本次文件依靠第三方组件(Apache)进行实现
commons-fileupload组件：
commons-fileupload.jar
jar包下载地址： http://commons.apache.org/proper/commons-fileupload/download_fileupload.cgi 操作指南： http://commons.apache.org/proper/commons-fileupload/using.html
commons-io.jar
jar包下载地址： http://commons.apache.org/proper/commons-io/download_io.cgi 操作指南： http://commons.apache.org/proper/commons-io/description.html
1.form表单的method必须是post
2.form表单的组件得是file属性：比如:<input type="file" name="photoName" >
3.form表单的enctype必须是multipart/form-data 以二进制字节流进行提交 传统接收参数的方式无效
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE>
<html>
<head>
<title>MrYang Design File Upload</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/servlet/UploadServlet" enctype="multipart/form-data" method="post" >
名称<input type="text" name="name" ><br/><br/>
密码<input type="text" name="pwd" ><br/><br/>
<input type="file" name="photoName" ><br/><br/>
<input type="submit" value="上传" >
</form>
</body>
</html>
2.servlet中进行接受并且进行上传处理
package cn.javabs.web.controller;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
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 org.apache.commons.io.FilenameUtils;
import cn.javabs.exception.MyFileUploadException;
public class UploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@SuppressWarnings("unchecked")
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/**
* Set CharEncoding
*/
response.setContentType("text/html ;charset = utf-8 ");
response.setCharacterEncoding("utf-8");
request.setCharacterEncoding("utf-8");
// 1. 用于判断jsp表单中的enctype 的属性值是不是multipart/form-data
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
// 如果不是multipart/form-data 则提醒
if (!isMultipart) {
response.getWriter().write("提交的不是multipart/form-data");
return;
}
//实例化 磁盘文件项工厂对象
DiskFileItemFactory factory = new DiskFileItemFactory();
//ServletFileUpload是用于解析request对象
ServletFileUpload upload = new ServletFileUpload(factory);
List<FileItem> items = null;
try {
// 通过ServletFileUpload得到所有上传项.每一个FileItem就相当于一个上传项
items = upload.parseRequest(request);
} catch (FileUploadException e) {
throw new RuntimeException(e);
}
System.out.println("我们来一起看一下items是:" + items);
// 循环取出所有的组件 其中组件包含有 普通组件 和 上传组件
for (FileItem item : items) {
// 通过判断确定 item中的普通组件 使用的判断方法是isFormField
// 是普通的表单字段
if(item.isFormField()){
System.out.println("这是普通的表单字段");
// 获取表单中的属性
String fieldName = item.getFieldName();
// 获取表单中的属性所对应的值
String fieldValue = item.getString();
System.out.println(fieldName +":" + fieldValue);
}
// 是上传的表单字段
else{
System.out.println("这是上传的表单字段");
// 获取上传文件的名称
String uploadName = item.getName();
// 判断上传文件的名称是否为null,如果不为空
if(uploadName != null){
// 文件名称 = 获取文件名称，并且包含后缀
uploadName = FilenameUtils.getName(uploadName);
}
// 文件存放的真实路径 其实files文件夹 存放在Tomcat服务器的项目里面
String filePath = getServletContext().getRealPath("/files");
// 根据真实的路径 进行实例化创建目录
File file = new File(filePath);
// 如果目录不存在
if(!file.exists()){
//创建多级目录
file.mkdirs();
}
// 根据 真实目录 + "" + 文件名称 [file.separator 的结果是 ""]
try {
item.write(new File(filePath + file.separator + uploadName));
} catch (Exception e) {
throw new MyFileUploadException(e);
}
}
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
3.其中涉及到一个自定义的异常
package cn.javabs.exception;
public class MyFileUploadException extends RuntimeException {
public MyFileUploadException() {
}
public MyFileUploadException(String message) {
super(message);
}
public MyFileUploadException(Throwable cause) {
super(cause);
}
public MyFileUploadException(String message, Throwable cause) {
super(message, cause);
}
public MyFileUploadException(String message, Throwable cause,
boolean enableSuppression, boolean writableStackTrace) {
super(message, cause, enableSuppression, writableStackTrace);
}
}
4别忘了还有web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<display-name></display-name>
<servlet>
<servlet-name>UploadServlet</servlet-name>
<servlet-class>cn.javabs.web.controller.UploadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UploadServlet</servlet-name>
<url-pattern>/servlet/UploadServlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>