这篇博客简单介绍下spring boot下图片上传和下载，已经遇到的问题。首先需要创建一个spring boot项目。
1、核心的controller代码
package com.qwrt.station.websocket.controller; import com.alibaba.fastjson.JSONObject; import com.qwrt.station.common.util.JsonUtil; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Value; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.multipart.MultipartFile; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.*; /** * Created by jack on 2017/10/30. */ @RestController @RequestMapping("v1/uploadDownload") public class UploadDownloadController { private static final Logger logger = LoggerFactory.getLogger(UploadDownloadController.class); @Value("${uploadDir}") private String uploadDir; @RequestMapping(value = "/uploadImage", method = RequestMethod.POST) public JSONObject uploadImage(@RequestParam(value = "file") MultipartFile file) throws RuntimeException { if (file.isEmpty()) { return JsonUtil.getFailJsonObject("文件不能为空"); } // 获取文件名 String fileName = file.getOriginalFilename(); logger.info("上传的文件名为：" + fileName); // 获取文件的后缀名 String suffixName = fileName.substring(fileName.lastIndexOf(".")); logger.info("上传的后缀名为：" + suffixName); // 文件上传后的路径 String filePath = uploadDir; // 解决中文问题，liunx下中文路径，图片显示问题 // fileName = UUID.randomUUID() + suffixName; File dest = new File(filePath + fileName); // 检测是否存在目录 if (!dest.getParentFile().exists()) { dest.getParentFile().mkdirs(); } try { file.transferTo(dest); logger.info("上传成功后的文件路径未：" + filePath + fileName); return JsonUtil.getSuccessJsonObject(fileName); } catch (IllegalStateException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return JsonUtil.getFailJsonObject("文件上传失败"); } //文件下载相关代码 @RequestMapping(value = "/downloadImage",method = RequestMethod.GET) public String downloadImage(String imageName,HttpServletRequest request, HttpServletResponse response) { //String fileName = "123.JPG"; logger.debug("the imageName is : "+imageName); String fileUrl = uploadDir+imageName; if (fileUrl != null) { //当前是从该工程的WEB-INF//File//下获取文件(该目录可以在下面一行代码配置)然后下载到C://users//downloads即本机的默认下载的目录 /* String realPath = request.getServletContext().getRealPath( "//WEB-INF//");*/ /*File file = new File(realPath, fileName);*/ File file = new File(fileUrl); if (file.exists()) { response.setContentType("application/force-download");// 设置强制下载不打开 response.addHeader("Content-Disposition", "attachment;fileName=" + imageName);// 设置文件名 byte[] buffer = new byte[1024]; FileInputStream fis = null; BufferedInputStream bis = null; try { fis = new FileInputStream(file); bis = new BufferedInputStream(fis); OutputStream os = response.getOutputStream(); int i = bis.read(buffer); while (i != -1) { os.write(buffer, 0, i); i = bis.read(buffer); } System.out.println("success"); } catch (Exception e) { e.printStackTrace(); } finally { if (bis != null) { try { bis.close(); } catch (IOException e) { e.printStackTrace(); } } if (fis != null) { try { fis.close(); } catch (IOException e) { e.printStackTrace(); } } } } } return null; } } 上面的代码有两个方法，上面的方法是图片上传的方法，下面的方法是图片下载的方法。下载图片需要传入图片的文件名，在ios，android手机，谷歌浏览器测试，上传下载没有问题。
2、测试的html的核心代码如下，进行图片的上传和下载：
<!DOCTYPE html> <html> <head> <meta charset="UTF-8" /> <title>websocket chat</title> </head> <body> <div> <label>输入信息：</label><input id="id" width="100px" /><br /> <button id="btn">发送消息</button> <button id="connection">websocket连接</button> <button id="disconnection">断开websocket连接</button> <br /><br /> <form enctype="multipart/form-data" id="uploadForm"> <input type="file" name="uploadFile" id="upload_file" style="margin-bottom:10px;"> <input type="button" id="uploadPicButton" value="上传" onclick="uploadImage()"> </form> <!--<input type="file" onchange="uploadImgTest();" id="uploadImg" name="uploadImg" /> <button id="uploadImage" onclick="uploadImage();">上传</button>--> </div> <div id="test"> </div> <hr color="blanchedalmond"/> <div id="voiceDiv"> </div> <hr color="chartreuse" /> <div id="imgDiv" style="width: 30%;height: 30%;"> <img src="http://192.168.9.123:8860/v1/uploadDownload/downloadImage?imageName=123.JPG" style="width: 160px;height: 160px;"/> </div> </body> <script src="js/jquery-3.2.1.min.js"></script> <!--<script th:src="@{stomp.min.js}"></script>--> <script src="js/sockjs.min.js"></script> <script> var websocketUrl = "ws://192.168.9.123:8860/webSocketServer"; var websocket; if('WebSocket' in window) { //websocket = new WebSocket("ws://" + document.location.host + "/webSocketServer"); //websocket = new WebSocket("ws://192.168.9.123:9092/webSocketServer"); //websocket = new WebSocket("ws://localhost:8860/webSocketServer"); websocket = new WebSocket(websocketUrl); } else if('MozWebSocket' in window) { websocket = new MozWebSocket("ws://" + document.location.host + "/webSocketServer"); } else { websocket = new SockJS("http://" + document.location.host + "/sockjs/webSocketServer"); } websocket.onopen = function(evnt) { console.log("onopen----", evnt.data); }; websocket.onmessage = function(evnt) { //$("#test").html("(<font color='red'>" + evnt.data + "</font>)"); console.log("onmessage----", evnt.data); //$("#test").html(evnt.data); $("#test").append('<div>' + event.data + '</div>'); }; websocket.onerror = function(evnt) { console.log("onerror----", evnt.data); } websocket.onclose = function(evnt) { console.log("onclose----", evnt.data); } $('#btn').on('click', function() { if(websocket.readyState == websocket.OPEN) { var msg = $('#id').val(); //调用后台handleTextMessage方法 websocket.send(msg); } else { alert("连接失败!"); } }); $('#disconnection').on('click', function() { if(websocket.readyState == websocket.OPEN) { websocket.close(); //websocket.onclose(); console.log("关闭websocket连接成功"); } }); $('#connection').on('click', function() { if(websocket.readyState == websocket.CLOSED) { websocket.open(); //websocket.onclose(); console.log("打开websocket连接成功"); } }); //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。 window.onbeforeunload = function() { websocket.close(); } function uploadImgTest() { } function uploadImage(){ //var uploadUrl = "http://localhost:8860/v1/uploadDownload/uploadImage"; var uploadUrl = "http://192.168.9.123:8860/v1/uploadDownload/uploadImage"; var downUrl = "http://192.168.9.123:8860/v1/uploadDownload/downloadImage" var pic = $('#upload_file')[0].files[0]; var fd = new FormData(); //fd.append('uploadFile', pic); fd.append('file', pic); $.ajax({ url:uploadUrl, type:"post", // Form数据 data: fd, cache: false, contentType: false, processData: false, success:function(data){ console.log("the data is : {}",data); if(data.code == 0){ console.log("上传成功后的文件路径为："+data.data); var img = $("<img />") img.attr("src",downUrl+"?imageName="+data.data); img.width("160px"); img.height("160px"); $("#imgDiv").append(img); } } }); } </script> </html> 上面的代码有些和图片的上传和下载没有关系，根据需要自己去掉，看图片上传和下载的核心代码，需要引入jquery。
3、spring boot的属性配置：
1.解决图片上传太大的问题：
spring: http: multipart: max-file-size: 100Mb #文件上传大小 max-request-size: 200Mb #最打请求大小
这是新版spring boot解决图片或者文件上传太大的问题，老板的不是这样解决的。可以自己查资料
2.配置文件上传保存的位置：
#上传位置uploadDir: F:/mystudy/pic/
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。
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