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由于项目需求，在处理文件上传时需要使用到文件的异步上传。这里使用Jquery Ajax File Uploader这个组件下载地址
服务器端采用struts2来处理文件上传。所需环境：jquery.jsajaxfileupload.jsstruts2所依赖的jar包及struts2-json-plugin-2.1.8.1.jar编写文件上传的Action package com.ajaxfile.action; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import org.apache.struts2.ServletActionContext; import com.opensymphony.xwork2.ActionSupport;@SuppressWarnings( " serial " ) public class FileAction extends ActionSupport { private File file; private String fileFileName; private String fileFileContentType; private String message = " 你已成功上传文件 " ; public String getMessage() { return message; } public void setMessage(String message) { this .message = message; } public File getFile() { return file; } public void setFile(File file) { this .file = file; } public String getFileFileName() { return fileFileName; } public void setFileFileName(String fileFileName) { this .fileFileName = fileFileName; } public String getFileFileContentType() { return fileFileContentType; } public void setFileFileContentType(String fileFileContentType) { this .fileFileContentType = fileFileContentType; } @SuppressWarnings( " deprecation " ) @Override public String execute() throws Exception { String path = ServletActionContext.getRequest().getRealPath( " /upload " ); try { File f = this .getFile(); if ( this .getFileFileName().endsWith( " .exe " )){ message = " 对不起,你上传的文件格式不允许!!! " ; return ERROR; } FileInputStream inputStream = new FileInputStream(f); FileOutputStream outputStream = new FileOutputStream(path + " / " + this .getFileFileName()); byte [] buf = new byte [ 1024 ]; int length = 0 ; while ((length = inputStream.read(buf)) != - 1 ) { outputStream.write(buf, 0 , length); } inputStream.close(); outputStream.flush(); } catch (Exception e) { e.printStackTrace(); message = " 对不起,文件上传失败了!!!! " ; } return SUCCESS; }}
struts.xml
<? xml version="1.0" encoding="UTF-8" ?> <! DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd" > < struts > < package name ="struts2" extends ="json-default" > < action name ="fileUploadAction" class ="com.ajaxfile.action.FileAction" > < result type ="json" name ="success" > < param name ="contentType" > text/html </ param > </ result > < result type ="json" name ="error" > < param name ="contentType" > text/html </ param > </ result > </ action > </ package > </ struts >
注意结合Action观察struts.xml中result的配置。
contentType参数是一定要有的，否则浏览器总是提示将返回的JSON结果另存为文件，不会交给ajaxfileupload处理。这是因为struts2 JSON Plugin默认的contentType为application/json，而ajaxfileupload则要求为text/html。
文件上传的jsp页面 <% @ page language = " java " contentType = " text/html; charset=UTF-8 " pageEncoding = " UTF-8 " %> <! DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd" > < html > < head > < meta http-equiv ="Content-Type" content ="text/html; charset=UTF-8" > < title > Insert title here </ title > < script type ="text/javascript" src ="js/jquery.js" ></ script > < script type ="text/javascript" src ="js/ajaxfileupload.js" ></ script > < script type ="text/javascript" > function ajaxFileUpload() { $( " #loading " ) .ajaxStart( function (){ $( this ).show(); }) // 开始上传文件时显示一个图片 .ajaxComplete( function (){ $( this ).hide(); }); // 文件上传完成将图片隐藏起来 $.ajaxFileUpload ( { url:'fileUploadAction.action', // 用于文件上传的服务器端请求地址 secureuri: false , // 一般设置为false fileElementId:'file', // 文件上传空间的id属性 <input type="file" id="file" name="file" /> dataType: 'json', // 返回值类型 一般设置为json success: function (data, status) // 服务器成功响应处理函数 { alert(data.message); // 从服务器返回的json中取出message中的数据,其中message为在struts2中action中定义的成员变量 if ( typeof (data.error) != 'undefined') { if (data.error != '') { alert(data.error); } else { alert(data.message); } } }, error: function (data, status, e) // 服务器响应失败处理函数 { alert(e); } } ) return false ; } </ script > </ head > < body > < img src ="loading.gif" id ="loading" style ="display: none;" > < input type ="file" id ="file" name ="file" /> < br /> < input type ="button" value ="上传" onclick ="return ajaxFileUpload();" > </ body > </ html >
注意观察<body>中的代码，并没有form表单。只是在按钮点击的时候触发ajaxFileUpload()方法。需要注意的是js文件引入的先后顺序，ajaxfileupload.js依赖于jquery因此你知道的。