文件下载

1.后台代码

package com.jcsoft.transaction.common.action;

import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @Class: DownloadAction.java
 * @Description: 文件下载Action
 * @Author：lvm
 * @Date：2013-8-15
 */
public class DownloadAction extends BaseAction {
    private static final long serialVersionUID = -7687893505332784649L;

    private static String LOCATION_FILE_URL = "c://temp/"; // 创建本地磁盘文件夹路径
    private String fileName; // 下载文件名称，输出到用户的下载对话框
    private String filePath; // 下载文件URL（绝对路径）

    public String execute() {
        return "success";
    }

    /**
     * @Author：lvm
     * @Description: 获取下载文件输入流
     * @Date：2013-8-15 下午2:07:54
     * @Return：InputStream
     */
    public InputStream getInputStream() throws Exception {
        // 如果目录存在,先删除目录下的所有文件，反之则创建目录
        File ufile = new File(LOCATION_FILE_URL);
        boolean flag = false;
        if (ufile.exists() == true) {
            // 删除文件夹下的所有文件(包括子目录)
            File[] files = ufile.listFiles();
            for (int i = 0; i < files.length; i++) {
                // 删除子文件
                if (files[i].isFile()) {
                    flag = deleteFile(files[i].getAbsolutePath());
                    if (!flag)
                        break;
                }
            }
        } else {
            ufile.mkdir();
        }

        // 从下载文件绝对路径中提取文件名，并进行编码转换，防止不能正确显示中文名
        if (this.filePath.lastIndexOf("/") > 0) {
            this.fileName = new String(this.filePath.substring(
                    this.filePath.lastIndexOf("/") + 1, this.filePath.length())
                    .getBytes("GB2312"), "ISO8859_1");
        } else if (this.filePath.lastIndexOf("\") > 0) {
            this.fileName = new String(this.filePath
                    .substring(this.filePath.lastIndexOf("\") + 1,
                            this.filePath.length()).getBytes("GB2312"),
                    "ISO8859_1");
        }

        // 下载文件流
        File dfile = getFileFromBytes(this.filePath, LOCATION_FILE_URL
                + new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date())
                + ".temp");
        InputStream is = new FileInputStream(dfile); // 绝对路径下载
        return is;
    }

    /**
     * @Author：lvm
     * @Description: 把字节数组保存为一个文件
     * @Date：2013-8-15 下午2:23:07
     * @Return：File
     */
    public File getFileFromBytes(String fileUrl, String outputFile) {
        BufferedOutputStream stream = null;
        File file = null;
        try {
            file = new File(outputFile);
            FileOutputStream fstream = new FileOutputStream(file);
            stream = new BufferedOutputStream(fstream);
            stream.write(getUrlFileData(fileUrl));
        } catch (Exception e) {
            log.error(e.getMessage(), e);
        } finally {
            if (stream != null) {
                try {
                    stream.close();
                } catch (IOException e1) {
                    log.error(e1.getMessage(), e1);
                }
            }
        }
        return file;
    }

    /**
     * @Author：lvm
     * @Description: 获取链接地址文件的byte数据
     * @Date：2013-8-15 下午2:20:35
     * @Return：byte[]
     */
    public byte[] getUrlFileData(String fileUrl) throws Exception {
        URL url = new URL(fileUrl);
        HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
        httpConn.connect();
        InputStream cin = httpConn.getInputStream();
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = 0;
        while ((len = cin.read(buffer)) != -1) {
            outStream.write(buffer, 0, len);
        }
        cin.close();
        byte[] fileData = outStream.toByteArray();
        outStream.close();
        return fileData;
    }

    /**
     * @Author：lvm
     * @Description: 删除文件
     * @Date：2013-8-15 下午2:19:51
     * @Return：boolean
     */
    public boolean deleteFile(String sPath) {
        boolean flag = false;
        // 路径为文件且不为空则进行删除
        File file = new File(sPath);
        if (file.isFile() && file.exists()) {
            file.delete();
            flag = true;
        }
        return flag;
    }

    public String getFileName() {
        return fileName;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

    public String getFilePath() {
        return filePath;
    }

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

2.struts配置

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
    <package name="uploadpackage" namespace="/" extends="json-default,app-interceptors">
        <!-- 图片上传 -->                         
        <action name="upload" class="com.jcsoft.transaction.upload.action.uploadAction" >
            <result type="json">
                <param name="root">jsonMap</param>
            </result>
        </action>
        <!-- 文件下载 -->
        <action name="download" class="com.jcsoft.transaction.common.action.DownloadAction">
           <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">10240000</param>
           </result>
        </action>
    </package>
    
</struts>

3.前端请求代码

window.location.href = "/download!execute.do?filePath=https://gss0.baidu.com/94o3dSag_xI4khGko9WTAnF6hhy/zhidao/pic/item/a8773912b31bb05158c8e052327adab44bede0d8.jpg";