用Struts2+Dojo实现文件下载
介绍
Struts2 + Dojo是目前非常通用的Web应用开发组合。文件下载则是非常老的一个功能了。现在就介绍一下如何用Struts2+ Dojo 1.7.3实现文件下载的功能。
前端：初始化Dojo，创建下载按钮，实现点击下载事件
test.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<style type="text/css">
@import "../js/dijit/themes/tundra/tundra.css";
@import "../css/main.css";
</style>
</head>
<body class="tundra">
<button id="download_btn" data-dojo-type="dijit.form.Button"
class="menu_button" type="button">下载文件</button>
<script>
dojoConfig = {
isDebug : false,
parseOnLoad : true,
async : true
};
</script>
<script type="text/javascript" src="../js/dojo/dojo.js"></script>
<script>
require([ "dojo/parser", "dijit/form/Button"]);
</script>
<script>
require(
[ "dojo/ready",
"dijit/registry",
"dojo/dom",
"dojo/on",
"dojo/io/iframe"
],
function(ready, registry, dom, on) {
ready(function() {
on(registry.byId("download_btn"), "click", function(e){
var exportIframeName = "downloadPdfIframe";
var iframe = dojo.io.iframe.create(exportIframeName);
var url = "download.action";
dojo.io.iframe.setSrc(iframe, url, true);
});
});
});
</script>
</body>
</html>
后端：配置下载请求
struts.xml
<action name="download" class="test.servlet.DownloadAction">
<result name="success" type="stream">
<param name="contentType">text/plain</param>
<param name="inputName">inputStream</param>
<param name="contentDisposition">
attachment;filename="${filename}.xml"
</param>
<param name="bufferSize">2048</param>
</result>
</action>
后端：实现下载
DownloadAction.java
package test.servlet;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import org.apache.commons.io.FileUtils;
import com.opensymphony.xwork2.ActionSupport;
public class DownloadAction extends ActionSupport {
private static final long serialVersionUID = 1L;
private String filename;
private InputStream inputStream;
public String execute() {
String xml;
try {
xml = FileUtils.readFileToString(new File("c:\test.xml"), "UTF-8");
} catch (IOException e) {
return ERROR;
}
filename = "test";
try {
inputStream = new ByteArrayInputStream(xml.getBytes("UTF-8"));
} catch (UnsupportedEncodingException e) {
return ERROR;
}
return SUCCESS;
}
public String getFilename() {
return filename;
}
public void setFilename(String filename) {
this.filename = filename;
}
public InputStream getInputStream() {
return inputStream;
}
public void setInputStream(InputStream inputStream) {
this.inputStream = inputStream;
}
}
总结
上面的实现有两个关键点。一个就是用Dojo来实现客户端的文件下载功能。这儿首先要用dojo.io.iframe.create创建一个iframe，然后将这个iframe传给dojo.io.iframe.setSrc，并设置正确的URL。另外一个关键的地方是后台struts.xml和Action.java的配合。struts.xml中两个属性inputName和contentDisposition中的内容必须要和Action.java中的变量对应。而result的type设置为stream。