Java以struts2为例介绍如何实现图片上传

2024-07-13 09:56:05

字体：大中小

来源：转载

供稿：网友

这篇文章主要介绍了Java struts2中如何实现图片上传的相关资料,需要的朋友可以参考下

总的说图片上传有两种方式，一种是把图片文件写到数据库中，另一种是存到服务器文件目录中。写到数据库中的图片文件需要转换成二进制流的格式，占用数据库空间比较，适合少量图片的存储，比如说，系统中某些小图标，写到数据库中的优点是比较安全，不容易被用户不小心删除。

在struts2中实现(以图片上传为例)

1.FileUpload.jsp代码清单如下:

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

<%@ taglib prefix="s" uri="/struts-tags" %>

<html>

<head>

<title>The FileUplaodDemo In Struts2</title>

</head>

<body>

<s:form action="fileUpload" method="post" enctype="multipart/form-data" namespace="/">

<s:file name="myFile" label="MyFile" ></s:file>

<s:textfield name="caption" label="Caption"></s:textfield>

<s:submit label="提交"></s:submit>

</s:form>

</body>

</html>

2.ShowUpload.jsp的功能清单如下:

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

<%@ taglib prefix="s" uri="/struts-tags" %>

<html>

<head>

<title>ShowUpload</title>

</head>

<body>

<div style ="padding: 3px; border: solid 1px #cccccc; text-align: center" >

<img src ="UploadImages/<s:property value ="imageFileName"/> "/>

<br />

<s:property value ="caption"/>

</div >

</body>

</html>

3.FileUploadAction.java的代码清单如下 :

package com.chris;

import java.io.*;

import java.util.Date;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionSupport;

public class FileUploadAction extends ActionSupport{

private static final long serialVersionUID = 572146812454l ;

private static final int BUFFER_SIZE = 16 * 1024 ;

//注意，文件上传时<s:file/>同时与myFile，myFileContentType,myFileFileName绑定

//所以同时要提供myFileContentType,myFileFileName的set方法

private File myFile; //上传文件

private String contentType;//上传文件类型

private String fileName; //上传文件名

private String imageFileName;

private String caption;//文件说明，与页面属性绑定

public void setMyFileContentType(String contentType) {

System.out.println("文件类型 : " + contentType);

this .contentType = contentType;

}

public void setMyFileFileName(String fileName) {

System.out.println("文件名称 : " + fileName);

this .fileName = fileName;

}

public void setMyFile(File myFile) {

this .myFile = myFile;

}

public String getImageFileName() {

return imageFileName;

}

public String getCaption() {

return caption;

}

public void setCaption(String caption) {

this .caption = caption;

}

private static void copy(File src, File dst) {

try {

InputStream in = null ;

OutputStream out = null ;

try {

in = new BufferedInputStream( new FileInputStream(src), BUFFER_SIZE);

out = new BufferedOutputStream( new FileOutputStream(dst), BUFFER_SIZE);

byte [] buffer = new byte [BUFFER_SIZE];

while (in.read(buffer) > 0 ) {

out.write(buffer);

}

} finally {

if ( null != in) {

in.close();

}

if ( null != out) {

out.close();

}

}

} catch (Exception e) {

e.printStackTrace();

}

}

private static String getExtention(String fileName) {

int pos = fileName.lastIndexOf(".");

return fileName.substring(pos);

}

@Override

public String execute() {

imageFileName = new Date().getTime() + getExtention(fileName);

File imageFile = new File(ServletActionContext.getServletContext().getRealPath("UploadImages" ) + "/" + imageFileName);

copy(myFile, imageFile);

return SUCCESS;

}

}

注:此时仅为方便实现Action所以继承ActionSupport,并Overrider execute()方法

在struts2中任何一个POJO都可以作为Action

4.struts.xml清单如下:

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE struts PUBLIC

"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"

"http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>

<package name="example" namespace="/" extends="struts-default">

<action name="fileUpload" class="com.chris.FileUploadAction">

<interceptor-ref name="fileUploadStack"/>

<result>/ShowUpload.jsp</result>

</action>

</package>

</struts>

5.web.xml清单如下:

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.4"

xmlns="http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee

http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<filter >

<filter-name > struts-cleanup </filter-name >

<filter-class >

org.apache.struts2.dispatcher.ActionContextCleanUp

</filter-class >

</filter >

<filter-mapping >

<filter-name > struts-cleanup </filter-name >

<url-pattern > /* </url-pattern >

</filter-mapping >

<filter>

<filter-name>struts2</filter-name>

<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>

</filter>

<filter-mapping>

<filter-name>struts2</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<welcome-file-list>

<welcome-file>Index.jsp</welcome-file>

</welcome-file-list>

</web-app>