struts2下載文件功能（邊下載邊打包）

多個文件，目錄不同，通過條件查詢如何進行打包下載呢？

1.利用ZipEntry進i行文件的壓縮

2.前臺jsp傳入需要打包下載的一系列的文件的路徑（數組類型）。因爲是在checkBox中，表單提交會自動將其定義成數組。只需要將name名稱命名成後臺需要得到的路徑數組名稱

比如前臺

downLoadZip.jsp

--------checkBox處代碼-------------------------------

利用iterator迭代出來的filePath

<input type="checkbox" name="downLoadPaths"
value='<s:property value="filePath"/>'/>

後臺Action

private String[] downLoadPaths;

對downLoadPaths進行遍歷，打包。。。。

代碼：

/**
 * 批量下載（壓縮成zip，然後下載）。不創建臨時文件
 *
 * @author Cloudy
 *
 */
@Namespace("xxxxxx")
public class DownZipAction {
    /**
     *
     */
    private static final long serialVersionUID = 1L;
    // 傳遞一個List<String>()對象傳值路徑合集
    private String[] downLoadPaths;
    private OutputStream res;
    private ZipOutputStream zos;
    private String outPath;

    // Action主方法
    @Action(value="DownLoadZip",results={@Result(name="nodata",location="/error.jsp"),
            @Result(name="success",location="xxxx.jsp")})
    public String downLoadZip() throws Exception {
        // 有數據可以下載
        if (downLoadPaths.length != 0) {
            // 進行預處理
            preProcess();
        } else {
            // 沒有文件可以下載，返回nodata
            return "nodata";
        }
        // 處理
        writeZip(downLoadPaths);
        // 後處理關閉流
        afterProcess();
        return SUCCESS;
    }

    // 壓縮處理
    public void writeZip(String[] downLoadPaths) throws IOException {
        byte[] buf = new byte[8192];
        int len;

        for (String filename : downLoadPaths) {
            File file = new File(filename);
            if (!file.isFile())
                continue;
            ZipEntry ze = new ZipEntry(file.getName()); //apache jar的ZipEntry
            zos.putNextEntry(ze);
            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));
            while ((len = bis.read(buf)) > 0) {
                zos.write(buf, 0, len);
            }
            bis.close();
            zos.closeEntry();
        }
    }

    // 預處理
    public void preProcess() throws Exception {
        HttpServletResponse response = ServletActionContext.getResponse();
        res = response.getOutputStream();
        // 清空輸出流(在迅雷下載不會出現一長竄)
        response.reset();
        // 設定輸出文件頭
        response.setHeader("Content-Disposition", "attachment;filename=document.zip");
        response.setContentType("application/zip");
        zos = new ZipOutputStream(res);
    }

    // 後處理
    public void afterProcess() throws IOException {

        zos.close();
        res.close();
    }

    public OutputStream getRes() {
        return res;
    }

    public void setRes(OutputStream res) {
        this.res = res;
    }

    public ZipOutputStream getZos() {
        return zos;
    }

    public void setZos(ZipOutputStream zos) {
        this.zos = zos;
    }

    public String[] getDownLoadPaths() {
        return downLoadPaths;
    }

    public void setDownLoadPaths(String[] downLoadPaths) {
        this.downLoadPaths = downLoadPaths;
    }

    public String getOutPath() {
        return outPath;
    }

    public void setOutPath(String outPath) {
        this.outPath = outPath;
    }

}