Database activemq-data\localhost\KahaDB\lock is locked...

Posted 2023-03-21

Database activemq-data\localhost\KahaDB\lock is locked... waiting 10 seconds for the database to be unlocked. Reason: java.io.IOException: File 'activemq-data\localhost\KahaDB\lock' could not be locked.
这个是jms+activemq 做的。
在java中运行第二次就报这个错，哪位高手帮我解答一下。谢了

参考技术A 因为你安装activemq服务默认是随系统启动的，所以你一开机activemq服务器就启动了，启动后就锁定了activemq的数据库，所以如果你再次启动的话就会报数据库被锁定的错误

解决办法一：停止activemq服务，再手动启动(多次一举，因为本来就启动了)

解决办法二：配置activemq服务为手动启动，这样activemq服务就不会随系统启动了，每次要自己启动activemq服务 参考技术B 卸载服务（UninstallService.bat），然后重新运行就可以了。

Database Security: Database Vulnerability

Security breaches are an increasing phenomenon.

As more and more databases are made accessible via the Internet and web-based applications, their exposure to security threats will rise.

The objective is to reduce susceptibility to these threats.

Perhaps the most publicized database application vulnerability has been the SQL injection.

SQL injections provide excellent examples for discussing security as they embody one of the most important database security issues, risks inherent to non-validated user input.

SQL injections can happen when SQL statements are dynamically created using user input.

The threat occurs when users enter malicious code that ‘tricks’ the database into executing unintended commands.

The vulnerability occurs primarily because of the features of the SQL language that allow such things as embedding comments using double hyphens (- -), concatenating SQL statements separated by semicolons, and the ability to query metadata from database data dictionaries.

The solution to stopping an SQL injection is input validation.

SQL injections can be prevented by validating user input.

Three approaches are commonly used to address query string validation: using a black list, using a white list, or implementing parameterized queries.

The black list parses the input string comparing each character to a predefined list of non-allowed characters. The disadvantage to using a black list is that many special characters can be legitimate but will be rejected using this approach. The common example is the use of the apostrophe in a last name such as O’Hare.

The white list approach is similar except that each character is compared to a list of allowable characters. The approach is preferred but special considerations have to be made when validating the single quote.

Parameterized queries use internally defined parameters to fill in a previously prepared SQL statement.

The importance of input validation cannot be overstated. It is one of the primary defense mechanisms for preventing database vulnerabilities including SQL injections.