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[hyddd的FindBugs分析记录][M X OBL] Method may fail to clean up stream or resource

[M X OBL] Method may fail to clean up stream or resource [OBL_UNSATISFIED_OBLIGATION]

This method may fail to clean up (close, dispose of) a stream, database object, or other resource requiring an explicit cleanup operation.

In general, if a method opens a stream or other resource, the method should use a try/finally block to ensure that the stream or resource is cleaned up before the method returns.

This bug pattern is essentially the same as the OS_OPEN_STREAM and ODR_OPEN_DATABASE_RESOURCE bug patterns, but is based on a different (and hopefully better) static analysis technique. We are interested is getting feedback about the usefulness of this bug pattern. To send feedback, either:

• send email to [e-mail]
• file a bug report: http://findbugs.sourceforge.net/reportingBugs.html

In particular, the false-positive suppression heuristics for this bug pattern have not been extensively tuned, so reports about false positives are helpful to us.

See Weimer and Necula, Finding and Preventing Run-Time Error Handling Mistakes , for a description of the analysis technique.

 

这个BUG想说明的是：有些资源打开了，但在函数结束的时候却没有关闭。比如：数据库连接......

虽然JAVA有垃圾回收机制，但是，自己打开的资源需要自己手动关闭，否则有可能直到程序退出，JRE才会清理你打开的资源。这里FindBugs建议在try/finally里面关闭打开的资源，在关闭之前，还要判断资源是否为Null，或者再加一层异常捕获处理噢～

以下是一些可能关闭资源失败的例子：

-----------------------------------------------情况1-----------------------------------------

 

//
FileOutputStream fs  =   null ;
try {
　　fs  =   new  FileOutputStream(clearTableFile);
　　fs.close();     // 当出异常时候fs关闭失败，所以应该在finally中关闭
}
catch ( ){
//
}

-----------------------------------------------情况2-----------------------------------------

 

//
Properties props  =   new  Properties();
try{
　　props.store( new  FileOutputStream(configFile), configFile); 　　// new FileOutputStream(configFile)没有释放。
}
catch( ){
　　//
}

-----------------------------------------------情况3-----------------------------------------

 

　　//
　　FileOutputStream fs  =   new  FileOutputStream(clearTableFile);
　　//     (里没有做异常处理，如果中间出异常了，异常会抛往上层，这时fs就没能释放了。
　　fs.close();    
　　//

http://www.ibm.com/developerworks/cn/java/j-dyn0414/index.html

http://bcel.sourceforge.net/docs/index.html

http://findbugs.sourceforge.net/api/edu/umd/cs/findbugs/ba/BlockType.html

http://code.google.com/p/findbugs/wiki/DetectorPluginTutorial

http://www.ibm.com/developerworks/java/library/j-findbug1/#resources