周报：8.15-8.21，Struts2实现文件上传和下载（上传）

本文链接：https://blog.youkuaiyun.com/juice_panda/article/details/52292815

网站编写很多时候要实现附件上传和下载。
而我这里说下自己用ajax技术写文件上传和下载的过程和方法。
先不急着说实现的方法，在写之前先确定几件事：
1.文件存哪
2.哪些功能要用到上传和下载。（这点很重要，如我做的指标项管理是要在上传的时候可以添加文件，添加文件的过程是，在文件控件选择文件点击上传，这时候文件应该上传到临时文件夹里，而数据库应该有个表记录上传的文件，具体的字段有，主键文件id，文件路径，文件原名称，文件转化后唯一名称等。而上传成功后返回前台该文件的id，若要显示文件名，也可多传一个文件原名称）。
确定后实现上传，具体流程：
1.页面上定义一个file控件和上传操作按钮，也可以定义一些文本框查看返回数据。

具体代码：

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ page contentType="text/html; charset=utf-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!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">
<html>
  <head> <title>文件上传测试</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <script type="text/javascript" src='<c:url value="/resource/js/data.js" />'></script>
    <script src="${pageContext.request.contextPath}/resource/m/boot.js" type="text/javascript"></script>
    <script type="text/javascript" src="${pageContext.request.contextPath}/resource/m/miniui/jquery-1.7.2.min.js"/></script>
    <script type="text/javascript" src="${pageContext.request.contextPath}/resource/js/ajaxfileupload.js"></script>
    <LINK href="<c:url value='/resource/css/custom.css'/>" type="text/css" rel="stylesheet">

  </head>

  <body>
  <div id="tabUnploadForm">
  <fieldSet>
  <legend style="font-size:18px">上传测试</legend>
  <table>
     <tr>
     <td>
     <input  type="file" id="uploadfile"  name="file" />
     </td>
     </tr>
     <tr>
    <td ><input id="upload3"  type="button" value="上传测试"onclick="return uploadFile3();"/></td>
   </tr>
   <tr>
   <td>
   文件id：
   </td>
   <td>
   <input id ="tmpfileid"  class = "mini-textbox "  name="tmpfileid"/>
   </td>
   <td>
   文件路径：
   </td>
   <td>
   <input id ="uploaddir"  class = "mini-textbox "  name="uploaddir"/>
   </td>
   <td>
   文件名：
   </td>
   <td>
   <input id ="filename"  class = "mini-textbox "  name="filename"/>
   <input id ="savename"  class= "mini-textbox"  name="savename"/>

   </td>
   <td width="10%"><a href="/hzrsmh/portal/common/download.action?fileType=00&fileid=106"/>下载</td>
   </tr>

  </table>
  </fieldSet>
  </div>
  <script type="text/javascript">
    function uploadFile3(){
                    $.ajaxFileUpload({
                        url:'<c:url value="/portal/common/uploadFile.action"/>',
                        secureuri:false,
                        fileElementId : 'uploadfile',
                        dataType : 'json',
                        success:function(data,status){
                        alert("上传成功");  
                        var tf = mini.get("tmpfileid");
                        var ul = mini.get("uploaddir");
                        var fn = mini.get("filename");
                        var sn = mini.get("savename");
                        tf.setValue(data.result[0].tmpfileid);
                        ul.setValue(data.result[0].uploaddir);
                        fn.setValue(decodeURI(data.result[0].filename)); 
                        sn.setValue(data.result[0].savename);
                          },
                         error:function(data,status,e){
                         alert(e);
                         alert(data.msg);
                          }
                     });
    }
  </script>

  </body>
</html>

注：上传要导入ajaxfileupload.js，界面使用miniui，要导入jquery-1.7.2.min.js
2.在action中获得返回的文件，文件名和编码类型，具体action继承于BaseUploadAction，它的作用是打包一些数据传输的方法，节省代码。
BaseUploadAction(未给出import):



public abstract class BaseUploadFileAction extends ActionSupport implements AjaxProvider, ModelDriven, SessionAware,
ParameterAware, ServletRequestAware, ServletResponseAware{
    private Writer writer;

    private String defaultEncoding;

    public static final String ERRORS = "{success:false,result:[{}],exception:[{msg:'%s'}]}";

    protected Map session;
    protected Map parameters;
    protected HttpServletRequest servletRequest;
    protected HttpServletResponse servletResponse;

    private String responseData;
    private String errorResultLocation;
    private boolean ajaxSuccess;

    public BaseUploadFileAction() {

        this.defaultEncoding = "UTF-8";
    }

    @Override
    public String execute() throws Exception {

        String result = null;

        try {
            result = operate();
        }
        catch (Exception e) {
            writerJson(String.format(ERRORS, getErrorMsg(e)));
            e.printStackTrace();
            return null;
        }

        writerJson(result);

        return null;
    }

    public String getErrorMsg(Throwable throwable) {

        if (throwable instanceof BusinessException) {
            return throwable.getMessage();
        }

        return getErrorMsg(throwable.getCause());
    }

    public void writerJson(String json) throws IOException {

        if(json ==null ||json.trim().length()==0)
            return;

        HttpServletResponse response = ServletActionContext.getResponse();

        String contentType = "text/html" + ";charset=" + defaultEncoding;

        response.setContentType(contentType);

        response.getWriter().write(json);
        response.getWriter().flush();
    }

    public Object getModel() {
        return getValueObject();
    }

    public Map getSession() {
        return this.session;
    }

    public void setSession(Map session) {
        this.session = session;
    }

    public Map getParameters() {
        return this.parameters;
    }

    public void setParameters(Map parameters) {
        this.parameters = parameters;
    }

    public HttpServletRequest getServletRequest() {
        return this.servletRequest;
    }

    public HttpServletResponse getServletResponse() {
        return this.servletResponse;
    }

    public void setServletRequest(HttpServletRequest servletRequest) {
        this.servletRequest = servletRequest;
    }

    public void setServletResponse(HttpServletResponse servletResponse) {
        this.servletResponse = servletResponse;
    }


    public String getErrorResultLocation() {

        return this.errorResultLocation;
    }


    public String getResponseData() {

        return this.responseData;
    }


    public boolean hasAjaxErrors() {

        String object = (String)ActionContext.getContext().get("com.framework.core.web.ajax.errors.flag");
        return Boolean.parseBoolean(object);
    }


    public boolean isAjaxSuccess() {

        return this.ajaxSuccess;
    }


    public void setAjaxSuccess(boolean ajaxSuccess) {
        this.ajaxSuccess = ajaxSuccess;
    }


    public void setErrorResultLocation(String errorResultLocation) {
        this.errorResultLocation = errorResultLocation;
    }


    public void setResponseData(String arg0) {
        this.responseData = responseData;
    }

    protected abstract String operate();

    protected abstract ValueObject getValueObject();

}

ajaxFIleUpload（import没给出）:


public class AjaxFileUploadAction extends BaseUploadFileAction{

    private File file;

    private String fileFileName;  

    private String fileContentType;

    WpsTmpFileService wpsTmpFileService ;


    public void setWpsTmpFileService(WpsTmpFileService wpsTmpFileService){
        this.wpsTmpFileService = wpsTmpFileService;
    }

    @Override
    protected ValueObject getValueObject() {
        // TODO Auto-generated method stub
        return null;
    }


    @Override
    protected String operate() {
        // TODO Auto-generated method stub
        String json = null;
        String username = UserContextUtils.getOperatorName();
        Long userid = UserContextUtils.getOperatorId();
        String path = servletRequest.getRealPath("")+"/upload/temp/";
        try{
        WpsTmpFileVO tmpFileVO = new WpsTmpFileVO();
        WpsTmpFileDTO tmpFileDTO= wpsTmpFileService.uploadFileToTmp(file, path, fileFileName, username, userid);
        tmpFileVO.setFileName(tmpFileDTO.getFilename());
        tmpFileVO.setTmpFileId(tmpFileDTO.getTmpfileid());
        tmpFileVO.setUploadDir(tmpFileDTO.getUploaddir());
        tmpFileVO.setSavename(tmpFileDTO.getSavename());
        //生成json操作
        json = String.format("{success:true,result:[{tmpfileid:'%s',uploaddir:'%s',filename:'%s',savename:'%s'}]}",tmpFileVO.getTmpFileId(),tmpFileVO.getUploadDir(),tmpFileVO.getFileName(),tmpFileVO.getSavename());
        this.servletResponse.setContentType("text/plain;charset=utf-8");
        this.servletResponse.getWriter().write(json);
        this.servletResponse.getWriter().flush();   
        }catch(IOException e){
         e.printStackTrace();   
        }
        return null;
    }


    public File getFile() {
        return file;
    }

    public void setFile(File file) {
        this.file = file;
    }

    public String getFileFileName() {
        return fileFileName;
    }

    public void setFileFileName(String fileFileName) {
        this.fileFileName = fileFileName;
    }

    public String getFileContentType() {
        return fileContentType;
    }

    public void setFileContentType(String fileContentType) {
        this.fileContentType = fileContentType;
    }

}

3.在service层中先进行文件上传操作，再将文件信息保存到表中并返回sequence生成的文件id。


public class WpsTmpFileServiceImpl implements WpsTmpFileService{

    private static final String DEFAULT_VALUE="00";

    WpsTmpFileDao wpsTmpFileDao ;

    public void setWpsTmpFileDao(WpsTmpFileDao wpsTmpFileDao){
        this.wpsTmpFileDao = wpsTmpFileDao;
    }

    //上传文件操作，上传到upload/temp/
    public WpsTmpFileDTO uploadFileToTmp(File file ,String path,String filename,String username,Long userid){
        String fileName = getRandomName(filename);
        String filepath = path+fileName;
        String url = filepath;
        url = url.replaceAll("\\\\", "/");
        File saveFile = new File(new File(path),"新文件名.jpg");
        if(!saveFile.getParentFile().exists()){
            saveFile.getParentFile().mkdirs();
        }
        try 
        {
            InputStream in = new FileInputStream(file);//把文件读入
            OutputStream out = new FileOutputStream(url);//建立一个上传文件的输出流

            int bytesRead;
            byte[] buffer = new byte[1024];
            while ((bytesRead = in.read(buffer, 0, 1024)) != -1) {
                out.write(buffer, 0, bytesRead);//将文件写入服务器
            }
            out.close();
            in.close();
        } 
        catch (Exception e) 
        {
            e.printStackTrace();
        }
        filepath="/upload/temp/";
        return SaveToTable(filepath,fileName,username,userid,filename);


    }
    //将文件数据保存到临时文件表
    public WpsTmpFileDTO SaveToTable(String filepath , String filename ,String username,Long userid,String savename){
        WpsTmpFileDTO tmpFileDTO = new WpsTmpFileDTO();
        Date now = new Date();
        tmpFileDTO.setFilename(filename);
        tmpFileDTO.setType(DEFAULT_VALUE);
        tmpFileDTO.setUploaddir(filepath);
        tmpFileDTO.setUsername(username);
        tmpFileDTO.setUserid(userid);
        tmpFileDTO.setUploadtime(now);
        tmpFileDTO.setSavename(savename);
        WpsTmpFile tmpFile = ModelUtils.copyAs(tmpFileDTO, WpsTmpFile.class);
        return wpsTmpFileDao.SaveAndGet(tmpFile);   
    }
//获取文件类型
public static String getPostfix(String path){
        if(path ==null || "".equals(path.trim())){
            return "";
        }
        if(path.contains(".")){
            return path.substring(path.lastIndexOf(".")+1,path.length());
        }
        return "";
    }   

//生成文件随机名
    public static String getRandomName(String filename){

        SimpleDateFormat dateFormat=new SimpleDateFormat("yyyyMMddHHmmss");
        String dateStr=dateFormat.format(new Date());
        Random r = new Random();
        Integer integer = new Integer(r.nextInt(10000));
        String s =String.valueOf(integer);

        filename = dateStr+s+"."+getPostfix(filename);

        return filename;

    }
    public WpsTmpFileDTO getFileById(String fileid){
        Long lfileid = Long.parseLong(fileid);
        return ModelUtils.copyAs(wpsTmpFileDao.load(lfileid), WpsTmpFileDTO.class);
    }

@Override
public WpsTmpFile getTmpFileById(long tmpfileid) {
    return wpsTmpFileDao.getTmpFileById(tmpfileid);
}

}