�Q?

create procedure list_early_deaths () return refcursor as ''declare

toesup refcursor;

begin

open toesup for SELECT poets.name, deaths.age FROM poets, deaths -- all entries in deaths are for poets. -- but the table might become generic.

WHERE poets.id = deaths.mort_id AND deaths.age < 60;

return toesup;

end;'' language ''plpgsql'';

下面是调用该存储�q�程的Java�Ҏ��Q�将�l�果输出到PrintWriter�Q?
PrintWriter:

static void sendEarlyDeaths(PrintWriter out){

Connection con = null;

CallableStatement toesUp = null;

try {

con = ConnectionPool.getConnection();

// PostgreSQL needs a transaction to do this... con.

setAutoCommit(false); // Setup the call.

CallableStatement toesUp = connection.prepareCall("{ ? = call list_early_deaths () }");

toesUp.registerOutParameter(1, Types.OTHER);

toesUp.execute();

ResultSet rs = (ResultSet) toesUp.getObject(1);

while (rs.next()) {

String name = rs.getString(1);

int age = rs.getInt(2);

out.println(name + " was " + age + " years old.");

}

rs.close();

}

catch (SQLException e) { // We should protect these calls. toesUp.close(); con.close();

}

因�ؓJDBC�q�不直接支持从存储过�E�中�q�回游标�Q�我们��用Types.OTHER来指�C�存储过�E�的�q�回�c�d��Q�然后调用getObject()�Ҏ��q�对�q�回��D��行强制类型�{换�?
�q�个调用存储�q�程的Java�Ҏ��是mapping的一个好例子。Mapping是对一个集上的操作�q�行抽象的方法。不是在�q�个�q�程上返回一个集�Q�我们可以把操作传送进��L��行。本例中�Q�操作就是把ResultSet打印��C��个输出流。这是一个值得举例的很常用的例子，下面是调用同一个存储过�E�的另外一个方法实玎ͼ�

public class ProcessPoetDeaths{

public abstract void sendDeath(String name, int age);

}

static void mapEarlyDeaths(ProcessPoetDeaths mapper){

Connection con = null;

CallableStatement toesUp = null;

try {

con = ConnectionPool.getConnection();

con.setAutoCommit(false);

CallableStatement toesUp = connection.prepareCall("{ ? = call list_early_deaths () }");

toesUp.registerOutParameter(1, Types.OTHER);

toesUp.execute();

ResultSet rs = (ResultSet) toesUp.getObject(1);

while (rs.next()) {

String name = rs.getString(1);

int age = rs.getInt(2);

mapper.sendDeath(name, age);

}

rs.close();

} catch (SQLException e) { // We should protect these calls. toesUp.close();

con.close();

}

�q�允许在ResultSet数据上执行�Q意的处理�Q�而不需要改变或者复制获取ResultSet的方法：

static void sendEarlyDeaths(final PrintWriter out){

ProcessPoetDeaths myMapper = new ProcessPoetDeaths() {

public void sendDeath(String name, int age) {

out.println(name + " was " + age + " years old.");

}

};

mapEarlyDeaths(myMapper);

}

�q�个�Ҏ��使用ProcessPoetDeaths的一个匿名实例调用mapEarlyDeaths。该实例拥有sendDeath�Ҏ��的一个实玎ͼ�和我们上面的例子一��L��方式把结果写入到输出��。当�Ӟ��q�个技巧�ƈ不是存储�q�程�Ҏ��的，但是和存储过�E�中�q�回的ResultSet�l�合使用�Q�是一个非常强大的工具�?

�l�论

存储�q�程可以帮助你在代码中分��逻辑�Q�这基本上��L��有益的。这个分��ȝ��好处有：
• 快速创建应用，使用和应用一��h��变和改善的数据库模式�?
• 数据库模式可以在以后改变而不影响Java对象�Q�当我们完成应用后，可以重新设计更好的模式�?
• 存储�q�程通过更好的SQL嵌入使得复杂的SQL更容易理解�?
• �~�写存储�q�程比在Java中编写嵌入的SQL拥有更好的工��P��Q�大部分�~�辑器都提供语法高亮�Q?
• 存储�q�程可以在�Q何SQL命��o行中��试�Q�这使得调试更加�Ҏ��?

�q�不是所有的数据库都支持存储�q�程�Q�但是存在许多很��的实现�Q�包括免�?开源的和非免费的，所以移植�ƈ不是一个问题。Oracle、PostgreSQL和DB2都有�c�M��的存储过�E�语�a��Q��ƈ且有在线的社区很好地支持�?
存储�q�程工具很多�Q�有像TOAD或TORA�q�样的编辑器、调试器和IDE�Q�提供了�~�写、维护PL/SQL或pl/pgsql的强大的环境�?
存储�q�程��实增加了你的代码的开销�Q�但是它们和大多数的应用服务器相比，开销��得多。如果你的代码复杂到需要��用DBMS�Q�我��整个采用存储�q�程的方式�?/p>

��h�� 2006-10-11 14:37 发表评论

OpenSessionInViewFilter解决Web应用�E�序的问�?转自�Q�Potain 的BLOG

��h�� — Tue, 26 Sep 2006 03:01:00 GMT

OpenSessionInView

Created by potian. Last edited by admin 61 days ago. Viewed 181 times.

[edit] [attach]

Hibernate的Lazy初始�?:n关系�Ӟ��你必��M��证是在同一个Session内部使用�q�个关系集合�Q�不然Hiernate��抛��Z��外�?

另外�Q�你不愿意你的DAO��试代码每次都打开关系Session�Q�因此，我们一般会采用OpenSessionInView模式�?

OpenSessionInViewFilter解决Web应用�E�序的问�?

如果�E�序是在正常的Web�E�序中运行，那么Spring�?b style="COLOR: black; BACKGROUND-COLOR: #ffff66">OpenSessionInViewFilter能够解决问题�Q�它�Q?

protected void doFilterInternal(HttpServletRequest request, 
             HttpServletResponse response,
	     FilterChain filterChain) throws ServletException, IOException {
	SessionFactory sessionFactory = lookupSessionFactory();
	logger.debug("Opening Hibernate Session in OpenSessionInViewFilter");
	Session session = getSession(sessionFactory);
	TransactionSynchronizationManager.bindResource(sessionFactory, 
             new SessionHolder(session));
	try {
		filterChain.doFilter(request, response);
	}
	finally {
		TransactionSynchronizationManager.unbindResource(sessionFactory);
		logger.debug("Closing Hibernate Session in OpenSessionInViewFilter");
		closeSession(session, sessionFactory);
	}
}

可以看到�Q�这个Filter在request开始之前，把sessionFactory�l�定到TransactionSynchronizationManager�Q�和�q�个SessionHolder相关。这个意味着所有request执行�q�程中将使用�q�个session。而在��h��l�束后，��和�q�个sessionFactory对应的session解绑�Q��ƈ且关闭Session�?

��Z��么绑定以后，��可以防止每�ơ不会新开一个Session呢？看看HibernateDaoSupport的情况：

publicfinal void setSessionFactory(SessionFactory sessionFactory) {
    this.hibernateTemplate = new HibernateTemplate(sessionFactory);
  }
 protectedfinal HibernateTemplate getHibernateTemplate() {
  return hibernateTemplate;
 }

我们的DAO��用这个template�q�行操作�Q?

publicabstract class BaseHibernateObjectDao
	extends HibernateDaoSupport
	implements BaseObjectDao {protected BaseEntityObject getByClassId(finallong id) {
		BaseEntityObject obj =
			(BaseEntityObject) getHibernateTemplate()
				.execute(new HibernateCallback() {
publicObject doInHibernate(Session session)
				throws HibernateException {
				return session.get(getPersistentClass(), 
                                       newLong(id));
			}
		});
		return obj;
	}
public void save(BaseEntityObject entity) {
		getHibernateTemplate().saveOrUpdate(entity);
	}
public void remove(BaseEntityObject entity) {
		try {
			getHibernateTemplate().delete(entity);
		} catch (Exception e) {
			thrownew FlexEnterpriseDataAccessException(e);
		}
	}
public void refresh(final BaseEntityObject entity) {
		getHibernateTemplate().execute(new HibernateCallback() {
publicObject doInHibernate(Session session)
				throws HibernateException {
				session.refresh(entity);
				returnnull;
			}
		});
	}
public void replicate(finalObject entity) {
		getHibernateTemplate().execute(new HibernateCallback() {
publicObject doInHibernate(Session session)
				throws HibernateException {
				session.replicate(entity, 
                                ReplicationMode.OVERWRITE);
				returnnull;
			}
		});
	}

而HibernateTemplate试图每次在execute之前去获得Session�Q�执行完��力争关闭Session

publicObject execute(HibernateCallback action) throws DataAccessException {
	Session session = (!this.allowCreate ?
		SessionFactoryUtils.getSession(getSessionFactory(), 
                  false) :
		SessionFactoryUtils.getSession(getSessionFactory(),
                  getEntityInterceptor(),
                  getJdbcExceptionTranslator()));
	boolean existingTransaction =  
          TransactionSynchronizationManager.hasResource(getSessionFactory());
	if (!existingTransaction && getFlushMode() == FLUSH_NEVER) {
		session.setFlushMode(FlushMode.NEVER);
	}
	try {
		Object result = action.doInHibernate(session);
		flushIfNecessary(session, existingTransaction);
		return result;
	}
	catch (HibernateException ex) {
		throw convertHibernateAccessException(ex);
	}
	catch (SQLException ex) {
		throw convertJdbcAccessException(ex);
	}
	catch (RuntimeException ex) {
		// callback code threw application exception
		throw ex;
	}
	finally {
		SessionFactoryUtils.closeSessionIfNecessary(
                    session, getSessionFactory());
	}
}

而这个SessionFactoryUtils能否得到当前的session以及closeSessionIfNecessary是否真正关闭session�Q�端取决于这个session是否用sessionHolder和这个sessionFactory在我们最开始提到的TransactionSynchronizationManager�l�定�?

publicstatic void closeSessionIfNecessary(Session session, 
    SessionFactory sessionFactory)   
    throws CleanupFailureDataAccessException {
	if (session == null || 
	   TransactionSynchronizationManager.hasResource(sessionFactory)) {
		return;
	}
	logger.debug("Closing Hibernate session");
	try {
		session.close();
	}
	catch (JDBCException ex) {
		// SQLException underneath
		thrownew CleanupFailureDataAccessException(
		"Cannot close Hibernate session", ex.getSQLException());
	}
	catch (HibernateException ex) {
		thrownew CleanupFailureDataAccessException(
		"Cannot close Hibernate session", ex);
	}
}

HibernateInterceptor和OpenSessionInViewInterceptor的问�?

使用同样的方法，�q�两个Interceptor可以用来解决问题。但是关键的不同之处在于�Q�它们的力度只能定义在DAO或业务方法上�Q�而不是在我们的Test�Ҏ��上，除非我们把它们应用到TestCase的方法上�Q�但你不大可能�ؓTestCase��d��义一个接口，然后把Interceptor应用到这个接口的某些�Ҏ��上。直接��用HibernateTransactionManager也是一��L��。因此，如果我们有这��L��试�Q?

Category parentCategory  = new Category ();
	parentCategory.setName("parent");
	dao.save(parentCategory);	Category childCategory  = new Category();
        childCategory.setName("child");
	parentCategory.addChild(childCategory);
	dao.save(childCategory);
	Category savedParent = dao.getCategory("parent");
	Category savedChild = (Category ) savedParent.getChildren().get(0);
	assertEquals(savedChild, childCategory);

��意味着两�g事情�Q?

每次DAO执行都会启动一个session和关闭一个session
如果我们定义了一个lazy的关�p�，那么最后的Category savedChild = (Category ) savedParent.getChildren().get(0);��会让hibernate报错�?

解决�Ҏ��

一�U�方法是对TestCase应用Interceptor或者TransactionManager�Q�但�q�个恐怕会造成很多�ȝ��。除非是使用增强方式的AOP.我前期采用这�U�方�?Aspectwerkz)�Q�在Eclipse里面也跑得含好�?

另一�U�方法是在TestCase的setup和teardown里面实现和Filter完全一��L��处理�Q�其他的TestCase都从�q�个TestCase�l�承�Q�这�U�方法是我目前所使用的�?

Jolestar补充:openSessionInView的配�|�方�?

opensession
org.springframework.orm.hibernate3.support.OpenSessionInViewFilter

singleSession
false

��h�� 2006-09-26 11:01 发表评论

Spring -transaction

��h�� — Fri, 15 Sep 2006 03:00:00 GMT

1 Understand Transaction
1) Introduce Spring's transaction manager
a JDBC transactions





   b Hibernate transactions





2 Programing transaction in Spring
   One approach to adding transaction to your code is to programmly add transactional boundary using transiationTemplate class.
   Programming is good when you want complete control over transactional boundary.but you have to use spring specific class.In most case ,your tansactional needs will not require such precise control over transactional boundaries.That is why you will typically choolse to declare transaction support
public void enrollStudentInCourse() {
    transactionTemplate.execute(
    new TransactionCallback() {
      public Object doInTransaction(TransactionStatus ts) {
        try {
          // do stuff   Runs within doInTransaction()
        } catch (Exception e) {
          ts.setRollbackOnly(); //Calls setRollbackOnly() to roll Calls setRollbackOnly()                                 //to roll back
        }
          return null;   //If successful, transaction is committed
      }
    }
   );
}



     class="com.springinaction.training.service.CourseServiceImpl">




3 Declaring transactions
Spring's support for declarative transaction management is implementedd through Spirng's AOP framework.



        com.springinaction.training.service.CourseService



      //Bean being proxied

      //Transaction manager

      //Transaction attribute source

1) Understanding transaction attributes
In Spring transaction attribute is a description of how transaction policies should be
applied to a methods
   a Propagation behavior
    Propagation behavior                 What it means
    PROPAGATION_MANDATORY                indicate that the method must run within a                                                  transaction.If no transaction is in progress
                                         an exception will be thrown
    PROPAGATION_NESTED
    PROPAGATION_NEVER                    indicate that the method can not run withi a                                                transaction. if a transaction exist an exception                                            will be thrown.
    PROPAGATIOM_NOT_SUPPORT              Indicates that the method should not run within a                                           transaction. If an existing transaction is                                                  in progress, it will be suspended for the
                                         duration of the method.
    PROPAGATION_REQUIRED                 indicate that the current method must run within a                                          transaction.if an existing transaction is in                                                progress,the ,method will run with the transaction
                                         otherwise a new transaction will be started
    PROPAGATION_REQUIRENEW               indicates that the current must run within its own
                                         transaction.A new transaction is started and an                                             existing transaction will be suspend
    PROPAGATION_SUPPORT                  indicate the current mehtod does not require a                                          transaction.but may run if on is already in progress
    b Isolation levels
    Isolation level                    What it means
    ISOLATION_DEFAULT                  Using the defaul isolation level of the underlying                                          database
    ISOLATION_READ_UNCOMMITTED         Allows you read change that have not yet been commit
                                       May result in dirty read,phantom read,nonrepeatable                                         read
    ISOLATION_READ_COMMITTED           Allows reads from concurrent transactions that have
                                       bean committed.Dirty read are prevent.but platform                                          and norepeatable reads may still occur.
    ISOLATIOM_REPEATABLE_READ          Multiple read the same field will yield the same                                            result ,unless changed by the transaction                                                   itself.Dirty reads ,nonrepeatable are all prevented
                                       phantom may still occur
    ISOLATION_SERIALIZABLE             This fully ACID-compliant isolation level ensusme                                        that dirty read,unrepeatable read ,phantom read are                                        all prevented.And this is the most slowest isolation
                                       since it is typically accomplished by doing full                                        table lock on the tables in the transaction.

   c Read-Only
   If a transaction performs only read operation against the underlying datastore.when a transaction begin ,it only make sense to declare a transaction as read only on mehtods with
propagation behavior which start a new transaction.
   Furthermore ,if you are Hibernate as persistence mechanism,declaring a transaction as read only will reult in Hibernate flush mode being set to FLUST_NEVER.this tell hibernate to avoid synchroniztion of objects with database.
   d Transaction timeout
   Suppose that your transaction becomes unexpectedly long-running transaction.Because transaction may invole locks on the underlying database.Instead of waiting it out ,you can delcare a transaction to automaitically roll back.
   because timeout clock begin ticking when a transaction start. it only make sense to declare a transaction timeout on methods with propagation behavior that start a new transaction.
2) Declaring a simple transaction policy
       class="org.springframework.transaction.interceptor.
            DefaultTransactionAttribute">

    PROPAGATION_REQUIRES_NEW

    ISOLATION_REPEATABLE_READ

     class="org.springframework.transaction.interceptor.
            MatchAlwaysTransactionAttributeSource">



4 Declaring transactions by method name
1) Using NameMatchTransactionAttributeSource
The properties property of NameMatchTransactionAttributeSource maps mehtod to a transaction property descriptor. the property descriptor takes the following form:
Propagation,isolation,readOnly,-Exception,+Exception

    class="org.springframework.transaction.interceptor.
            NameMatchTransactionAttributeSource">



          PROPAGATION_REQUIRES_NEW



2) Specifying the transaction Isolation level
    class="org.springframework.transaction.interceptor.
            NameMatchTransactionAttributeSource">



        PROPAGATION_REQUIRES_NEW,ISOLATION_REPEATABLE_READ



3) Using real-only transaction
    class="org.springframework.transaction.interceptor.
            NameMatchTransactionAttributeSource">



        PROPAGATION_REQUIRED,ISOLATION_REPEATABLE_READ,readOnly



4)Specifying rollback rules
You can sepcify that a transaction be rollback on specify checked exception
    class="org.springframework.transaction.interceptor.
            NameMatchTransactionAttributeSource">



        PROPAGATION_REQUIRES_NEW,ISOLATION_REPEATABLE_READ,
        -CourseException




Exception can be marked as negative(-) or postive(+)
Negative exception will trigger the roll back if the exception (or sublclass of it) is thrown.Postive exception on the other hand indicate that the transacton should be commit
even if the exception is thrown
5)Using wildcard matches
     class="org.springframework.transaction.interceptor.
            NameMatchTransactionAttributeSource">



        PROPAGATION_SUPPORTS



6 Short-cut name match transaction




        PROPAGATION_REQUIRES_NEW

��h�� 2006-09-15 11:00 发表评论

spring -database

��h�� — Thu, 14 Sep 2006 03:45:00 GMT

一 Spring DAO philosophy
1 Understanding Spring's DataAccesssException
Spring's DAO frameworks donot throw teechnology-specific exceptions such as SQLException
or HibernateeExcepiton.Instead ,all exceptions thrown are subclasses of DataAccessException
2 You are not forced to handle DataAccessExceptions
DataAccessException is a RuntimeException,so it si an unchecked exception.Since these are quite often unrecoverable,you are not forced to handle these exception.
Instead ,you can catch the exception if recovery is possible.since DataAccessException is not only a RuntimeException,but it subclasses Spring's NestedRuntimeException. This menas that the root Exception is alwarys via NestedRuntimeException's getCause() method.
3 Work with DataSources
a getting a Datasource from JNDI
         class="org.springframework.jndi.JndiObjectFactoryBean">

    java:comp/env/jdbc/myDatasource


b Creating a Datasource connection pool
         class="org.apache.commons.dbcp.BasicDataSource">

    ${db.driver}

    ${db.url}

    ${db.username}

    ${db.password}

c Using a DataSource while testing
DriverManagerDataSource dataSource = new DriverManagerDataSource();
dataSource.setDriverClassName(driver);
dataSource.setUrl(url);
dataSource.setUsername(username);
dataSource.setPassword(password);
4 Consistent DAO support
Spring template class handle the invariant part of data access-controling the trancsaction
manage resource,handling exception .Implementation of callback interface define what is specific to your application--creating statement,binding parameter and marshalling result set.
Spring separates the fixed an vaiant parts of data access process into tow distince classes:
template and callbacks.Template manage the fixed parts of the process while callback are where you fill in the implement details;
one the top of template-callback desing ,spring framework provide a support class which your own data access subclass it. And the support class already have a property for holding a template.
�?Integerating Hibernate with Spring
1 Managing Hibernate resources
   you will keep a single instance of SessionFactory throughtout your application






you also want to manager how hibernate is configured


      net.sf.hibernate.
           dialect.MySQLDialect

�?br />
and the last thing is whick map files is read


     Student.hbm.xml
     Course.hbm.xml
     �?br />

     �?br />

Now you have fully configured your sessionfactory ,so we need do create an object which we
will access hibernate. As we know, we will use a template class
class="org.springframework.orm.hibernate.HibernateTemplate">

2 Accessing Hibernate through HibernatTemplate
The template-callback mechanism in Hibernatee is pretty simple.There is the HibernatTmpplate and one callback interface
public Student getStudent(final Integer id) {
return (Student) hibernateTemplate.execute(
    new HibernateCallback() {
      public Object doInHibernate(Session session)
          throws HibernateException {
        return session.load(Student.class, id);
      }
    });

The HibernateTemplate class provides some convience methods that implicit create a HibernateCallback instance:
(Student) hibernateTemplate.load(Student.class, id);
   hibernateTemplate.update(student);
hibernateTemplate.find("from Student student " +
                                "where student.lastName = ?",
                                lastName, Hibernate.STRING);
3 Subclassing HibernateDaoSupport
public class StudentDaoHibernate extends HibernateDaoSupport
    implements StudentDao {
�?br /> }
getHibernateTemplate()
getSession()

��h�� 2006-09-14 11:45 发表评论

��h�� — Thu, 14 Sep 2006 01:22:00 GMT

1 hibernate 一�U�缓�?br />Session
evict(Object o) 从缓存中清除指定的持久化对象
clear()         清除�~�存中所有对�?br />2 扚w��更新于批量删�?br /> 1) 扚w��更新
   Iterator customers=session.find("from Customer c where c.age>0");
   while(customers.hasNext()){
     Customer customer=(Customer)customers.next();
     customer.setAge(customer.getAge()+1);
   }
   tx.commit();
   session.close();

�~�点�Q�内存中加蝲了大量数�?br />        执行了多�ơupdate 语句

   改进
   Iterator customers=session.find("from Customer c where c.age>0");
   while(customers.hasNext()){
     Customer customer=(Customer)customers.next();
     customer.setAge(customer.getAge()+1);
     session.flush();
     session.evict(customer);
   }
   tx.commit();
   session.close();
   遗留问题
   执行了多�ơupdate 语句

   采用jdbc api �q�行调用
   Connection con=session.connection();
   PrepareStatement stmt=con.prepareStatement("update customers set age=age+1 where age>0");
   stmt.executeUpdate();
   tx.commit();
   另外�Q�也可以调用底层的存储过�E�进行批量更�?br />   create or replace procedure batchUpdateCustomer(p_age,in number) as
   begin
      update customer set age=age+1 where age>p_age;
   end;

   tx=session.beginTransaction();
   Connection con=session.connection();
   CallableStatement cstmt=con.prepareCall(batchUpdateCustomer);
   cstmt.setInt(1,0);
   cstmt.eqecuteUpdate();
   tx.commit();
   2) 扚w��数据的删�?br />    session.delete("from Customer c where c.age>0");
    实际调用的过�E?br />    session * from Customer where age>0;
    在把所有数据加载到内存之后执行多条delete 语句
    delete from customer where id=i;
     .......................
   改进办法采用jdbc api �q�行扚w��数据的删�?br />
   tx=session.beginTransaction();
   Connection con=session.connection();
   con.execute("delete from customers where age>0");
   tx.commit();

��h�� 2006-09-14 09:22 发表评论

hibernate -�c�d��

��h�� — Thu, 14 Sep 2006 01:20:00 GMT

Hibernate java sql oracle

integer or int             int or Integer           INTEGER
long                       long or Long             BIGINT
short                      short or Short           SMALLINT
byte                       byte or Byte             TINYINT
float                      float or Float           FLOAT
double                     double or Double         DOUBLE
big_decimal                java.math.BigDecimal     NUMBERBIC
character                  char java.lang.Character CHAR(1)
                           String
string                     String                    VARCHAR
boolean                    boolean or Boolean        BIT
date                       java.util.Date            DATE
                           java.sql.Date
time                       Date or java.sql.time     TIME
timestamp                  Date or java.sql.Timestamp TIMESTAMP
binary                     byte[]                    blog                   blog
text                       String                    clob                   clog
serializable                                         blog                   blog
clob                       java.sql.clob            clob                    clob
blob                       java.sql.blob             blog                   blob

��h�� 2006-09-14 09:20 发表评论

spring --wiring binding

��h�� — Mon, 04 Sep 2006 03:10:00 GMT

Containing your beans
Tere i sno single Spring container.Spring actually comes with two distince types of containers:Bean factories and Application

contexts.Beyong there two basic types of contains .Srping come with sereral implementss of BeanFacotory and ApplicationContext.
1 introducing the BeanFactory
There are several implementations of BeanFactory in Spring .But the most userful one is XmlBeanFactory,whick loads
its bean based on the definitions contained in an xml file.
Creat a XmlBeanFactory BeanFactory factory=new XMLBeanFactory(new FileInputStream("beans.xml"));
But at that time ,the BeanFactory does not initialize the bean ,it is loaded lazliy.
Get the Bean :MyBean myBean=(MyBean)factory.getBean("myBean");
When getBean() is called ,the factory will instantiate the bean and being setting the bean using dependency injection.
2 Working with an application context
an ApplicationContextis prefered over a BeanFactory in nearly all application ,the only time you might consider using a BeanFactory

are in circumtance where resource s are scarce.
   Amony the many implements of ApplicationContext are three that are commonly used:
      ClassPathXmlApplicationContext,FileSystemXmpApplicationContext,XmlWebApplicationContext.
   ApplicationContext context=new ClassPathXmlApplicationContext("foo.xml");
wiring the beans



Prototyping vs.singleton
By default ,all Spring beans are singletons.When the container dispenses a bean it will always give the exact same instance of the

In this case ,you would want to define a prototype bean .Defining a prototype means that instead of defining a single bean.
     on="false" />
Initialization and destruction

Injectiong dependencies via setter method

        Foo McFoo

Referencing other beans






Inner beans
                class="com.CourseWericeImpl">

                       class="com....." />


Wiring collections
    1Wiring lists and arrays java.util.List


                bar1



   2 Wiring set java.tuil.Set


                 bar1



   3 Wiring maps java.util.Map


        bar1

4 Wiring propertyies


            bar1
            bar2


5 Setting null values

   injecting dependencies via constructor


        42( )



            http://www.manning.com


            http://www.manning.com

��h�� 2006-09-04 11:10 发表评论

hibernate �ȝ��基础

��h�� — Fri, 18 Aug 2006 08:20:00 GMT

1 java �c�d��Q�           �?hibernate �c�d��       sql
java .lang.String       string               varchar
java.lang.String        text                 Text
int                     int                  INT
char                    character             char(1)
boolean                 boolean              bit
byte[]                  binary               blob
java.sql.Date           date                 Date
java.sql.Timestamp      timestamp            Timestamp (载数据库中如果插入�ؓnull�Q�数据库�pȝ��自动插入为当前�?
2 表述层－�Q�》业务逻辑层－》hibernate�Q�》database
3
Configuration config=new Configuration();
config.add(Customer.class);
sessionFactory=conf.buildSessionFactory();
Session session=sessionFactory.openSession();
Transaction tx;
try{
   tx=session.beginTransaction();
   tx.commit();
}catch(Exception e){
    if(tx!=null){
      tx.rollback();
    }
}finally{
    session.close();
}
4 数据库存取blob 对象
1
   InputStream in=this.getClass().getResourceAsStream("photo.gif");
   byte[] buffer=new byte[in.available()]'
   in.read(buffer);
   customer.setImage(buffer);
2 byte[] buffer=customer.get.getImage();
   File OutputStream fout=new fileOutStream("photo.gif");
   fout.write(buffer);
   fout.close();

��h�� 2006-08-18 16:20 发表评论

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jdbc-batch processing

jdbc-prepare sql

java 调用存储�q�程 转蝲

OpenSessionInViewFilter解决Web应用�E�序的问�?转自�Q�Potain 的BLOG

OpenSessionInView

OpenSessionInViewFilter解决Web应用�E�序的问�?

HibernateInterceptor和OpenSessionInViewInterceptor的问�?

解决�Ҏ��

Spring -transaction

spring -database

hibernate -�c�d��

spring --wiring binding

hibernate �ȝ��基础

java 调用存储�q�程转蝲