Spring中的资源都被封装成 Resource 对象

 以上是我测试代码的项目编译后的目录结构，target 所在的目录是 

D:\\IdeaProjects\\study-spring\\

public void printStream(InputStream inputStream) throws IOException {


    Reader reader = new InputStreamReader(inputStream);

    BufferedReader bufferedReader = new BufferedReader(reader);

    String line = null;

    while ( (line = bufferedReader.readLine()) != null) {
        System.out.println(line);
    }
}

1.ClassPathResource 

ClassPathResource 是以classes目录为根目录进行查找，开头可以带 / 也可以不带

@Test
public void classPathResource() throws IOException {
    Resource resource = new 
       ClassPathResource("com/fll/start/resource_loader/InputResourceTest.class");
    InputStream inputStream = resource.getInputStream();
    printStream(inputStream);
}

 读取到了InputResourceTest.class的内容

@Test
public void classPathResource1() throws IOException {
    Resource resource = new ClassPathResource("beans.xml");
    InputStream inputStream = resource.getInputStream();
    printStream(inputStream);
}

 读取到了beans.xml的内容

2. FileSystemResource

FileSystemResource 是根据资源在磁盘上的绝对路劲进行加载的

@Test
public void fileSystemResource() throws IOException {

    Resource resource = new FileSystemResource("D:\\IdeaProjects\\study-spring\\target\\classes\\beans.xml");
    InputStream inputStream = resource.getInputStream();
    printStream(inputStream);
}

 成功加载到了beans.xml

 3.PathResource

 PathResource 和 FileSystemResource 有点类似可以按照磁盘绝对路劲加载资源，不同的是，PathResource是可以支持按照相对路径加载资源
按照绝对路径进行加载

@Test
public void pathResource() throws IOException {

    PathResource pathResource = new PathResource("D:\\IdeaProjects\\study-spring\\target\\classes\\com/fll/start/resource_loader/InputResourceTest.class");
    InputStream inputStream = pathResource.getInputStream();
    printStream(inputStream);
}

按照相对路劲进行加载

@Test
public void relativePathResource() throws IOException {

    PathResource pathResource = new PathResource("D:/IdeaProjects/study-spring/target/classes/com/fll/start/resource_loader/InputResourceTest.class");
    Resource relative = pathResource.createRelative("../DefaultResourceLoaderTest.class");
    InputStream inputStream = relative.getInputStream();
    printStream(inputStream);
}

@Test
public void relativePathResource1() throws IOException {

    PathResource pathResource = new PathResource("D:/IdeaProjects/study-spring/target/classes/com/fll/start/resource_loader/InputResourceTest.class");
    Resource relative = pathResource.createRelative("../../../../../beans.xml");
    InputStream inputStream = relative.getInputStream();
    printStream(inputStream);
}

都可以成功的加载到对应的资源

4.UrlResource

 UrlResource 可以用来加载 网络上的相关资源

@Test
public void urlResource() throws IOException {

    Resource resource = new UrlResource("https://www.baidu.com");

    InputStream inputStream = resource.getInputStream();

    printStream(inputStream);

}