Java web项目下载图片/文件 ^原

Java web项目下载图片/文件

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import javax.servlet.http.HttpServletResponse;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import com.xql.test.common.IOUtil;

@Controller
public class TestController {


@RequestMapping(value = "test/fileDownload")
        //测试
	@RequestMapping(value = "test/fileDownload")
	public void fileDownload(HttpServletResponse response) {

		// 图片流
		InputStream imgInputStream = null;
		// 输出流
		OutputStream os = null;
		try {
			// 1.从网络中读取到一张图片
			// 创建URL对象[这里引用的百度logo的图片地址]
			String imageUrl = "https://www.baidu.com/img/bd_logo1.png";
			URL url = new URL(imageUrl);
			HttpURLConnection conn = (HttpURLConnection) url.openConnection();
			conn.setRequestMethod("GET");
			conn.setReadTimeout(5 * 1000);
			// 获取图片输入流
			imgInputStream = conn.getInputStream();
			// 2.将inputstream流转换为byte[]/数据
			byte[] imgBytes = IOUtil.inputStream2byte(imgInputStream);
			// 3.获得response中的输出流
			os = response.getOutputStream();
			// 4.设置输出的一些参数
			// 4.1设置输出文件名
			String fileName = imageUrl.substring(imageUrl.lastIndexOf("/"),
					imageUrl.length());
			response.setHeader("Content-Disposition", "attachment; filename=\""
					+ fileName + "\"");
			// 4.2设置下载页面文件显示大小
			response.addHeader("Content-Length", "" + imgBytes.length);
			// 4.3设置content类型
			response.setContentType("application/octet-stream;charset=UTF-8");
			// 5.将图片输出
			os.write(imgBytes);

		} catch (Exception e) {
			System.err.println(e.getMessage());
		} finally {
			// 6.无论成功与否关闭相应的流
			try {
				if (imgInputStream != null) {
					imgInputStream.close();
				}
				if (os != null) {
					os.close();
				}
			} catch (IOException e) {
				System.err.println(e.getMessage());
			}

		}
	}
}

注意事项
①IOUtil.inputStream2byte(InputStream is) 工具类,将inputstream 转换为byte数组

②获取的response是来自于HttpServletResponse