hessian系列之二：上传文件

hessian较早版本通过 byte[] 进行文件传输；4.0之后支持 InputStream 作为参数或返回值进行传输。

注意：hessian会读取整个文件，如果文件过大，会导致JVM内存溢出。可以通过控制上传文件的大小，设置合理的JVM参数，以及采用随机读取方式来解决。


1. 接口：

一般放在独立的工程中，供服务端和客户端引用

public interface Uploader {
	void upload(String filename, InputStream data);
}

2. 服务端：

实现类：

public class FileUploader implements Uploader {

	private static final Logger logger = LoggerFactory.getLogger(FileUploader.class);

	@Override
	public void upload(String filename, InputStream data) {
		BufferedInputStream bis = null;
		BufferedOutputStream bos = null;
		try {
			bis = new BufferedInputStream(data);
			bos = new BufferedOutputStream(new FileOutputStream("D:\\upload\\" + filename));
			byte[] buffer = new byte[8192];
			int r = bis.read(buffer, 0, buffer.length);
			while (r > 0) {
				bos.write(buffer, 0, r);
				r = bis.read(buffer, 0, buffer.length);
			}
		} catch (IOException e) {
			logger.error("File upload exception: ", e);
		} finally {
			if (bos != null) {
				try {
					bos.close();
				} catch (IOException e) {
					logger.error("Closing output exception: ", e);
				}
			}
			if (bis != null) {
				try {
					bis.close();
				} catch (IOException e) {
					logger.error("Closing input exception: ", e);
				}
			}
		}
	}
}

web.xml

  <servlet>
    <servlet-name>upload</servlet-name>
    <servlet-class>com.caucho.hessian.server.HessianServlet</servlet-class>
    <init-param>
      <param-name>home-class</param-name>
      <param-value>com.john.hessian.impl.FileUploader</param-value>
    </init-param>
    <init-param>
      <param-name>home-api</param-name>
      <param-value>com.john.hessian.intf.Uploader</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>upload</servlet-name>
    <url-pattern>/upload</url-pattern>
  </servlet-mapping>

在浏览器地址栏输入：http://localhost/hessian/upload，查看是否可以调用。

3. 客户端：
测试类：

public class FileUploaderTest {

	static final String url = "http://localhost/hessian/upload";

	@Test
	public void testFileUploader() throws MalformedURLException, FileNotFoundException {
		HessianProxyFactory factory = new HessianProxyFactory();
		Uploader uploader = (Uploader) factory.create(Uploader.class, url);
		InputStream data = new BufferedInputStream(new FileInputStream("D:\\test.7z"));
		uploader.upload("test.7z", data);
	}
}

依次启动服务端和客户端，查看指定文件是否上传成功。