【Java】Java从网络读取图片并保存至本地

灰太狼 2022-06-15 00:10 489阅读 0赞

一、js代码：

![20170518134742069][]

代码如下：

/** * 点击下载当前图片 * */ function downloadThisImage(obj){ var tid = $(obj).attr("file_tid"); var fileSrc = $(obj).parent().prev().attr("src"); window.location.href='../../file/toDownloadHmImage.do?tid='+tid+'&fileSrc='+fileSrc; }

二、图片下载的公共方法

package com.zxct.edu.utils; import java.io.ByteArrayOutputStream; import java.io.InputStream; import java.io.OutputStream; import java.net.URL; import java.net.URLConnection; import javax.servlet.http.HttpServletResponse; public class ImagesUtil { public static void download2(HttpServletResponse response,String urlString, String filename) throws Exception { //new一个URL对象 URL url = new URL(urlString); //打开链接 URLConnection conn = url.openConnection(); //超时响应时间为5秒 conn.setConnectTimeout(5 * 1000); //通过输入流获取图片数据 InputStream inStream = conn.getInputStream(); //得到图片的二进制数据，以二进制封装得到数据，具有通用性 byte[] data = readInputStream(inStream); //new一个文件对象用来保存图片，默认保存当前工程根目录 //File imageFile = new File(filename); //创建输出流 OutputStream outStream = response.getOutputStream(); //写入数据 outStream.write(data); //关闭输出流 outStream.close(); } public static void download(HttpServletResponse response,String urlString, String filename) throws Exception { // 构造URL URL url = new URL(urlString); // 打开连接 URLConnection con = url.openConnection(); //超时响应时间为10秒 con.setConnectTimeout(10 * 1000); // 输入流 InputStream is = con.getInputStream(); // 1K的数据缓冲 byte[] bs = new byte[1024]; // 读取到的数据长度 int len; // 输出的文件流 OutputStream os =response.getOutputStream(); // 开始读取 while ((len = is.read(bs)) != -1) { os.write(bs, 0, len); } // 完毕，关闭所有链接 os.close(); is.close(); } public static byte[] readInputStream(InputStream inStream) throws Exception{ ByteArrayOutputStream outStream = new ByteArrayOutputStream(); //创建一个Buffer字符串 byte[] buffer = new byte[1024]; //每次读取的字符串长度，如果为-1，代表全部读取完毕 int len = 0; //使用一个输入流从buffer里把数据读取出来 while( (len=inStream.read(buffer)) != -1 ){ //用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度 outStream.write(buffer, 0, len); } //关闭输入流 inStream.close(); //把outStream里的数据写入内存 return outStream.toByteArray(); } }

注：download和download2方法均能实现下载。

三、Controller接口方法：

/** * 下载图片文件 * @param request * @param response * @param model * @return * @throws ServletException * @throws IOException * @author zhangsq */ @RequestMapping("/toDownloadHmImage.do") public void toDownloadHmImage(HttpServletRequest request, HttpServletResponse response, ModelMap model,String fileSrc,String tid) throws ServletException, IOException { String filePath = fileSrc.substring(0,fileSrc.indexOf("?")); String realname = filePath.substring(filePath.lastIndexOf("/")+1); // 设置响应头，控制浏览器下载该文件 response.reset(); response.setStatus(HttpServletResponse.SC_OK); response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(realname, "UTF-8")); try { ImagesUtil.download(response,filePath, realname); } catch (Exception e) { e.printStackTrace(); ServletOutputStream sos = null; try { response.setContentType("text/html;charset=utf-8"); sos = response.getOutputStream(); sos.write("<script>alert('下载失败，请与管理员联系~~');</script>".getBytes()); sos.flush(); } catch (IOException e1) { e1.printStackTrace(); }finally{ if(null != sos){ try { sos.close(); } catch (IOException e1) { e1.printStackTrace(); } } } } }

[20170518134742069]: /images/20220615/c41a50c65e114956b87dc7034f513363.png