ByteArrayResource：通过byte 数组构建Resource
public class ByteArrayResource extends AbstractResource {
private final byte[] byteArray;
private final String description;
/**
* This implementation returns a ByteArrayInputStream for the
* underlying byte array.
* @see java.io.ByteArrayInputStream
*/
public InputStream getInputStream() throws IOException {
return new ByteArrayInputStream(this.byteArray);
}
}
FileSystemResource：文件资源，可读写
public class FileSystemResource extends AbstractResource implements WritableResource {
private final File file;
private final String path;
/**
* This implementation opens a FileInputStream for the underlying file.
* @see java.io.FileInputStream
*/
public InputStream getInputStream() throws IOException {
return new FileInputStream(this.file);
}
/**
* This implementation opens a FileOutputStream for the underlying file.
* WritableResouce接口方法
* @see java.io.FileOutputStream
*/
public OutputStream getOutputStream() throws IOException {
return new FileOutputStream(this.file);
}
/**
* Create a new FileSystemResource from a file path.
* Note: When building relative resources via {@link #createRelative},
* it makes a difference whether the specified resource base path here
* ends with a slash or not. In the case of "C:/dir1/", relative paths
* will be built underneath that root: e.g. relative path "dir2" ->
* "C:/dir1/dir2". In the case of "C:/dir1", relative paths will apply
* at the same directory level: relative path "dir2" -> "C:/dir2".
* @param path a file path
*/
public FileSystemResource(String path) {
Assert.notNull(path, "Path must not be null");
this.file = new File(path);
this.path = StringUtils.cleanPath(path);//路径处理：如前缀，..等
}
}
ClassPathResource:
通过给定的classLoader或者class加载资源文件
public class ClassPathResource extends AbstractFileResolvingResource {
private final String path;
private ClassLoader classLoader;
private Class clazz;
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;
//classLoader为空，则初始化当前线程的classLoader Thread.currentThread().getContextClassLoader();
this.classLoader = (classLoader != null ? classLoader : ClassUtils.getDefaultClassLoader());
}
}
资源文件方式：
/**
* 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;
}
