使用 hibernate 从 oracle 读取 clob
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read a clob from oracle using hibernate
提问by JSixface
I am having a big headache in finding out what is the problem here ..
我在找出这里的问题时很头疼..
I get a session from the session factory and then get the clob out of the persistant object. When it comes to clob.getCharcterStream() or getAsciiStream(), it throws an exception - Closed connection.
我从会话工厂获得一个会话，然后从持久对象中取出 clob。当涉及到 clob.getCharcterStream() 或 getAsciiStream() 时，它会抛出异常 - 关闭连接。
Can someone help me with this.
有人可以帮我弄这个吗。
code :
代码 ：
Session session = Dao.getSession(connId);
Package pack = (Package) session.load(Package.class, packId);
Hibernate.initialize(pack);
Clob reportClob = pack.getExpReportFile();
String result = null;
InputStream stream = null;
try
{
System.out.println(session.isConnected() + " " + session.isOpen());
stream = reportClob.getAsciiStream();
result = IOUtils.toString(stream);
}
catch (SQLException e)
{
e.printStackTrace();
}
return result;
Exception :
例外 ：
true true
java.sql.SQLException: Closed Connection
at oracle.sql.CLOB.getDBAccess(CLOB.java:1389)
at oracle.sql.CLOB.getAsciiStream(CLOB.java:330)
at org.hibernate.lob.SerializableClob.getAsciiStream(SerializableClob.java:68)
at com.server.WebServiceImpl.fetchPackageReport(WebServiceImpl.java:2070)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:562)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:188)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:224)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
回答by ayush
The reason for this error is that the session that your entity is attached to is now closed.
此错误的原因是您的实体附加到的会话现已关闭。
try db connection with autocommit turned off(hibernate.connection.autocommit) or you need an open transaction.
尝试关闭自动提交的数据库连接(hibernate.connection.autocommit）或者您需要一个打开的事务。
回答by Thomas
Is there a specific reason that you need it to be a Clob? Looking at the sample code, it looks like you are putting it into a String, and Hibernate supports putting Clobs into String, char[]and Clob. This should fix the problem.
是否有特定原因需要它成为 Clob？看样例代码，好像是把它放到一个String里面，Hibernate支持把Clob放到String,char[]和Clob. 这应该可以解决问题。
If a requirement is to only have ASCII characters in the string, you can always do something like:
如果要求字符串中只包含 ASCII 字符，您总是可以执行以下操作：
String ascii = new String(oldString.getBytes("ASCII"),"ASCII");
Warning: if you change to using Stringyou might run into this bug, however it is still worth a try.
警告：如果您更改为使用，String您可能会遇到此错误，但仍然值得一试。
回答by Swen Thümmler
You might try adding the system property hibernate.jdbc.use_streams_for_binary=true (this fixed the closed connection errors for me)
您可以尝试添加系统属性 hibernate.jdbc.use_streams_for_binary=true （这为我修复了关闭的连接错误）
