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java中struts2实现文件上传下载功能

作者：GYW　　发布时间：2021-11-16 19:53:47　

标签：Struts2,上传,下载

先谈一谈struts2实现文件的上传和下载实例实现的原理：

Struts 2是通过Commons FileUpload文件上传。

Commons FileUpload通过将HTTP的数据保存到临时文件夹，然后Struts使用fileUpload * 将文件绑定到Action的实例中。从而我们就能够以本地文件方式的操作浏览器上传的文件。

具体实现：

一、创建index.jsp页面

<body>
<s:form action="upload" method="post" theme="simple" enctype="multipart/form-data">
<table align="center" width="50％" border="1">
<tr>
<td>选择上传文件</td>
<td id="more">
<s:file name="file"></s:file>
<input type="button" value="Add More.." onclick="addMore()">
</td>
</tr>
<tr>
<td><s:submit type="button" value="submit" onclick="return checkf()"/></td>
<td><s:reset value="reset "></s:reset></td>
</tr>
</table>
<table align="center" width="50％" border="1">
<tr>
<td>测试.txt</td>
<td>
<a href="<s:url value='download.action'><s:param name='fileName'>测试.txt</s:param> </s:url>">下载</a>
</td>
</tr>
</table>
</s:form>
</body>

创建result.jsp页面

<body>
<s:form>
<div style="border:1px solid black">成功上传的文件:<br>
<ul style="list-style-type:decimal">
<s:iterator value="#request.fileName" id="file" status="status">
<li><s:property/> </li>
</s:iterator>
</ul>
</div>
</s:form>
</body>

当然别忘了在每个页面上都添加上struts2 标签引用<％@taglib prefix="s" uri="/struts-tags" ％>

二、创建updown.js文件，在index.jsp中引用

function checkf(){
var files = document.getElementsByName("file");
if(files[0].value.length!=0){
return true;
}else{
alert("请选择文件");
return false;
}
}
function addMore()
{
var td = document.getElementById("more");
var br = document.createElement("br");
var input = document.createElement("input");
var button = document.createElement("input");
input.type = "file";
input.name = "file";
button.type = "button";
button.value = "Remove";
button.onclick = function()
{
td.removeChild(br);
td.removeChild(input);
td.removeChild(button);
}
td.appendChild(br);
td.appendChild(input);
td.appendChild(button);
}

三、创建upDownloadAction.java

package com.action;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import com.opensymphony.xwork2.ActionSupport;
import org.apache.struts2.ServletActionContext;

public class UpDownloadAction extends ActionSupport {

private static final long serialVersionUID = 1L;
private List<File> file;// 对应jsp中file标签
private List<String> fileFileName;//
private List<String> fileContentType;//
private String fileName;//获得jsp中pram参数
@SuppressWarnings("deprecation")
// 文件上传
public String uploadFiile() throws Exception {
String root = ServletActionContext.getServletContext().getRealPath(
"/upload");// 上传路径
System.out.println(root);
InputStream inputStream;
File destFile;
OutputStream os;
for (int i = 0; i < file.size(); i++) {
inputStream = new FileInputStream(file.get(i));
destFile = new File(root, this.getFileFileName().get(i));
os = new FileOutputStream(destFile);
byte[] buffer = new byte[400];
int length = 0;
while ((length = inputStream.read(buffer)) > 0) {
os.write(buffer, 0, length);
}
inputStream.close();
os.close();
}
HttpServletRequest request = ServletActionContext.getRequest();
request.setAttribute("fileName", fileFileName);
return SUCCESS;
}

// 文件下载
public InputStream getDownloadFile() throws FileNotFoundException,
UnsupportedEncodingException {
System.out.println(getFileName());

// 如果下载文件名为中文，进行字符编码转换
ServletActionContext.getResponse().setHeader("Content-Disposition","attachment;fileName="
+ java.net.URLEncoder.encode(fileName, "UTF-8"));
InputStream inputStream = new FileInputStream("F:/" //使用绝对路径，从该路径下载“测试.txt"文件
+ this.getFileName());
System.out.println(inputStream);
return inputStream;
}

// 下载
public String downloadFile() throws Exception {
return SUCCESS;
}

public String getFileName() throws UnsupportedEncodingException {
return fileName;
}

public void setFileName(String fileName)
throws UnsupportedEncodingException {
this.fileName = new String(fileName.getBytes("ISO8859-1"), "utf-8");
}
}

注：属性的 get和set方法已省略。

四、最后是配置文件

1、web.xml配置

<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>

2、struts.xml配置

<struts>
<constant name="struts.i18n.encoding" value="utf-8"></constant>
<constant name="struts.multipart.saveDir" value="f:\"></constant>
<package name="struts2" extends="struts-default">
<action name="upload" class="com.action.UpDownloadAction" method="uploadFiile">
<result name="success">/jsp/result.jsp</result>
<interceptor-ref name="fileUpload">

<param name="maximumSize">409600</param>

<param name="allowedTypes">
text/plain
</param>
</interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
</action>
<action name="download" class="com.action.UpDownloadAction" method="downloadFile" >
<result name="success" type="stream">

<param name="contentType">
application/txt;
</param>


<param name="contentDisposition">
attachment;filename="${fileName}"
</param>

<param name="inputName">downloadFile</param>

<param name="bufferSize">2048</param>
</result>
</action>
</package>
</struts>

一个简单的Struts2多文件上传和单文件下载就实现了。

投稿

java中struts2实现文件上传下载功能

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