阅读本文大概需要 5 分钟。
来自：http://ww7.rowkey.me/
在Finally块中清理资源或者使用try-with-resource语句
public void doNotCloseResourceInTry() {
FileInputStream inputStream = null;
try {
File file = new File("./tmp.txt");
inputStream = new FileInputStream(file);
// use the inputStream to read a file
// do NOT do this
inputStream.close();
} catch (FileNotFoundException e) {
log.error(e);
} catch (IOException e) {
log.error(e);
}
}
public void closeResourceInFinally() {
FileInputStream inputStream = null;
try {
File file = new File("./tmp.txt");
inputStream = new FileInputStream(file);
// use the inputStream to read a file
} catch (FileNotFoundException e) {
log.error(e);
} finally {
if (inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
log.error(e);
}
}
}
}
public void automaticallyCloseResource() {
File file = new File("./tmp.txt");
try (FileInputStream inputStream = new FileInputStream(file);) {
// use the inputStream to read a file
} catch (FileNotFoundException e) {
log.error(e);
} catch (IOException e) {
log.error(e);
}
}
指定具体的异常
public void doNotDoThis() throws Exception {
...
}
public void doThis() throws NumberFormatException {
...
}
对异常进行文档说明
/**
* This method does something extremely useful ...
*
* @param input
* @throws MyBusinessException if ... happens
*/
public void doSomething(String input) throws MyBusinessException {
...
}
抛出异常的时候包含描述信息
try {
new Long("xyz");
} catch (NumberFormatException e) {
log.error(e);
}
首先捕获最具体的异常
public void catchMostSpecificExceptionFirst() {
try {
doSomething("A message");
} catch (NumberFormatException e) {
log.error(e);
} catch (IllegalArgumentException e) {
log.error(e)
}
}
# 不要捕获Throwable
public void doNotCatchThrowable() {
try {
// do something
} catch (Throwable t) {
// don't do this!
}
}
不要忽略异常
public void doNotIgnoreExceptions() {
try {
// do something
} catch (NumberFormatException e) {
// this will never happen
}
}
public void logAnException() {
try {
// do something
} catch (NumberFormatException e) {
log.error("This should never happen: " + e);
}
}
不要记录并抛出异常
try {
new Long("xyz");
} catch (NumberFormatException e) {
log.error(e);
throw e;
}
17:44:28,945 ERROR TestExceptionHandling:65 - java.lang.NumberFormatException: For input string: "xyz"
Exception in thread "main" java.lang.NumberFormatException: For input string: "xyz"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Long.parseLong(Long.java:589)
at java.lang.Long.(Long.java:965)
at com.stackify.example.TestExceptionHandling.logAndThrowException(TestExceptionHandling.java:63)
at com.stackify.example.TestExceptionHandling.main(TestExceptionHandling.java:58)
如上所示，后面的日志也没有附加更有用的信息。如果想要提供更加有用的信息，
那么可以将异常包装为自定义异常。
public void wrapException(String input) throws MyBusinessException {
try {
// do something
} catch (NumberFormatException e) {
throw new MyBusinessException("A message that describes the error.", e);
}
}
包装异常时不要抛弃原始的异常
public void wrapException(String input) throws MyBusinessException {
try {
// do something
} catch (NumberFormatException e) {
throw new MyBusinessException("A message that describes the error.", e);
}
}
总结
个人博客网站：https://programmerblog.xyz
本文分享自微信公众号 - IT技术分享社区（gh_a27c0758eb03）。
如有侵权，请联系 [email protected] 删除。
本文参与“OSC源创计划”，欢迎正在阅读的你也加入，一起分享。