之前在项目中一直使用FileSystemResource这个类作为PropertyPlaceholderConfigurer的Resource引入部署目录外的配置文件，并设置了setIgnoreResourceNotFound为true，最近把Spring Framework升级为5.0.2，当外部配置文件不存在时，PropertyPlaceholderConfigurer的初始化会报错，貌似setIgnoreResourceNotFound不再起作用，今天看了一下源码
先看PropertyPlaceholderConfigurer的父类PlaceholderConfigurerSupport中的一段：
/**
* Load properties into the given instance.
* @param props the Properties instance to load into
* @throws IOException in case of I/O errors
* @see #setLocations
*/
protected void loadProperties(Properties props) throws IOException {
if (this.locations != null) {
for (Resource location : this.locations) {
if (logger.isDebugEnabled()) {
logger.debug("Loading properties file from " + location);
}
try {
PropertiesLoaderUtils.fillProperties(
props, new EncodedResource(location, this.fileEncoding), this.propertiesPersister);
}
catch (IOException ex) {
// Resource not found when trying to open it
if (this.ignoreResourceNotFound &&
(ex instanceof FileNotFoundException || ex instanceof UnknownHostException)) {
if (logger.isInfoEnabled()) {
logger.info("Properties resource not found: " + ex.getMessage());
}
}
else {
throw ex;
}
}
}
}
}
得知，在设置了ignoreResourceNotFound之后，Resource类抛出的异常必须是FileNotFoundException才能生效，但是在Spring Framework 5中FileSystemResource已经换用nio下面的包来实现了，抛出的也是nio包下面的异常java.nio.file.NoSuchFileException，所以ignoreResourceNotFound不再有效，从FileSystemResource的说明中得知还有PathResource这个类，就换它试了一下，问题解决。
