1、XmlBeanFactory 的使用，参考MyEclipse Spring 学习总结一 Spring IOC容器
public static void main(String[] args) {
XmlBeanFactory factory = new XmlBeanFactory(new ClassPathResource("applicationContext.xml"));
HelloWorld obj = (HelloWorld)factory.getBean("helloWorld");
obj.getMessage();
}
2、使用DefaultListableBeanFactory和XmlBeanDefinitionReader
ClassPathResource resource = new ClassPathSource("beans.xml");
DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(factory);
reader.loadBeanDefinitions(resource);
Spring加载资源并装配对象的过程
1、定义好Spring的配置文件
2、通过Resource将Spring配置文件进行抽象，抽象成一个Resource对象
3、定义好Bean工厂（各种BeanFactory）
4、定义好XmlBeanDefinitionReader对象，并将工厂对象作为参数传递进去供后续回调使用。
5、通过XmlBeanDefinitionReader对象读取之前抽象出的Resource对象（包含了XML文件的解析过程）
6、本质上，XML文件的解析是有XmlBeanDefinitionReader对象交由BeanDefinitionParserDelegate委托来完成的。实质上这里使用到类委托模式。
7、Ioc容器创建完毕，用户可以通过容器获取所需的对象信息。
3、查看ClassPathResource
首先查看InputStreamSource接口，里面定义了一个getInputStream方法
public interface InputStreamSource {
/**
* Return an {@link InputStream}.
* <p>It is expected that each call creates a <i>fresh</i> stream.
* <p>This requirement is particularly important when you consider an API such
* as JavaMail, which needs to be able to read the stream multiple times when
* creating mail attachments. For such a use case, it is <i>required</i>
* that each <code>getInputStream()</code> call returns a fresh stream.
* @throws IOException if the stream could not be opened
* @see org.springframework.mail.javamail.MimeMessageHelper#addAttachment(String, InputStreamSource)
*/
InputStream getInputStream() throws IOException;
}
然后查看Resource接口
public interface Resource extends InputStreamSource { /** * Return whether this resource actually exists in physical form. * <p>This method performs a definitive existence check, whereas the * existence of a <code>Resource</code> handle only guarantees a * valid descriptor handle. */ boolean exists(); /** * Return whether the contents of this resource can be read, * e.g. via {@link #getInputStream()} or {@link #getFile()}. * <p>Will be <code>true</code> for typical resource descriptors; * note that actual content reading may still fail when attempted. * However, a value of <code>false</code> is a definitive indication * that the resource content cannot be read. * @see #getInputStream() */ boolean isReadable(); /** * Return whether this resource represents a handle with an open * stream. If true, the InputStream cannot be read multiple times, * and must be read and closed to avoid resource leaks. * <p>Will be <code>false</code> for typical resource descriptors. */ boolean isOpen(); /** * Return a URL handle for this resource. * @throws IOException if the resource cannot be resolved as URL, * i.e. if the resource is not available as descriptor */ URL getURL() throws IOException; /** * Return a URI handle for this resource. * @throws IOException if the resource cannot be resolved as URI, * i.e. if the resource is not available as descriptor */ URI getURI() throws IOException; /** * Return a File handle for this resource. * @throws IOException if the resource cannot be resolved as absolute * file path, i.e. if the resource is not available in a file system */ File getFile() throws IOException; /** * Determine the content length for this resource. * @throws IOException if the resource cannot be resolved * (in the file system or as some other known physical resource type) */ long contentLength() throws IOException; /** * Determine the last-modified timestamp for this resource. * @throws IOException if the resource cannot be resolved * (in the file system or as some other known physical resource type) */ long lastModified() throws IOException; /** * Create a resource relative to this resource. * @param relativePath the relative path (relative to this resource) * @return the resource handle for the relative resource * @throws IOException if the relative resource cannot be determined */ Resource createRelative(String relativePath) throws IOException; /** * Determine a filename for this resource, i.e. typically the last * part of the path: for example, "myfile.txt". * <p>Returns <code>null</code> if this type of resource does not * have a filename. */ String getFilename(); /** * Return a description for this resource, * to be used for error output when working with the resource. * <p>Implementations are also encouraged to return this value * from their <code>toString</code> method. * @see java.lang.Object#toString() */ String getDescription(); /** * {@inheritDoc} * @return the input stream for the underlying resource (must not be {@code null}). */ public InputStream getInputStream() throws IOException; }
4、ClassPathResource 源码
public class ClassPathResource extends AbstractFileResolvingResource { private final String path; private ClassLoader classLoader; private Class<?> clazz; /** * Create a new ClassPathResource for ClassLoader usage. * A leading slash will be removed, as the ClassLoader * resource access methods will not accept it. * <p>The thread context class loader will be used for * loading the resource. * @param path the absolute path within the class path * @see java.lang.ClassLoader#getResourceAsStream(String) * @see org.springframework.util.ClassUtils#getDefaultClassLoader() */ public ClassPathResource(String path) { this(path, (ClassLoader) null); } /** * Create a new ClassPathResource for ClassLoader usage. * A leading slash will be removed, as the ClassLoader * resource access methods will not accept it. * @param path the absolute path within the classpath * @param classLoader the class loader to load the resource with, * or <code>null</code> for the thread context class loader * @see java.lang.ClassLoader#getResourceAsStream(String) */ public ClassPathResource(String path, ClassLoader classLoader) { Assert.notNull(path, "Path must not be null"); String pathToUse = StringUtils.cleanPath(path); if (pathToUse.startsWith("/")) { pathToUse = pathToUse.substring(1); } this.path = pathToUse; this.classLoader = (classLoader != null ? classLoader : ClassUtils.getDefaultClassLoader()); } /** * Create a new ClassPathResource for Class usage. * The path can be relative to the given class, * or absolute within the classpath via a leading slash. * @param path relative or absolute path within the class path * @param clazz the class to load resources with * @see java.lang.Class#getResourceAsStream */ public ClassPathResource(String path, Class<?> clazz) { Assert.notNull(path, "Path must not be null"); this.path = StringUtils.cleanPath(path); this.clazz = clazz; } /** * Create a new ClassPathResource with optional ClassLoader and Class. * Only for internal usage. * @param path relative or absolute path within the classpath * @param classLoader the class loader to load the resource with, if any * @param clazz the class to load resources with, if any */ protected ClassPathResource(String path, ClassLoader classLoader, Class<?> clazz) { this.path = StringUtils.cleanPath(path); this.classLoader = classLoader; this.clazz = clazz; } /** * Return the path for this resource (as resource path within the class path). */ public final String getPath() { return this.path; } /** * Return the ClassLoader that this resource will be obtained from. */ public final ClassLoader getClassLoader() { return (this.classLoader != null ? this.classLoader : this.clazz.getClassLoader()); } /** * This implementation checks for the resolution of a resource URL. * @see java.lang.ClassLoader#getResource(String) * @see java.lang.Class#getResource(String) */ @Override public boolean exists() { URL url; if (this.clazz != null) { url = this.clazz.getResource(this.path); } else { url = this.classLoader.getResource(this.path); } return (url != null); } /** * This implementation opens an InputStream for the given class path resource. * @see java.lang.ClassLoader#getResourceAsStream(String) * @see java.lang.Class#getResourceAsStream(String) */ public InputStream getInputStream() throws IOException { InputStream is; if (this.clazz != null) { is = this.clazz.getResourceAsStream(this.path); } else { is = this.classLoader.getResourceAsStream(this.path); } if (is == null) { throw new FileNotFoundException(getDescription() + " cannot be opened because it does not exist"); } return is; } /** * This implementation returns a URL for the underlying class path resource. * @see java.lang.ClassLoader#getResource(String) * @see java.lang.Class#getResource(String) */ @Override public URL getURL() throws IOException { URL url; if (this.clazz != null) { url = this.clazz.getResource(this.path); } else { url = this.classLoader.getResource(this.path); } if (url == null) { throw new FileNotFoundException(getDescription() + " cannot be resolved to URL because it does not exist"); } return url; } /** * This implementation creates a ClassPathResource, applying the given path * relative to the path of the underlying resource of this descriptor. * @see org.springframework.util.StringUtils#applyRelativePath(String, String) */ @Override public Resource createRelative(String relativePath) { String pathToUse = StringUtils.applyRelativePath(this.path, relativePath); return new ClassPathResource(pathToUse, this.classLoader, this.clazz); } /** * This implementation returns the name of the file that this class path * resource refers to. * @see org.springframework.util.StringUtils#getFilename(String) */ @Override public String getFilename() { return StringUtils.getFilename(this.path); } /** * This implementation returns a description that includes the class path location. */ public String getDescription() { StringBuilder builder = new StringBuilder("class path resource ["); String pathToUse = path; if (this.clazz != null && !pathToUse.startsWith("/")) { builder.append(ClassUtils.classPackageAsResourcePath(this.clazz)); builder.append('/'); } if (pathToUse.startsWith("/")) { pathToUse = pathToUse.substring(1); } builder.append(pathToUse); builder.append(']'); return builder.toString(); } /** * This implementation compares the underlying class path locations. */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (obj instanceof ClassPathResource) { ClassPathResource otherRes = (ClassPathResource) obj; return (this.path.equals(otherRes.path) && ObjectUtils.nullSafeEquals(this.classLoader, otherRes.classLoader) && ObjectUtils.nullSafeEquals( this.clazz, otherRes.clazz)); } return false; } /** * This implementation returns the hash code of the underlying * class path location. */ @Override public int hashCode() { return this.path.hashCode(); } }