接上篇Struts2使用註解實現文件的上傳與下載（一），這次介紹使用註解實現文件下載，基本配置與之前的一樣，這裏重點講下載的Action寫法。
文件下載的Action：DownloadAction.java
package com.figo.action;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import org.apache.commons.io.FileUtils;
import org.apache.struts2.ServletActionContext;
import org.apache.struts2.convention.annotation.ParentPackage;
import org.apache.struts2.convention.annotation.Results;
import org.apache.struts2.convention.annotation.Result;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;
import com.opensymphony.xwork2.Validateable;
import com.opensymphony.xwork2.ValidationAwareSupport;
/**
* 所下載文件相關的的幾個屬性:文件格式 contentType,
* 獲取文件名的方法inputName,
* 文件內容（顯示的）屬性contentDisposition,
* 限定下載文件 緩衝區的值bufferSize
* */
@Results({ @Result(name = "success", type = "stream", params = { "contentType",
"application/octet-stream;charset=ISO8859-1", "inputName",
"inputStream", "contentDisposition",
"attachment;filename=\"Readme.txt\"", "bufferSize", "4096" }) })
public class DownloadAction extends ActionSupport {
private static final long serialVersionUID = 8784555891643520648L;
private String STORAGEPATH = "/upload/Readme.txt";
private String fileName;// 初始的通過param指定的文件名屬性
private String storageId;
private String inputPath;// 指定要被下載的文件路徑
public String getFileName() {
return fileName;
}
public void setFileName(String fileName) {
this.fileName = fileName;
}
public void setInputPath(String inputPath) {
this.inputPath = inputPath;
}
public String getStorageId() {
return storageId;
}
public void setStorageId(String storageId) {
this.storageId = storageId;
}
// 如果下載文件名爲中文，進行字符編碼轉換
public String getDownloadFileName() {
String downloadFileName = fileName;
try {
downloadFileName = new String(downloadFileName.getBytes(),
"ISO8859-1");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return downloadFileName;
}
public InputStream getInputStream() throws Exception {
/**
* 下載用的Action應該返回一個InputStream實例，
* 該方法對應在result裏的inputName屬性值爲targetFile
**/
return ServletActionContext.getServletContext().getResourceAsStream(
STORAGEPATH);
}
public String execute() throws Exception {
return SUCCESS;
}
}
代碼其實很簡單，最關鍵的就是getInputStream()方法，返回一個InputStream實例，還有就是@Results的配置。
測試頁面：download.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Download</title>
</head>
<body>
<s:a href="download.action">Download</s:a>
</body>
</html>結果如下：
