语源科技BlogJava-Java Programing Language

NonUniqueObjectException

bill — Thu, 25 Sep 2008 09:07:00 GMT

org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session

首先看看这个类：
//$Id: NonUniqueObjectException.java,v 1.4 2005/02/12 07:19:50 steveebersole Exp $
2 package org.hibernate;
3
4 import java.io.Serializable ;
5
6 import org.hibernate.pretty.MessageHelper;
7
8 /**
9 * This exception is thrown when an operation would
10 * break session-scoped identity. This occurs if the
11 * user tries to associate two different instances of
12 * the same Java class with a particular identifier,
13 * in the scope of a single Session.
14 *
15 * @author Gavin King
16 */
17 public class NonUniqueObjectException extends HibernateException {
18     private final Serializable identifier;
19     private final String entityName;
20
21     public NonUniqueObjectException(String message, Serializable id, String clazz) {
22         super(message);
23         this.entityName = clazz;
24         this.identifier = id;
25     }
26
27     public NonUniqueObjectException(Serializable id, String clazz) {
28         this("a different object with the same identifier value was already associated with the session", id, clazz);
29     }
30
31     public Serializable getIdentifier() {
32         return identifier;
33     }
34
35     public String getMessage() {
36         return super.getMessage() + ": " +
37             MessageHelper.infoString(entityName, identifier);
38     }
39
40     public String getEntityName() {
41         return entityName;
42     }
43
44 }

解决方案：
     this..getSession().clear();

bill 2008-09-25 17:07 发表评论

SSH整合中的问题

bill — Tue, 09 Sep 2008 13:36:00 GMT

Error Creating SessionFactory java.lang.SecurityException: class"org.apache.commons.collections.SequencedHashMap"'异常的解决方案

本人用 MyEclipse 6.0.0 开发 Struts + Hibernate应用的时候，单独测试Hibernate的类没有问题，但是当Web层和Struts整合后，就抛出如下异常：
%%%%Error Creating SessionFactory %%%% java.lang.SecurityException: class"org.apache.commons.collections.SequencedHashMap"'s signer informationdoes not match signer information of other classes in the same package

   原因是myeclipse 6.0的jar包问题。这个是myeclipse没有做好严格的测试。

   网上好多人说是commons-collectionsXXX.jar的问题。我也不知道。我是把所有的myeclipse生成的jar都remove buildpath 了。
   我又自己添加的jar。就OK！！！！

bill 2008-09-09 21:36 发表评论

sql server 2000 安装挂起问题

bill — Sat, 06 Sep 2008 17:32:00 GMT

sql server 2000 安装挂起问题：

解决方案：开始--->运行--->regedit--->HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager

删除PendingFileRenameOperations

bill 2008-09-07 01:32 发表评论

JAVA 连接MYSQL

bill — Sat, 29 Dec 2007 14:38:00 GMT

今天我给大家介绍一下JAVA 连接 MYSQL:
我都不教你怎么装MYSQL了，网上我看了很多要下载JDBC我也下载了，和配置了CLASSPATH 但是还是不能用。后来我发现不需要配置了。直接COPY mysql-connector-java-5.0.7-bin.jar到
D:\Program Files\Java\jdk1.6.0_02\jre\lib\ext\mysql-connector-java-5.0.7-bin.jar
所以，我希望连接的大家不要走弯路。
这是我写的程序：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class test {
public static void main(String[] args) {
try {
Class.forName("org.gjt.mm.mysql.Driver").newInstance();
String url ="jdbc:mysql://localhost/demo?user=root&password=billsxm" ;
// demo is datebase name
Connection conn= DriverManager.getConnection(url);
Statement stmt=conn.createStatement();
String sql="select * from my_table";
ResultSet rs=stmt.executeQuery(sql);
while(rs.next()) {
System.out.println(rs.getString("name"));
}
} catch (Exception e) {
e.printStackTrace();
}

}
}

bill 2007-12-29 22:38 发表评论