Spring Resources

Resources接口

针对于资源文件的统一接口
UrlResource: URL对应的资源，根据一个URL地址即可构建
ClassPathResource: 获取类路径下的资源文件
FileSystemResource: 获取文件系统里面的资源
ServletContextResource: ServletContext封装的资源，用于访问ServletContext环境下的资源
InputStreamResource: 针对于输入流封装的资源
ByteArrayResource: 针对于字节数组封装的资源

ResourceLoader

All application contexts implement the ResourceLoader interface，and therefore all application contexts
may be used to obtain Resource instances.
语义: 所有的applicationContext都实现了ResourceLoader接口，可以使用getResource方法获取资源实例
主要方法: public Resource getResource(String arg0);
支持的路径前缀: 如果是默认则根据applicationContext实例的创建方式

Resource

boolean exists(): 判断该资源是否存在
URL getURL(): 获取资源的物理路径，资源不存在会抛出异常
String getFilename(): 获取资源名称，即使资源不存在也能返回要查找的名称
long contentLength(): 获取资源内容长度，资源不存在抛出异常
示例：

import java.io.IOException;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.core.io.Resource;


public class MoocResource implements ApplicationContextAware  {
    
    private ApplicationContext applicationContext;
    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext)
            throws BeansException {
        this.applicationContext = applicationContext;
    }
    
    public void resource() throws IOException {
        //通过url方式返回长度为-1
        //Resource resource = applicationContext.getResource("https://spring.io/docs");
        //Resource resource = applicationContext.getResource("file:/D:/workspace/Spring/classes/config.txt");
        //Resource resource = applicationContext.getResource("classpath:config.txt");
        //因为applicationContext是通过classpath加载，所以不写前缀也一样
        Resource resource = applicationContext.getResource("config.txt");
        System.out.println(resource.getFilename());//config.txt
        if(resource.exists()){
            System.out.println(resource.getURL());//file:/D:/workspace/Spring/classes/config.txt
            System.out.println(resource.contentLength());//9
        }
        
    }
}
@RunWith(BlockJUnit4ClassRunner.class)
public class TestResource extends UnitTestBase {
    
    public TestResource() {
        super("classpath:spring-resource.xml");
    }
    
    @Test
    public void testResource() {
        MoocResource resource = super.getBean("moocResource");
        try {
            resource.resource();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
<bean  id="moocResource" class="com.imooc.resource.MoocResource" ></bean>