如何在struts2中实现下载?

<a href="${pageContext.request.contextPath}/download?filename="+filename>点击下载</a>

在action类中执行完execute方法后返回成功字符串跳转到result之后再result中设置contentType、contentDisposition、inputStream

<result name="success" type="stream">
　　<param name="contentType">${contentType}</param>
　　<param name="contentDisposition">attchment;filename=${downloadFileName}</param>

　　<param name="inputStream">${inputStream}</param>

</result>

在action类中提供对应的getContentType、getDownloadFileName、getInputStream方法

public String getContentType() {

　　String mimeType = ServletActionContext.getServletContext().getMimeType(filename);
　　return mimeType;

}

public String getDownloadFileName() throws UnsupportedEncodingException {

　　return DownloadUtils.getDownloadFileName(ServletActionContext.getRequest().getHeader("user-agent"), filename);

}

public InputStream getInputStream() throws FileNotFoundException,UnsupportedEncodingException {

　　filename = new String(filename.getBytes("iso8859-1"), "utf-8"); // 解决中文名称乱码.

　　FileInputStream fis = new FileInputStream("d:/upload/" + filename);
　　return fis;
}

用DownloadUtils工具类来返回一个下载文件名，目的之为了去支持不同的浏览器，比如火狐用的是BASE64编码

public class DownloadUtils {

    public static String getDownloadFileName(String agent,String filename) throws UnsupportedEncodingException{
        if(agent.contains("MSIE")){
            //IE
            filename = URLEncoder.encode(filename,"utf-8");
        }else if(agent.contains("Firefox")){
            //火狐浏览器
            BASE64Encoder base64Encoder = new BASE64Encoder();
            filename = "=?utf-8?B?" + base64Encoder.encode(filename.getBytes("utf-8")) + "?=";
        }else{
            //其他浏览器
            filename = URLEncoder.encode(filename,"utf-8");
        }
        return filename;
    }
    
}