java文件上传--基于ajaxFileUpload+struts2

jQuery插件ajaxFileUpload可以实现ajax文件上传，使用非常简单。
下面做一个简单的demo(以上传图片为例)，实现图片上传，图片显示，图片下载

注：以下的代码是在项目的基础上进行开发。css样式文件、包路径等未做修改。
1、 ajaxFileUpload文件下载地址http://www.phpletter.com/Demo/AjaxFileUpload-Demo/
2、自行引入jquery.js、ajaxFileUpload.js文件
jsp核心代码：
<script type="text/javascript">
function fileUpload() {
$.ajaxFileUpload( {
url : 'admin/fileAction.do',//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) {
$("#downImg").show(); //待上传成功后 显示下载按钮
$("#downImg").attr("href","admin/downloadImage.do?filePath="+data.filePath);
$("#showImg").attr("src","admin/redImage.do?path=" + data.filePath);
}
})
}
</script>
<table class="editTable">
<tr>
<td colspan="4">
<img id="showImg" alt="" src="">
<a id="downImg" style="display: none" href="">下载</a>
</td>
</tr>
<tr>
<td class="title">
上传图片:
</td>
<td colspan="3">
<input type="file" id="file" name="file" onchange="fileUpload();">
</td>
</tr>
</table>
3、AjaxFileUploadAction
public class AjaxFileUploadAction extends WebSupport {

private File file; //文件
private String fileFileName; //文件名
private String filePath; //文件路径
private InputStream inputStream;

/**
* 图片上传
*
* @return
*/
public String fileUpload() {
String path = ServletActionContext.getServletContext().getRealPath("/upload");
File file = new File(path); // 判断文件夹是否存在,如果不存在则创建文件夹
if (!file.exists()) {
file.mkdir();
}
try {
if (this.file != null) {
File f = this.getFile();
String fileName = java.util.UUID.randomUUID().toString(); // 采用时间+UUID的方式随即命名
String name = fileName+ fileFileName.substring(fileFileName.lastIndexOf(".")); // 保存在硬盘中的文件名

FileInputStream inputStream = new FileInputStream(f);
FileOutputStream outputStream = new FileOutputStream(path+ "\\" + name);
byte[] buf = new byte[1024];
int length = 0;
while ((length = inputStream.read(buf)) != -1) {
outputStream.write(buf, 0, length);
}
inputStream.close();
outputStream.flush();
//文件保存的完整路径 比如：D:\tomcat6\webapps\eserver\\upload\a0be14a1-f99e-4239-b54c-b37c3083134a.png
filePath = path+"\\"+name;

}
} catch (Exception e) {
e.printStackTrace();
}
return SUCCESS;
}

/**
* 用于图片页面显示
*
* @return
*/
public String readImg() {
try {
inputStream = new FileInputStream(new File(getRequest().getParameter("path")));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return SUCCESS;
}
/**
* 图片下载
* @return
*/
public String download() {
String path = filePath;
HttpServletResponse response = ServletActionContext.getResponse();
try {
// path是指欲下载的文件的路径。
File file = new File(path);
// 取得文件名。
String filename = file.getName();
// 取得文件的后缀名。
String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();
// 以流的形式下载文件。
InputStream fis = new BufferedInputStream(new FileInputStream(path));
byte[] buffer = new byte[fis.available()];
fis.read(buffer);
fis.close();
//清空response
response.reset();
//设置response的Header
String filenameString = new String(filename.getBytes("gbk"),"iso-8859-1");
response.addHeader("Content-Disposition", "attachment;filename=" + filenameString);
response.addHeader("Content-Length", "" + file.length());
OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
response.setContentType("application/octet-stream");
toClient.write(buffer);
toClient.flush();
toClient.close();
} catch (IOException ex) {
ex.printStackTrace();
}
return null;
}

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 getFilePath() {
return filePath;
}

public void setFilePath(String filePath) {
this.filePath = filePath;
}

public InputStream getInputStream() {
return inputStream;
}

public void setInputStream(InputStream inputStream) {
this.inputStream = inputStream;
}

private static final Logger log = Logger
.getLogger(AjaxFileUploadAction.class);
private static final long serialVersionUID = 1L;
}
4、struts配置
<struts>
<package name="struts_Ajax_code" extends="json-default">
<!-- 文件上传 -->
<action name="fileAction" class="com.bk.eserver.web.action.AjaxFileUploadAction" method="fileUpload">
<result type="json" name="success">
<param name="contentType">text/html</param>
</result>
</action>
</package>
<package name="struts_Jsp_code" extends="struts-default">
<!-- 图片读取 -->
<action name="redImage" class="com.bk.eserver.web.action.AjaxFileUploadAction" method="readImg">
<result type="stream">
<param name="contentType">application/octet-stream</param>
<param name="inputName">inputStream</param>
<param name="contentDisposition">attachment;filename=${fileName}</param>
<param name="bufferSize">4096</param>
</result>
</action>
<!-- 文件下载 -->
<action name="downloadImage" class="com.bk.eserver.web.action.AjaxFileUploadAction" method="download">
<result type="stream">
<param name="contentType">application/octet-stream</param>
<param name="inputName">inputStream</param>
<param name="contentDisposition">attachment;filename=${fileName}</param>
<param name="bufferSize">4096</param>
</result>
</action>
</package>
</struts>