Struts2

<action name="download" class="action.netDiskAction.DownloadAction">
            <!-- 文件名 -->
            <param name="fileName"></param>
            <result name="success" type="stream">
                <!-- 类型-->
                <param name="contentType">text/plain</param>
                <!-- 前台链接参数 -->
                <param name="contentDisposition">attachment;filename="${downloadChineseFileName}"</param>
                <param name="inputName">downloadFile</param>
            </result>
            <result name="downloaderror" type="chain">showResList</result>
        </action>

import java.io.File;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;
 
/**
 * 个人中心资源问答下载附件实现
 */
public class DownloadAction extends ActionSupport {
    private String fileName; // 文件名和文件路径
    private String newFileName; // 用于下载后显示的文件名
    private boolean isExists; // 用户判断文件是否存在
    private int toPage; // 下载资源所在的当前页面
 
    // 从下载文件原始存放路径读取得到文件输出流
    public InputStream getDownloadFile() {
        return ServletActionContext.getServletContext().getResourceAsStream("/" + fileName);
    }
 
    // 如果下载文件名为中文，进行字符编码转换
    public String getDownloadChineseFileName() {
        String downloadChineseFileName = newFileName;
        try {
            downloadChineseFileName = new String(downloadChineseFileName.getBytes(), "ISO8859-1");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return downloadChineseFileName;
    }

public String execute() {
        String basePath = ServletActionContext.getServletContext().getRealPath("");
        String filePath = basePath + fileName;
        File file = new File(filePath);
        if (!file.exists()) {
            HttpServletRequest request = ServletActionContext.getRequest();
            request.setAttribute("message", "文件已经不存在，请联系管理员！");
            // 如果topage为0时，说明在第一页，需要进行重新设置为1
            if (toPage == 0) {toPage = 1;}
            return "downloaderror";
        } else {
            return SUCCESS;
        }
    }
    public String getFileName() {return fileName;}
    public void setFileName(String fileName) {this.fileName = fileName;}
    public String getNewFileName() {return newFileName;}
    public void setNewFileName(String newFileName) {this.newFileName = newFileName;}
    public int getToPage() {return toPage;}
    public void setToPage(int toPage) {this.toPage = toPage;}
}