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
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\
spring boot多文件上传：
核心代码：
/**
* 多文件上传
* @param files
* @return
* @throws RuntimeException
*/
@RequestMapping(value = "/uploadFiles", method = RequestMethod.POST)
public JSONObject uploadFiles(@RequestParam(value = "file") MultipartFile[] files){
StringBuffer result = new StringBuffer();
try {
for (int i = 0; i < files.length; i++) {
if (files[i] != null) {
//调用上传方法
String fileName = executeUpload(files[i]);
result.append(fileName+";");
}
}
} catch (Exception e) {
e.printStackTrace();
JsonUtil.getFailJsonObject("文件上传失败");
}
return JsonUtil.getSuccessJsonObject(result.toString());
}
/**
* 提取上传方法为公共方法
* @param file
* @return
* @throws Exception
*/
private String executeUpload(MultipartFile file)throws Exception{
//文件后缀名
String suffix = file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf("."));
//上传文件名
String fileName = UUID.randomUUID()+suffix;
//服务端保存的文件对象
File serverFile = new File(uploadDir + fileName);
// 检测是否存在目录
if (!serverFile.getParentFile().exists()) {
serverFile.getParentFile().mkdirs();
}
//将上传的文件写入到服务器端文件内
file.transferTo(serverFile);
return fileName;
}