1.1 ResourcePatternResolver
ResourceLoader 的 Resource getResource(String location),每次只能根据 location 返回一个 Resource 。
ResourcePatternResolver 是 ResourceLoader 的扩展,它支持根据指定的资源路径匹配模式每次返回多个 Resource 实例
org.springframework.core.io.support;
public interface ResourcePatternResolver extends ResourceLoader {
String CLASSPATH_ALL_URL_PREFIX = "classpath*:";
Resource[] getResources(String locationPattern) throws IOException;
}
1.2 PathMatchingResourcePatternResolver
ResourcePatternResolver 最常用的子类
支持 ResourceLoader 和 ResourcePatternResolver 新增的 "classpath*:" 通配符前缀外,还支持 Ant风格的路径匹配模式(Ant风格类似于 "**/*.xml")
org.springframework.core.io.support;
public class PathMatchingResourcePatternResolver implements ResourcePatternResolver {
private final ResourceLoader resourceLoader;
private PathMatcher pathMatcher = new AntPathMatcher();
public PathMatchingResourcePatternResolver() {
this.resourceLoader = new DefaultResourceLoader();
}
public PathMatchingResourcePatternResolver(ResourceLoader resourceLoader) {
Assert.notNull(resourceLoader, "ResourceLoader must not be null");
this.resourceLoader = resourceLoader;
}
public PathMatchingResourcePatternResolver(@Nullable ClassLoader classLoader) {
this.resourceLoader = new DefaultResourceLoader(classLoader);
}
@Override
public Resource getResource(String location) {
return getResourceLoader().getResource(location);
}
@Override
public Resource[] getResources(String locationPattern) throws IOException {
Assert.notNull(locationPattern, "Location pattern must not be null");
if (locationPattern.startsWith(CLASSPATH_ALL_URL_PREFIX)) {
if (getPathMatcher().isPattern(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()))) {
return findPathMatchingResources(locationPattern);
}
else {
return findAllClassPathResources(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()));
}
}
else {
int prefixEnd = (locationPattern.startsWith("war:") ? locationPattern.indexOf("*/") + 1 :
locationPattern.indexOf(':') + 1);
if (getPathMatcher().isPattern(locationPattern.substring(prefixEnd))) {
return findPathMatchingResources(locationPattern);
}
else {
return new Resource[] {getResourceLoader().getResource(locationPattern)};
}
}
}
}
1.3 findPathMatchingResources
当 locationPattern 中包含了通配符,则调用该方法进行资源加载
protected Resource[] findPathMatchingResources(String locationPattern) throws IOException {
String rootDirPath = determineRootDir(locationPattern);
String subPattern = locationPattern.substring(rootDirPath.length());
Resource[] rootDirResources = getResources(rootDirPath);
Set<Resource> result = new LinkedHashSet<>(16);
for (Resource rootDirResource : rootDirResources) {
rootDirResource = resolveRootDirResource(rootDirResource);
URL rootDirUrl = rootDirResource.getURL();
if (equinoxResolveMethod != null && rootDirUrl.getProtocol().startsWith("bundle")) {
URL resolvedUrl = (URL) ReflectionUtils.invokeMethod(equinoxResolveMethod, null, rootDirUrl);
if (resolvedUrl != null) {
rootDirUrl = resolvedUrl;
}
rootDirResource = new UrlResource(rootDirUrl);
}
if (rootDirUrl.getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
result.addAll(VfsResourceMatchingDelegate.findMatchingResources(rootDirUrl, subPattern, getPathMatcher()));
}
else if (ResourceUtils.isJarURL(rootDirUrl) || isJarResource(rootDirResource)) {
result.addAll(doFindPathMatchingJarResources(rootDirResource, rootDirUrl, subPattern));
}
else {
result.addAll(doFindPathMatchingFileResources(rootDirResource, subPattern));
}
}
if (logger.isTraceEnabled()) {
logger.trace("Resolved location pattern [" + locationPattern + "] to resources " + result);
}
return result.toArray(new Resource[0]);
}
1.4 findAllClassPathResources
locationPattern 以 "classpath*:" 开头但是不包含通配符,则调用此方法
protected Resource[] findAllClassPathResources(String location) throws IOException {
String path = location;
if (path.startsWith("/")) {
path = path.substring(1);
}
Set<Resource> result = doFindAllClassPathResources(path);
if (logger.isTraceEnabled()) {
logger.trace("Resolved classpath location [" + location + "] to resources " + result);
}
return result.toArray(new Resource[0]);
}
doFindAllClassPathResources方法 (真正执行加载的方法)
protected Set<Resource> doFindAllClassPathResources(String path) throws IOException {
Set<Resource> result = new LinkedHashSet<>(16);
ClassLoader cl = getClassLoader();
Enumeration<URL> resourceUrls = (cl != null ? cl.getResources(path) : ClassLoader.getSystemResources(path));
while (resourceUrls.hasMoreElements()) {
URL url = resourceUrls.nextElement();
result.add(convertClassLoaderURL(url));
}
if ("".equals(path)) {
addAllClassLoaderJarRoots(cl, result);
}
return result;
}