基于SpringBoot实现图片上传与显示

<dependencies>
 <!--FreeMarker模板视图依赖-->
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-freemarker</artifactId>
  </dependency>

  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
  </dependency>

  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-test</artifactId>
   <scope>test</scope>
  </dependency>
</dependencies>

server.port=8102

### FreeMarker 配置
spring.freemarker.allow-request-override=false
#Enable template caching.启用模板缓存。
spring.freemarker.cache=false
spring.freemarker.check-template-location=true
spring.freemarker.charset=UTF-8
spring.freemarker.content-type=text/html
spring.freemarker.expose-request-attributes=false
spring.freemarker.expose-session-attributes=false
spring.freemarker.expose-spring-macro-helpers=false
#设置面板后缀
spring.freemarker.suffix=.ftl

# 设置单个文件最大内存
multipart.maxFileSize=50Mb
# 设置所有文件最大内存
multipart.maxRequestSize=50Mb
# 自定义文件上传路径
web.upload-path=E:/Develop/Files/Photos/

package com.wu.demo.fileupload.demo.util;

public class FileNameUtils {

 /**
  * 获取文件后缀
  * @param fileName
  * @return
  */
 public static String getSuffix(String fileName){
  return fileName.substring(fileName.lastIndexOf("."));
 }

 /**
  * 生成新的文件名
  * @param fileOriginName 源文件名
  * @return
  */
 public static String getFileName(String fileOriginName){
  return UUIDUtils.getUUID() + FileNameUtils.getSuffix(fileOriginName);
 }

}

import java.util.UUID;

/**
 * 生成文件名
 */
public class UUIDUtils {

 public static String getUUID(){
  return UUID.randomUUID().toString().replace("-", "");
 }

}

package com.wu.demo.fileupload.demo.util;

import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;

/**
 * 文件上传工具包
 */
public class FileUtils {

 /**
  *
  * @param file 文件
  * @param path 文件存放路径
  * @param fileName 源文件名
  * @return
  */
 public static boolean upload(MultipartFile file, String path, String fileName){

  // 生成新的文件名
  //String realPath = path + "/" + FileNameUtils.getFileName(fileName);

  //使用原文件名
  String realPath = path + "/" + fileName;

  File dest = new File(realPath);

  //判断文件父目录是否存在
  if(!dest.getParentFile().exists()){
   dest.getParentFile().mkdir();
  }

  try {
   //保存文件
   file.transferTo(dest);
   return true;
  } catch (IllegalStateException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
   return false;
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
   return false;
  }

 }
}

package com.wu.demo.fileupload.demo.controller;

import com.wu.demo.fileupload.demo.util.FileUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.io.ResourceLoader;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.util.Map;

@Controller
public class TestController {

 private final ResourceLoader resourceLoader;

 @Autowired
 public TestController(ResourceLoader resourceLoader) {
  this.resourceLoader = resourceLoader;
 }

 @Value("${web.upload-path}")
 private String path;

 /**
  * 跳转到文件上传页面
  * @return
  */
 @RequestMapping("test")
 public String toUpload(){
  return "test";
 }

 /**
  *
  * @param file 要上传的文件
  * @return
  */
 @RequestMapping("fileUpload")
 public String upload(@RequestParam("fileName") MultipartFile file, Map<String, Object> map){

  // 要上传的目标文件存放路径
  String localPath = "E:/Develop/Files/Photos";
  // 上传成功或者失败的提示
  String msg = "";

  if (FileUtils.upload(file, localPath, file.getOriginalFilename())){
   // 上传成功，给出页面提示
   msg = "上传成功！";
  }else {
   msg = "上传失败！";

  }

  // 显示图片
  map.put("msg", msg);
  map.put("fileName", file.getOriginalFilename());

  return "forward:/test";
 }

 /**
  * 显示单张图片
  * @return
  */
 @RequestMapping("show")
 public ResponseEntity showPhotos(String fileName){

  try {
   // 由于是读取本机的文件，file是一定要加上的， path是在application配置文件中的路径
   return ResponseEntity.ok(resourceLoader.getResource("file:" + path + fileName));
  } catch (Exception e) {
   return ResponseEntity.notFound().build();
  }
 }

}

<!DOCTYPE html>
<head>
 <meta charset="UTF-8" />
 <title>图片上传Demo</title>
</head>
<body>
<h1 >图片上传Demo</h1>
<form action="fileUpload" method="post" enctype="multipart/form-data">
 <p>选择文件: <input type="file" name="fileName"/></p>
 <p><input type="submit" value="提交"/></p>
</form>
<#--判断是否上传文件-->
<#if msg??>
 <span>${msg}</span><br>
<#else >
 <span>${msg!("文件未上传")}</span><br>
</#if>
<#--显示图片，一定要在img中的src发请求给controller，否则直接跳转是乱码-->
<#if fileName??>
<img src="/show?fileName=${fileName}" style="width: 200px"/>
<#else>
<img src="/show" style="width: 100px"/>
</#if>
</body>
</html>