db2 的 ExceptionInInitializerError

发布于 2024-11-09 03:54:29 字数 1163 浏览 0 评论 0原文

我有最简单的 JDBC 程序来从 DB2（或其他配置的）实例读取数据。当我尝试从 Eclipse 或从命令行运行它时，连接失败，抛出 SQL 异常

 Class.forName(jdbcDriverClassName).newInstance();

class.forName 失败，使用 com.ibm.db2.jcc.DB2Driver。我将 Eclipse 配置为指向 DBVisualizer 使用的同一驱动程序（既作为启动库又用于项目）。该程序使用与 DBVisualizer 相同的连接字符串。 DBVisualizer 没有任何问题。

带完整堆栈的输出（请注意驱动程序的 FQN 不为空）：

                   V-- !null driver name --V
Attempting to load com.ibm.db2.jcc.DB2Driver
ERROR:java.lang.ExceptionInInitializerError: null
java.lang.ExceptionInInitializerError
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at com.ibm.db2.jcc.DB2Driver.class$(DB2Driver.java:58)
at com.ibm.db2.jcc.DB2Driver.<clinit>(DB2Driver.java:61)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at com.onlineretailer.ecomm.dumporder.DumpOrder.main(DumpOrder.java:79)
Caused by: java.lang.NullPointerException
at com.ibm.db2.jcc.am.ib.i(ib.java:490)
at com.ibm.db2.jcc.am.ib.<clinit>(ib.java:420)
... 7 more

我还尝试将 .newInstance() 添加到 class.forName() 的末尾，并且它继续执行相同的行为。

感谢大家的时间和投入！

原文

I have the simplest JDBC program to read data from a DB2 (or other configured) instance. When I attempt to run it from Eclipse OR from the command line, the connect fails, throwing a SQLexception

 Class.forName(jdbcDriverClassName).newInstance();

The class.forName fails, using com.ibm.db2.jcc.DB2Driver. I configured Eclipse to point to the same driver that DBVisualizer uses (both as a boot library and for the project). The program uses the same connect string that DBVisualizer uses. DBVisualizer isn't having any trouble.

Ouptut w/full stack (note the FQN for the driver is not null):

                   V-- !null driver name --V
Attempting to load com.ibm.db2.jcc.DB2Driver
ERROR:java.lang.ExceptionInInitializerError: null
java.lang.ExceptionInInitializerError
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at com.ibm.db2.jcc.DB2Driver.class$(DB2Driver.java:58)
at com.ibm.db2.jcc.DB2Driver.<clinit>(DB2Driver.java:61)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at com.onlineretailer.ecomm.dumporder.DumpOrder.main(DumpOrder.java:79)
Caused by: java.lang.NullPointerException
at com.ibm.db2.jcc.am.ib.i(ib.java:490)
at com.ibm.db2.jcc.am.ib.<clinit>(ib.java:420)
... 7 more

I also tried adding the .newInstance() to the end of the class.forName() and it continues to execute the same behavior.

Thanks to everyone for your time and input!

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望喜 2024-11-16 03:54:29

SQLException：没有找到适合 jdbc:db2:... 的驱动程序

此异常只有 2 个可能的原因：

JDBC 驱动程序未知，DriverManager。即 JDBC 驱动程序未通过 DriverManager#registerDriver()。
对于使用 DriverManager 注册的任何 JDBC 驱动程序，JDBC URL 都是未知的。即 Driver#acceptsURL() 尚未为任何已注册的驱动程序返回 true。

您的 JDBC 驱动程序类名完全没问题。您的 JDBC URL 完全没问题。

精心设计的 JDBC 驱动程序会在 static {} 初始化块中向 DriverManager 注册自身，该初始化块在 Class#forName()< 上执行/代码>。但是，旧版本的 IBM DB2 JDBC 驱动程序将其自身注册到构造函数中。对于那些损坏的驱动程序，您需要调用 newInstance() 之后也是如此。

Class.forName("com.ibm.db2.jcc.DB2Driver").newInstance();

另请参阅：

更新根据您的问题更新，newInstance()做到了这个技巧。然而，它导致了一个新问题：

Caused by: java.lang.NullPointerException
at com.ibm.db2.jcc.am.ib.i(ib.java:490)
at com.ibm.db2.jcc.am.ib.<clinit>(ib.java:420)

事实证明这是 DB2 JDBC 驱动程序本身的另一个错误。升级它。

SQLException: No suitable driver found for jdbc:db2:...

This exception has only 2 possible causes:

The JDBC driver is unknown with DriverManager. I.e. the JDBC driver has not registered itself properly by DriverManager#registerDriver().
The JDBC URL is unknown for any of the JDBC drivers registered with DriverManager. I.e. the Driver#acceptsURL() hasn't returned true for any of the registered drivers.

Your JDBC driver class name is perfectly fine. Your JDBC URL is perfectly fine.

A well designed JDBC driver registers itself with DriverManager in a static {} initializer block which get executed upon Class#forName(). However, older versions of the IBM DB2 JDBC driver registers itself in the constructor instead. For those broken drivers you need to call newInstance() afterwards as well.

Class.forName("com.ibm.db2.jcc.DB2Driver").newInstance();

String databaseURL = "jdbc:derby:net://localhost:1527/sample";
// Load DB2 Driver for JDBC class
Class.forName("com.ibm.db2.jcc.DB2Driver");
// Set user and password properties
Properties properties = new Properties();
properties.put("user", "APP");
properties.put("password", "APP");
properties.put("retreiveMessagesFromServerOnGetMessage", "true");
// Get a connection
Connection conn = DriverManager.getConnection(databaseURL, properties);

参考

用于 JDBC 的 DB2 驱动程序示例

You need to load driver too in your jvm , using Class.forName()
You need to load following driver

com.ibm.db2.jcc.DB2Driver

Here is how it fully look like

String databaseURL = "jdbc:derby:net://localhost:1527/sample";
// Load DB2 Driver for JDBC class
Class.forName("com.ibm.db2.jcc.DB2Driver");
// Set user and password properties
Properties properties = new Properties();
properties.put("user", "APP");
properties.put("password", "APP");
properties.put("retreiveMessagesFromServerOnGetMessage", "true");
// Get a connection
Connection conn = DriverManager.getConnection(databaseURL, properties);

Reference