spring boot定时任务接收邮件并且存储附件的方法讲解

public class TimerTaskServiceImpl implements TimerTaskService {  @Autowired  private ParseTxtServiceImpl parseTxtService;  /**   * 接收邮件    */  @Override  @Scheduled(cron="0 10 8 * * ?")  public void timerTaskInfo(){    //邮件配置信息    String host=Constants.MAIL_HOST;    String userName=Constants.MAIL_USER_NAME;    String passWord=Constants.MAIL_PASS_WORD;    //邮件配置类    Properties properties=new Properties();    //邮件配置缓存    Session session=Session.getDefaultInstance(properties);    session.setDebug(true);    String fileName=null;    try {      //邮件服务器的类型      Store store = session.getStore("pop3");      //连接邮箱服务器      store.connect(host,userName,passWord);      // 获得用户的邮件帐户      Folder folder=store.getFolder("INBOX");      if (folder == null) {        logger.info("获取邮箱文件信息为空");      }      // 设置对邮件帐户的访问权限可以读写      folder.open(Folder.READ_WRITE);      Calendar calendar=Calendar.getInstance();      calendar.add(Calendar.DATE,-1);      Date mondayDate = calendar.getTime();      SearchTerm comparisonTermLe = new SentDateTerm(ComparisonTerm.GT, mondayDate);      SearchTerm address=new SubjectTerm( "MU Report");      SearchTerm comparisonAndTerm = new AndTerm(address, comparisonTermLe);      Message[] messages = folder.search(comparisonAndTerm);      for(int i = 0 ; i < messages.length ; i++){        MimeMessage msg = (MimeMessage) messages[i];        //判断是否有附件        boolean isContainerAttachment = isContainAttachment(msg);        if (isContainerAttachment) {          //保存附件          fileName=saveAttachment(msg,Constants.STORAGE_FILE);          //保存接收到的邮件并且收件箱删除邮件         msg.setFlag(Flags.Flag.DELETED, true);        }        if(!isContainerAttachment) {          continue;        }      }      folder.close(true);      store.close();      parseTxtService.readTxt(fileName);    }catch (NoSuchProviderException e){      loggerError.error("接收邮箱信息异常:{}",e);    }catch (MessagingException e){      loggerError.error("连接邮箱服务器信息异常:{}",e);    }catch (IOException e){      loggerError.error("接收邮箱信息解析异常:{}",e);    }catch (IllegalStateException e){      loggerError.error("接收邮箱信息为空:{}",e);    }  }  /**   * 判断邮件中是否包含附件   * @return 邮件中存在附件返回true，不存在返回false   * @throws MessagingException   * @throws IOException   */  public static boolean isContainAttachment(Part part) throws MessagingException, IOException {    boolean flag = false;    if (part.isMimeType(Constants.MULTI_PART)) {      MimeMultipart multipart = (MimeMultipart) part.getContent();      int partCount = multipart.getCount();      for (int i = 0; i < partCount; i++) {        BodyPart bodyPart = multipart.getBodyPart(i);        String disp = bodyPart.getDisposition();        if (disp != null && (disp.equalsIgnoreCase(Part.ATTACHMENT) ||            disp.equalsIgnoreCase(Part.INLINE))) {          flag = true;        } else if (bodyPart.isMimeType(Constants.MULTI_PART)) {          flag = isContainAttachment(bodyPart);        } else {          String contentType = bodyPart.getContentType();          if (contentType.indexOf(Constants.APPLICATION_CONTEXT) != -1) {            flag = true;          }          if (contentType.indexOf(Constants.NAME_CONTEXT) != -1) {            flag = true;          }        }        if (flag){          break;        }      }    } else if (part.isMimeType(Constants.MESSAGE_RFC)) {      flag = isContainAttachment((Part)part.getContent());    }    return flag;  }  /**   * 保存附件   * @param part 邮件中多个组合体中的其中一个组合体   * @param destDir 附件保存目录   * @throws UnsupportedEncodingException   * @throws MessagingException   * @throws FileNotFoundException   * @throws IOException   */  public String saveAttachment(Part part, String destDir) throws UnsupportedEncodingException,      MessagingException, FileNotFoundException, IOException {    String fileName=null;    if (part.isMimeType(Constants.MULTI_PART)) {      Multipart multipart = (Multipart) part.getContent();  //复杂体邮件      //复杂体邮件包含多个邮件体      int partCount = multipart.getCount();      for (int i = 0; i < partCount; i++) {        //获得复杂体邮件中其中一个邮件体        BodyPart bodyPart = multipart.getBodyPart(i);        //某一个邮件体也有可能是由多个邮件体组成的复杂体        String disp = bodyPart.getDisposition();        if (disp != null && (disp.equalsIgnoreCase(Part.ATTACHMENT) || disp.equalsIgnoreCase            (Part.INLINE))) {          InputStream is = bodyPart.getInputStream();          saveFile(is, destDir, decodeText(bodyPart.getFileName()));          fileName=decodeText(bodyPart.getFileName());        } else if (bodyPart.isMimeType(Constants.MULTI_PART)) {          saveAttachment(bodyPart,destDir);        } else {          String contentType = bodyPart.getContentType();          if (contentType.indexOf(Constants.NAME_CONTEXT) != -1 || contentType.indexOf              (Constants.APPLICATION_CONTEXT) != -1) {            saveFile(bodyPart.getInputStream(), destDir, decodeText(bodyPart.getFileName()));            fileName=decodeText(bodyPart.getFileName());          }        }      }    } else if (part.isMimeType(Constants.MESSAGE_RFC)) {      saveAttachment((Part) part.getContent(),destDir);    }    return fileName;  }  /**   * 读取输入流中的数据保存至指定目录   * @param is 输入流   * @param fileName 文件名   * @param destDir 文件存储目录   * @throws FileNotFoundException   * @throws IOException   */  private void saveFile(InputStream is, String destDir, String fileName)      throws FileNotFoundException, IOException {    BufferedInputStream bis = new BufferedInputStream(is);    if(fileName.contains(Constants.TXT_SUFIXX)) {      BufferedOutputStream bos = new BufferedOutputStream(          new FileOutputStream(new File(destDir + fileName)));      int len = -1;      while ((len = bis.read()) != -1) {        bos.write(len);        bos.flush();      }      bos.close();      bis.close();    }  }}