servlet 读取文件

读取pdf

protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("application/pdf");
		InputStream in = getServletContext().getResourceAsStream("/WEB-INF/java.pdf");
		OutputStream out = response.getOutputStream();
		writeBytes(in,out);
	}

	private void writeBytes(InputStream in, OutputStream out) throws IOException {
		byte[] buffer =new byte[1024];
		int length = -1;
		while ((length=in.read(buffer))!=-1) {
			out.write(buffer,0,length);
		}
		in.close();
		out.close();
		
	}

读取PNG

protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("image/png");
		File file = new File("F:\\OneDrive\\身份证\\888.jpg");//获取文件流
		System.out.println(file.getName());
		InputStream in = new FileInputStream(file);//文件流转输入流
		OutputStream out = response.getOutputStream();/获取输出流
		writeBytes(in,out);//输出文件
	}

	private void writeBytes(InputStream in, OutputStream out) throws IOException {
		byte[] buffer = new byte[1024];
		int length=-1;
		while((length=in.read(buffer))!=-1) {
			out.write(buffer, 0, length);
		}
		in.close();
		out.close();
	}