jsp+servlet简单实现上传文件功能（保存目录改进）

1、jsp前端

<%–
Created by IntelliJ IDEA.
User: Lenovo
Date: 2020/6/19
Time: 22:53
Learn from https://www.bilibili.com/video/BV18z411i7gh?t=23&p=192
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–%>
<%@ page contentType=\”text/html;charset=UTF-8\” language=\”java\” %>
<html>
<head>
<title>文件上传</title>
</head>
<body>
<!–文件上传对表单的要求–>
<!–
1、表单中的请求提交方式必须是POST
2、表单中应指定所提交的请求位multipart请求，通过在<form/>标签中添加enctype属性
其值为multipart/form-data
3、表单
–>
<form method=\”POST\” action=\”http://localhost:8888/hello/UploadImageServlet\” enctype=\”multipart/form-data\”>
编号<input type=\”text\” name=\”BNO\”></br>
名字<input type=\”text\” name=\”BNAME\”></br>
照片<input type=\”file\” name=\”picutreUrl\”></br>
<input type=\”submit\” value=\”注册\”>
</form>
</body>
</html>

2、servlet后台

package Servlet.bookServlet;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.List;

@WebServlet(name = \”UploadImageServlet\”)
public class UploadImageServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1、判断请求是不是multipart请求
if(!ServletFileUpload.isMultipartContent(request)){
throw new RuntimeException(\”当前请求不支持文件上传\”);
}
System.out.println(\”开始上传文件\”);
//2、创建FileItem工厂==>文件写入硬盘的作用
try {
DiskFileItemFactory factory = new DiskFileItemFactory();
//3、创建temp临时文件夹
String tempPath =\”D:\\\\tomcat\\\\apache-tomcat-9.0.35-windows-x64\\\\apache-tomcat-9.0.35\\\\webapps\\\\librarySystem\\\\web\\\\net\\\\temp\”;
File tempFile = new File(tempPath);
factory.setRepository(tempFile);
//4、设置使用临时文件的边界值,大于该值，上传文件先保存在临时文件中，小于该值，则直接写入内存
//单位是字节
factory.setSizeThreshold(1024*1024*1);

//5、创建文件上传核心组件
// 调用ServletFileUpload.parseRequest方法解析request对象，得到一个保存了所有上传内容的List对象。
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setHeaderEncoding(\”utf-8\”);//可以解决文件名中文乱码
upload.setFileSizeMax(1024*1024*2);

String bNo=\”defaultBNo\”,bName=\”defaultBName\”;
//6、解析请求
List<FileItem> items =upload.parseRequest(request);
//7、遍历请求
for(FileItem item:items){
//普通表单项，上传名字，编号等普通信息的上i传
if(item.isFormField()){
String fileName = item.getFieldName();// name属性值
String fileValue = item.getString(\”utf-8\”);// name对应的value值
System.out.println(fileName + \” — \” + fileValue);
if(fileName.equalsIgnoreCase(\”BNO\”)){
bNo = fileValue;
}
if(fileName.equalsIgnoreCase(\”BNAME\”)){
bName = fileValue;
}
}
else{//上传图片等
String fileName = item.getName();
System.out.println(\”上传文件名字:\”+fileName);
String suffix = fileName.substring(fileName.lastIndexOf(\’.\’));//获取文件类型
String newFileName = bNo+\”_\”+bName+suffix;
System.out.println(newFileName);
//获取输入流，其中有上传文件的内容
InputStream is = item.getInputStream();
//String path = this.getServletContext().getRealPath(\”/net/bookImage\”);//获得当前项目保存服务器地址，也就是web文件夹下
String path =\”D:\\\\tomcat\\\\apache-tomcat-9.0.35-windows-x64\\\\apache-tomcat-9.0.35\\\\webapps\\\\librarySystem\\\\web\\\\net\\\\bookImage\”;
//文件夹内文件数目有上限，但是可以创建子目录
//获取当前系统时间
Calendar now = Calendar.getInstance();
int year = now.get(Calendar.YEAR);
int month = now.get(Calendar.MONTH)+1;
int day = now.get(Calendar.DAY_OF_MONTH);
path = path+\”/\”+year+\”/\”+month+\”/\”+day;
//若该目录不存在，直接创建新目录
File dirFile = new File(path);
if(!dirFile.exists()){
dirFile.mkdirs();
}
//创建目标文件，用来保存上传文件
File desFile = new File(path,newFileName);
//创建文件输出流
OutputStream os = new FileOutputStream(desFile);
//将输入流数据写入到输出流中
int len=-1;
byte[]buf = new byte[1024];
while((len=is.read(buf))!=-1){
os.write(buf,0,len);
}
//desFile.delete();//删除临时文件
os.close();//输出流
is.close();//输入流
//删除临时文件
item.delete();
}
}
} catch (FileUploadException e) {
e.printStackTrace();
}
}
}