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Struts2文件上傳以及空指針異常解決

Posted on 2009-09-27 08:54 saobaolu 閱讀(4346) 評論(2) 編輯收藏所屬分類: java基礎與算法

uploadFile.java

package action;
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import java.io.File;
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import java.text.DateFormat;
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import java.text.SimpleDateFormat;
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import java.util.Date;
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import java.util.Random;
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import javax.servlet.ServletContext;
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import org.apache.commons.io.FileUtils;
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import org.apache.struts2.util.ServletContextAware;
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import com.opensymphony.xwork2.ActionSupport;
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public class uploadFile extends ActionSupport implements ServletContextAware {
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private static final long serialVersionUID = -5016873153441103539L;
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private File doc;
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private String fileName;
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private String contentType;
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private ServletContext context;
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public void setDoc(File file) {
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this.doc = file;
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}
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public void setDocFileName(String fileName) {
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this.fileName = fileName;
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}
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public void setDocContentType(String contentType) {
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this.contentType = contentType;
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}
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public void setServletContext(ServletContext context) {
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this.context = context;
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}
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public String execute() throws Exception {
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String targetDirectory = context.getRealPath("/upload");
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String targetFileName = generateFileName(fileName);
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File target = new File(targetDirectory, targetFileName);
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FileUtils.copyFile(doc, target);
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return SUCCESS;
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}
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private String generateFileName(String fileName) {
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DateFormat format = new SimpleDateFormat("yyMMddHHmmss");
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String formatDate = format.format(new Date());
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int random = new Random().nextInt(10000);
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int position = fileName.lastIndexOf(".");
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String extension = fileName.substring(position);
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return formatDate + random + extension;
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}
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}
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struts.xml

<?xml version="1.0" encoding="UTF-8" ?>
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<!DOCTYPE struts PUBLIC
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"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
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"http://struts.apache.org/dtds/struts-2.0.dtd">
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<struts>
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<package name="uploadFile" extends="struts-default">
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<action name="uploadFile" class="action.uploadFile">
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<result>/jsp/up.jsp</result>
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</action>
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</package>
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</struts>

web.xml(Struts2的xml，非上傳的xml)

<?xml version="1.0" encoding="UTF-8"?>
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<web-app version="2.4"
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xmlns="http://java.sun.com/xml/ns/j2ee"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
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http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
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<filter>
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<filter-name>struts2</filter-name>
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<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
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</filter>
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<filter-mapping>
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<filter-name>struts2</filter-name>
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<url-pattern>/*</url-pattern>
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</filter-mapping>
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</web-app>

up.jsp（上傳成功頁面）

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
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<%@ taglib prefix="s" uri = "/struts-tags" %>
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<%
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String path = request.getContextPath();
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String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
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%>
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<base href="<%=basePath%>">
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<title>My JSP 'up.jsp' starting page</title>
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<!--
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-->
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</head>
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<body>
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<s:property value="contentType"/><br />
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<s:property value="dir" /><br />
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</body>
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</html>
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上傳頁面：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
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<%@ taglib prefix="s" uri="/struts-tags" %>
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<%
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String path = request.getContextPath();
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String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
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%>
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<base href="<%=basePath%>">
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<title>最新產品發布頁</title>
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<!--
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-->
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</head>
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<body>
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<s:form action="uploadFile" method="post" enctype="multipart/form-data">
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<s:file name = "doc" label="上傳視頻" />
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<s:submit value="上傳" />
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</s:form>
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</body>
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</html>
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很容易就會報錯，空指針異常。
原因在于上傳頁面<s:file name="這里面的值與action的值不匹配" />
可是我上傳成功之后，up.jsp頁面沒有傳入任何值，郁悶了～
新手，多指點指點，謝謝～

沒有所謂的命運，只有不同的選擇！

騷包路技術菜

Struts2文件上傳以及空指針異常解決

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