Spring加载classpath与classpath*的过程剖析

使用spring-boot 1.5.7 

在resource目录下创建i18n文件夹

使用spring的默认配置没有加载到文件

# INTERNATIONALIZATION (MessageSourceAutoConfiguration)
spring.messages.always-use-message-format=false # Set whether to always apply the MessageFormat rules, parsing even messages without arguments.
spring.messages.basename=messages # Comma-separated list of basenames, each following the ResourceBundle convention.
spring.messages.cache-seconds=-1 # Loaded resource bundle files cache expiration, in seconds. When set to -1, bundles are cached forever.
spring.messages.encoding=UTF-8 # Message bundles encoding.
spring.messages.fallback-to-system-locale=true # Set whether to fall back to the system Locale if no files for a specific Locale have been found.

在 MessageSourceAutoConfiguration中看到如下代码：

不是很明白classpath*是什么意思
PathMatchingResourcePatternResolver中的方法实现

    @Override
    public Resource[] getResources(String locationPattern) throws IOException {
        Assert.notNull(locationPattern, "Location pattern must not be null");
        if (locationPattern.startsWith(CLASSPATH_ALL_URL_PREFIX)) {
            // a class path resource (multiple resources for same name possible)
　　　　　　　// CLASSPATH_ALL_URL_PERFIX = "classpath*";　　　
　　　　　　　//getPathMatcher().isPattern("messages.properties") 返回false

            if (getPathMatcher().isPattern(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()))) {
                // a class path resource pattern
                return findPathMatchingResources(locationPattern);
            }
            else {
                // all class path resources with the given name
                return findAllClassPathResources(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()));
            }
        }
        else {
            // Generally only look for a pattern after a prefix here,
            // and on Tomcat only after the "*/" separator for its "war:" protocol.
            int prefixEnd = (locationPattern.startsWith("war:") ? locationPattern.indexOf("*/") + 1 :
                    locationPattern.indexOf(":") + 1);
            if (getPathMatcher().isPattern(locationPattern.substring(prefixEnd))) {
                // a file pattern
                return findPathMatchingResources(locationPattern);
            }
            else {
                // a single resource with the given name
                return new Resource[] {getResourceLoader().getResource(locationPattern)};
            }
        }
    }

解决方法：

    @Bean
    public MessageSource messageSource() {
        ReloadableResourceBundleMessageSource messageSource = new ReloadableResourceBundleMessageSource();
        messageSource.setBasename("classpath:i18n/messages");
        messageSource.setDefaultEncoding("UTF-8");
        return messageSource;
    }

ResourceBundleMessageSource限制了我们只能将对应的资源文件放置在类路径下

ReloadableResourceBundleMessageSource允许我们指定非类路径下的文件作为对应的资源文件