spring boot实现图片上传和下载功能

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呐喊教程。

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