Spring的资源文件访问功能使用起来十分简单,调用ApplicationContext.getResource的方法即可:
- Resource template = ctx.getResource("some/resource/path/myTemplate.txt");
- Resource template = ctx.getResource("classpath:some/resource/path/myTemplate.txt");
- Resource template = ctx.getResource("file:/some/resource/path/myTemplate.txt");
- Resource template = ctx.getResource("http://myhost.com/resource/path/myTemplate.txt");
Resource template = ctx.getResource("some/resource/path/myTemplate.txt"); Resource template = ctx.getResource("classpath:some/resource/path/myTemplate.txt"); Resource template = ctx.getResource("file:/some/resource/path/myTemplate.txt"); Resource template = ctx.getResource("http://myhost.com/resource/path/myTemplate.txt");
二)resource的深入了解
其实知道了以上的gerResource方法,就已经能够满足我们日常的资源文件访问的需要了。但本着精益求精的精神,我们不妨看下spring的源码,看看spring到底是如何实现这个功能模块的。首先是接口Resource:
- public interface Resource extends InputStreamSource {
- boolean exists();
- boolean isOpen();
- URL getURL() throws IOException;
- File getFile() throws IOException;
- Resource createRelative(String relativePath) throws IOException;
- String getFilename();
- String getDescription();
- }
- public interface InputStreamSource {
- InputStream getInputStream() throws IOException;
- }
public interface Resource extends InputStreamSource { boolean exists(); boolean isOpen(); URL getURL() throws IOException; File getFile() throws IOException; Resource createRelative(String relativePath) throws IOException; String getFilename(); String getDescription(); } public interface InputStreamSource { InputStream getInputStream() throws IOException; }
基于这个底层接口,spring运用多态继承了一系列的子类以满足不同形式的资源文件访问:
UrlResource: file: http: ftp: 的资源访问形式都是它处理啦
ClassPathResource: 看名字也猜的出来classpath:的资源访问形式就是它处理的
FileSystemResource: 从文件系统路径获取资源文件,C:\XXXXX
ServletContextResource: web应用中从context下获取资源文件,相对路径绝对路径均可
InputStreamResource: 缺省的Resource类,如果根据输入的url形式找不到对应的Resource,那么就调用它了...当然我们也可以显示的调用它:
- @Test
- public void testInputStreamResource() {
- ByteArrayInputStream bis = new ByteArrayInputStream("Hello World!".getBytes());
- Resource resource = new InputStreamResource(bis);
- if(resource.exists()) { ...... }
- }
@Test public void testInputStreamResource() { ByteArrayInputStream bis = new ByteArrayInputStream("Hello World!".getBytes()); Resource resource = new InputStreamResource(bis); if(resource.exists()) { ...... } }
ByteArrayResource: 看代码便知...
- @Test
- public void testByteArrayResource() {
- Resource resource = new ByteArrayResource("Hello World!".getBytes());
- if(resource.exists()) { ...... }
- }
@Test public void testByteArrayResource() { Resource resource = new ByteArrayResource("Hello World!".getBytes()); if(resource.exists()) { ...... } }
三)ResourceLoaderAware
和其它Aware一样,继承此接口后,当此bean实例化时会自动调用setResourceLoader(ResourceLoader resourceLoader)方法。
- public interface ResourceLoaderAware {
- void setResourceLoader(ResourceLoader resourceLoader);
- }
public interface ResourceLoaderAware { void setResourceLoader(ResourceLoader resourceLoader); }
四) Resource的注入
那么,如果是一个resouce类,Spring在配置文件中改如何处理以使它自动注入呢?样例如下:
- <bean id="myBean" class="...">
- <property name="template" value="some/resource/path/myTemplate.txt"/>
- </bean>
- <property name="template" value="classpath:some/resource/path/myTemplate.txt">
- <property name="template" value="file:/some/resource/path/myTemplate.txt"/>
<bean id="myBean" class="..."> <property name="template" value="some/resource/path/myTemplate.txt"/> </bean> <property name="template" value="classpath:some/resource/path/myTemplate.txt"> <property name="template" value="file:/some/resource/path/myTemplate.txt"/>
十分方便吧~~
五)资源文件的通配样式
当你需要一次获取多个资源文件时,你可以考虑采用以下一些通配的手段:
- /WEB-INF/*-context.xml
- com/mycompany/**/applicationContext.xml
- file:C:/some/path/*-context.xml
- classpath:com/mycompany/**/applicationContext.xml
- classpath*:conf/appContext.xml //获取classpath内所有的conf/appContext.xml,不加*的话只会加载搜索时遇到的第一个匹配文件