在Sprng当中如何加载多个配置文件

Question

第一种:

使用一个数组,将所有要加载的配置文件放入到数组当中

Java代码

ApplicationContext ctx = new ClassPathXmlApplicationContext(new String[]{"a.xml","b.xml"});

第二种:

使用通配符,这种方法不知道对于不在同一个路径下的配置起不起作用,本人没试验过!

Java代码

ApplicationContext ctx = new ClassPathXmlApplicationContext("classpath:/*.xml");

spring的源码是如何实现同时加载两个以上的配置文件的？

我的意思是源码在何处判断是否有两个路径，以及怎么去加载。

最好能贴上源代码。困惑了很久，请高手解决，不胜感激。

Answer 1

1、你疑惑的是classpath 加载方式
2、那就分析ClassPathXmlApplicationContext
*/
[url] public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh, ApplicationContext parent)
throws BeansException {

    super(parent);
    setConfigLocations(configLocations);
    if (refresh) {
        refresh();
    }
}[/url]

调用了setConfigLocations(configLocations);设置路径

public void setConfigLocations(String[] locations) {
if (locations != null) {
Assert.noNullElements(locations, "Config locations must not be null");
this.configLocations = new String[locations.length];
for (int i = 0; i < locations.length; i++) {
this.configLocations[i] = resolvePath(locations[i]).trim();
}
}
else {
this.configLocations = null;
}
}

resolvePath用于替换${} 占位符

这样就能解析出configLocations

3、接下来加载bean
[quote] protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException {
Resource[] configResources = getConfigResources();
if (configResources != null) {
reader.loadBeanDefinitions(configResources);
}
String[] configLocations = getConfigLocations();
if (configLocations != null) {
reader.loadBeanDefinitions(configLocations);
}
}[/quote]

[quote] public int loadBeanDefinitions(String... locations) throws BeanDefinitionStoreException {
Assert.notNull(locations, "Location array must not be null");
int counter = 0;
for (String location : locations) {
counter += loadBeanDefinitions(location);
}
return counter;
}
[/quote]

到了重点
[quote]public int loadBeanDefinitions(String location, Set actualResources) throws BeanDefinitionStoreException {
ResourceLoader resourceLoader = getResourceLoader();
if (resourceLoader == null) {
throw new BeanDefinitionStoreException(
"Cannot import bean definitions from location [" + location + "]: no ResourceLoader available");
}

    if (resourceLoader instanceof ResourcePatternResolver) {
        // Resource pattern matching available.
        try {
            Resource[] resources = ((ResourcePatternResolver) resourceLoader).getResources(location);
            int loadCount = loadBeanDefinitions(resources);
            if (actualResources != null) {
                for (Resource resource : resources) {
                    actualResources.add(resource);
                }
            }
            if (logger.isDebugEnabled()) {
                logger.debug("Loaded " + loadCount + " bean definitions from location pattern [" + location + "]");
            }
            return loadCount;
        }
        catch (IOException ex) {
            throw new BeanDefinitionStoreException(
                    "Could not resolve bean definition resource pattern [" + location + "]", ex);
        }
    }
    else {
        // Can only load single resources by absolute URL.
        Resource resource = resourceLoader.getResource(location);
        int loadCount = loadBeanDefinitions(resource);
        if (actualResources != null) {
            actualResources.add(resource);
        }
        if (logger.isDebugEnabled()) {
            logger.debug("Loaded " + loadCount + " bean definitions from location [" + location + "]");
        }
        return loadCount;
    }
}[/quote]

3.1、重点
3.1.1、getResourceLoader() --->
在AbstractXmlApplicationContext（ClasspathXmlApplicationContext（继承它） beanDefinitionReader.setResourceLoader(this); 即ClasspathXmlApplicationContext本身 通过观察你会发现是DefaultResourceLoader

它的解释：根据不同的前缀返回不同的Resource （到此其实就把你的疑问差不多解决了）

• Will return a {@link UrlResource} if the location value is a URL,

  • and a {@link ClassPathResource} if it is a non-URL path or a
  • "classpath:" pseudo-URL.

3.1.2、模式字符串的加载
if (resourceLoader instanceof ResourcePatternResolver) {
// Resource pattern matching available.
try {
Resource[] resources = ((ResourcePatternResolver) resourceLoader).getResources(location);

如果是模式 能找到多个--继续找下去 //classpath:aa*
for (Resource resource : resources) {

actualResources.add(resource);
}

其实你现在再去看下ClasspathResource就可以了

具体使用可以参考
[url]http://jinnianshilongnian.iteye.com/blog/1416322[/url]