NonUniqueObjectException

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

首先看看這個類：
//$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 <tt>Session</tt>.
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 }


解決方案：
     this..getSession().clear();

posted @ 2008-09-25 17:07 bill 閱讀(902) | 評論 (0) | 編輯 收藏

SSH整合中的問題

Error Creating SessionFactory java.lang.SecurityException: class"org.apache.commons.collections.SequencedHashMap"'異常的解決方案

本人用 MyEclipse 6.0.0 開發 Struts + Hibernate應用的時候，單獨測試Hibernate的類沒有問題，但是當Web層和Struts整合后，就拋出如下異常：
%%%%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包問題。這個是myeclipse沒有做好嚴格的測試。

   網上好多人說是commons-collectionsXXX.jar的問題。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！！！！

posted @ 2008-09-09 21:36 bill 閱讀(233) | 評論 (0) | 編輯 收藏

sql server 2000 安裝掛起問題

   sql server 2000 安裝掛起問題：

posted @ 2008-09-07 01:32 bill 閱讀(238) | 評論 (0) | 編輯 收藏

JAVA 連接MYSQL

今天我給大家介紹一下JAVA 連接 MYSQL:
     我都不教你怎么裝MYSQL了，網上我看了很多要下載JDBC我也下載了，和配置了CLASSPATH 但是還是不能用。后來我發現不需要配置了。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，我希望連接的大家不要走彎路。
 這是我寫的程序：

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();
}

}
}

posted @ 2007-12-29 22:38 bill 閱讀(3628) | 評論 (3) | 編輯 收藏