将上传的文件描述保存到数据库中，并显示到页面_如何实现用户上传数之后在页面上显示上传成功-优快云博客

本文链接：https://blog.youkuaiyun.com/xiaobiaobiao521/article/details/8931875

思想：

创建一个数据库：

mysql> use imgs;

Database changed

mysql> create table img(idvarchar(32),oldname varchar(100),

-> newname varchar(100),ip varchar(30),dt varchar(19));

1.写上传页面up.jsp

<body>

<form action="<c:url value='/Up2Servlet'/>"method="post"

enctype="multipart/form-data">

File:<input type="file" name="nm"><br /><input type="submit">

</form>

</body>

2.写上传Servlet Up2Servlet

public class Up2Servlet extends HttpServlet {

private Up2Dao dao= new Up2Dao();

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException,IOException {

request.setCharacterEncoding("UTF-8");

String path = getServletContext().getRealPath("/up");

DiskFileItemFactory disk = new DiskFileItemFactory();//声明临时文件

ServletFileUpload sfu = newServletFileUpload(disk);//声明解析request的核心类

//声明一个Map用于传递参数

Map<String,Object> img = new HashMap<String, Object>();

try {

List<FileItem>files = sfu.parseRequest(request);//解析request

FileItem file = files.get(0);

String fileName =file.getName();//获取文件名

fileName =fileName.substring(fileName.lastIndexOf("\\")+1);

img.put("oldname", fileName);

//获取扩展名

String exName =fileName.substring(fileName.lastIndexOf("."));

Stringuuid = UUID.randomUUID().toString().replace("-","");

StringnewName = uuid+exName;//新名字

//计算文件夹名

int hashCode = uuid.hashCode();

String dir1 = Integer.toHexString(hashCode&0xff);

String dir2 = Integer.toHexString((hashCode>>8)&0xff);

//组成目录

String relPath = path+"/"+dir1+"/"+dir2;

//判断目录是否存在

File f = new File(relPath);

if(!f.exists()){

f.mkdirs();

}

FileUtils.copyInputStreamToFile(file.getInputStream(),newFile(f,newName));

img.put("newname",dir1+"/"+dir2+"/"+newName);

img.put("ip", request.getRemoteAddr());

//去保存

dao.save(img);

//重定向到Queryservlet

response.sendRedirect(request.getContextPath()+"/QueryServlet");

}catch(Exception e) {

e.printStackTrace();

}

3.保存到数据库

public classUp2Dao {

public voidsave(Map<String,Object> img){

String sql = "insert into img values(?,?,?,?,?)";

QueryRunner run = newQueryRunner(DataSourceUtils.getDs());

String id = UUID.randomUUID().toString().replace("-", "");

String dt= new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());

run.update(sql,id, img.get("oldname"),img.get("newname"),img.get("ip"),dt);

}

4.查询数据库的Servlet

publicclassQueryServlet extends HttpServlet {

privatestaticfinallongserialVersionUID= 1L;

private QueryDao dao = new QueryDao();

publicvoiddoGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{

List<Map<String,Object>>list = dao.query();

//放到requset中转发

request.setAttribute("list", list);

request.getRequestDispatcher("/jsps/show1.jsp").forward(request,response);

}

5.查询数据库的dao

public class QueryDao {

public List<Map<String,Object>> query(){

String sql= "select * from img";

QueryRunner run = new QueryRunner(DataSourceUtils.getDs());

List<Map<String,Object>> list =run.query(sql, newMapListHandler());

return list;

}

6.显示页面show.jsp

div {

border: 1px solid red;

float: left;

width: 160px;

height: 180px;

text-align: center;

}

img {

width: 160px;

height: 160px;

}

</style>

</head>

<body>

<c:forEach items="${list}" var="mm"varStatus="idx">

<div>

<a href="<c:url value='/up/${mm.newname}'/>"><img

src="<c:url value='/up/${mm.newname}'/>">

</a>

<c:choose>

<c:when test="${fn:length(mm.oldname)>=6}">

${fn:substring(mm.oldname,0,7) }...

</c:when>

<c:otherwise>

${mm.oldname }

</c:otherwise>

</c:choose>

${mm.ip}

</div>

</c:forEach>

</body>