本博文主要说，用户如何更换头像的操作

1.首先要有一个util的工具类(直接用就可以)上传文件需要的jar包，在最下方。

package com.hp.factory;

import java.io.File;

import java.io.IOException;

import java.util.Iterator;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;

import org.apache.commons.fileupload.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class FileUploadUtil {

//文件接收

private static final long serialVersionUID = -4187075130535308117L;

private boolean isMultipart;

private int maxFileSize = 1024 * 1024 * 10;

private int maxMemSize = 100 * 1024;

private static FileUploadUtil fu = null;

public static FileUploadUtil getFu() {

if(fu == null) {

fu = new FileUploadUtil();

}

return fu;

}

public String upload(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// 检查是否有一个文件上传请求

isMultipart = ServletFileUpload.isMultipartContent(request);

String result = "";

if (!isMultipart) {

result = "not_found";

return result;

}

DiskFileItemFactory factory = new DiskFileItemFactory();

// 文件大小的最大值将被存储在内存中

factory.setSizeThreshold(maxMemSize);

//path是下载到的地址

String path = "D:\\Tomcat-9\\apache-tomcat-9.0.34\\webapps\\hui\\";  //

factory.setRepository(new File(path));

//System.out.println(path);

// 创建一个新的文件上传处理程序

ServletFileUpload upload = new ServletFileUpload(factory);

// 允许上传的文件大小的最大值

upload.setSizeMax(maxFileSize);

try {

// 解析请求，获取文件项

List fileItems = upload.parseRequest(request);

// 处理上传的文件项

Iterator i = fileItems.iterator();

while (i.hasNext()) {

FileItem fi = (FileItem) i.next();

if (!fi.isFormField()) {

// 获取上传文件的参数

String fieldName = fi.getFieldName();

String fileName = fi.getName();

String contentType = fi.getContentType();

boolean isInMemory = fi.isInMemory();

long sizeInBytes = fi.getSize();

// 写入文件

path = path + System.currentTimeMillis() / 1000 + ".jpg";

File file = new File(path);

fi.write(file);

}

}

result = path;

} catch (Exception ex) {

System.out.println("ex:" + ex.getMessage());

result = "error";

}

return result;

}

}

2.jsp页面头像的修改(表单提交)

	修改

3.servlet类，这里写入到了post里面

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

String str = FileUploadUtil.getFu().upload(request, response);  //调用了util工具类

if(str.equals("not_found")) {//不是文件上传

//response.getWriter().write("error");

}else if(str.equals("error")) {//上传失败

//response.getWriter().write("errore");

}else {

//把路径存数据库去，然后前台读取

String adminLoad = str.replace('\\','/').substring(40);//这里是,替换并分割出来,替换的是转义符,分割的是webapps的目录一下的目录(这里不包括webapps)

String adminName = (String) request.getSession().getAttribute("adminName");     //这里是我要修改的用户的账号

try {

managerDao.adminLoad(adminLoad, adminName);  //这里是修改头像在mysql中的字段

response.sendRedirect("/project01/login.jsp");//修改成功跳转的地址

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

4.jsp页面展示的语句

//src="${adminLoad}" 是我们登录成功时，直接request.getSession().setAttribute("adminLoad", img);

链接https://pan.baidu.com/s/19UCxPr5rq2c0y7bB1Omjwg 提取码：nubu

上面的内容有什么不对的地方，请大家多多指教！