JavaEE项目上传图片例子

布满荆棘的人生 2022-03-30 10:30 189阅读 0赞

1.上传图片前端：

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
    <form action="Servlet01" method="post" enctype="multipart/form-data">
    用户名：<input type="text" name="username"><br>
    密码：<input type="password" name="password"><br>
    头像：<input type="file" name="head"><br>
    <button>提交</button>
    </form>
    </body>
    </html>

\---重要的是要设置enctype才能传文件，但是由于设置了enctype后，request.getParameter(“”)函数将无法获取到正确的键值对数据，全部为null;

2.Servlet01代码：

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		/*String name = request.getParameter("username");
    		String pass = request.getParameter("password");
    		String head = request.getParameter("head");
    		System.out.println(name+"  "+pass+"  "+head);*///null null null
    		//getParameter()获取的是请求体部分为键值对或浏览器路径的键值对
    		//获取输入流对象
    		//ServletInputStream inputStream = request.getInputStream();
    		//读一个数据
    		/*int i = inputStream.read();
    		while(i!=-1){
    			char c=(char)i;
    			System.out.print(c);
    			i=inputStream.read();
    		}
    		*/
    		//获取请求体全部内容，并解析，分割线内容封装在FileItem
    		DiskFileItemFactory fac=new DiskFileItemFactory();
    		ServletFileUpload upload= new ServletFileUpload(fac);
    		upload.setHeaderEncoding("utf-8");//解决上传文件名的乱码
    		Map<String,String> map=new HashMap<String,String>();
    		String name="";
    		User user = new User();
    		try {
    			List<FileItem> list=upload.parseRequest(request);
    			for (FileItem fileItem : list) {
    				if(fileItem.isFormField()){
    					//普通项,username,aaa
    					//解决普通属性的乱码
    					map.put(fileItem.getFieldName(),fileItem.getString("utf-8"));//
    				}else{
    					//上传项
    					InputStream inputStream = fileItem.getInputStream();
    					String path = getServletContext().getRealPath("/images/img/");
    					//路径和文件名
    					name=fileItem.getName();//获取上传的文件名
    					File file= new File(path,name);
    					//服务端建立一个空文件
    					if(!file.exists()){
    						file.createNewFile();
    					}
    					//文件存不存在都会执行，就会导致文件重名（重复上传）覆盖问题
    					OutputStream out = new FileOutputStream(file);
    					//写入输出流
    					IOUtils.copy(inputStream, out);
    					IOUtils.closeQuietly(inputStream);
    					IOUtils.closeQuietly(out);
    					
    					map.put(fileItem.getFieldName(), "/images/img/"+name);
    				}
    			}
    			//保存用户数据
    			BeanUtils.populate(user, map);//map的数据填充到user里保存
    		} catch (FileUploadException | IllegalAccessException | InvocationTargetException e) {
    			e.printStackTrace();
    		}
    	}

上面使用到了开源工具用来解析http请求体的数据

![20190105200025655.png][]

/images/img/是位于tomcat的当前项目目录下的目录。

[20190105200025655.png]: /images/20220330/47a8bba8e712435eb71b77d9e6ee20ec.png