file-online-preview/jodconverter-web/src/main/java/cn/keking/utils/DownloadUtils.java

package cn.keking.utils;

import cn.keking.config.ConfigConstants;
import cn.keking.hutool.URLUtil;
import cn.keking.model.FileAttribute;
import cn.keking.model.ReturnResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import java.io.*;
import java.net.*;
import java.util.UUID;

/**
 * @author yudian-it
 */
@Component
public class DownloadUtils {

    private static final Logger LOGGER = LoggerFactory.getLogger(DownloadUtils.class);

    private String fileDir = ConfigConstants.getFileDir();

    @Autowired
    private FileUtils fileUtils;

    private static final String URL_PARAM_FTP_USERNAME = "ftp.username";
    private static final String URL_PARAM_FTP_PASSWORD = "ftp.password";
    private static final String URL_PARAM_FTP_CONTROL_ENCODING = "ftp.control.encoding";

    /**
     * @param fileAttribute
     * @return
     */
    public ReturnResponse<String> downLoad(FileAttribute fileAttribute, String  fileName) {
        String urlAddress = fileAttribute.getDecodedUrl();
        String type = fileAttribute.getSuffix();
        ReturnResponse<String> response = new ReturnResponse<>(0, "下载成功!!!", "");
        URL url = null;
        try {
            urlAddress = URLUtil.normalize(urlAddress, true);
            url = new URL(urlAddress);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
        UUID uuid = UUID.randomUUID();
        if (null == fileName) {
            fileName = uuid+ "."+type;
        } else { // 文件后缀不一致时，以type为准(针对simText【将类txt文件转为txt】)
            fileName = fileName.replace(fileName.substring(fileName.lastIndexOf(".") + 1), type);
        }
        String realPath = fileDir + fileName;
        File dirFile = new File(fileDir);
        if (!dirFile.exists()) {
            dirFile.mkdirs();
        }
        try {
            if ("ftp".equals(url.getProtocol())) {
                String ftpUsername = fileUtils.getUrlParameterReg(fileAttribute.getUrl(), URL_PARAM_FTP_USERNAME);
                String ftpPassword = fileUtils.getUrlParameterReg(fileAttribute.getUrl(), URL_PARAM_FTP_PASSWORD);
                String ftpControlEncoding = fileUtils.getUrlParameterReg(fileAttribute.getUrl(), URL_PARAM_FTP_CONTROL_ENCODING);
                FtpUtils.download(fileAttribute.getUrl(), realPath, ftpUsername, ftpPassword, ftpControlEncoding);
            } else {
                URLConnection connection = url.openConnection();
                InputStream in = connection.getInputStream();

                FileOutputStream os = new FileOutputStream(realPath);
                byte[] buffer = new byte[4 * 1024];
                int read;
                while ((read = in.read(buffer)) > 0) {
                    os.write(buffer, 0, read);
                }
                os.close();
                in.close();
            }
            response.setContent(realPath);
            // 同样针对类txt文件，如果成功msg包含的是转换后的文件名
            response.setMsg(fileName);

             // txt转换文件编码为utf8
            if("txt".equals(type)){
                convertTextPlainFileCharsetToUtf8(realPath);
            }
            return response;
        } catch (IOException e) {
            LOGGER.error("文件下载失败", e);
            response.setCode(1);
            response.setContent(null);
            if (e instanceof FileNotFoundException) {
                response.setMsg("文件不存在!!!");
            } else {
                response.setMsg(e.getMessage());
            }
            return response;
        }
    }

  /**
   * 转换文本文件编码为utf8
   * 探测源文件编码,探测到编码切不为utf8则进行转码
   * @param filePath 文件路径
   */
  private static void convertTextPlainFileCharsetToUtf8(String filePath) throws IOException {
    File sourceFile = new File(filePath);
    if(sourceFile.exists() && sourceFile.isFile() && sourceFile.canRead()) {
      String encoding = null;
      try {
        FileCharsetDetector.Observer observer = FileCharsetDetector.guessFileEncoding(sourceFile);
        // 为准确探测到编码,不适用猜测的编码
        encoding = observer.isFound()?observer.getEncoding():null;
        // 为准确探测到编码,可以考虑使用GBK  大部分文件都是windows系统产生的
      } catch (IOException e) {
        // 编码探测失败,
        e.printStackTrace();
      }
      if(encoding != null && !"UTF-8".equals(encoding)){
        // 不为utf8,进行转码
        File tmpUtf8File = new File(filePath+".utf8");
        Writer writer = new OutputStreamWriter(new FileOutputStream(tmpUtf8File),"UTF-8");
        Reader reader = new BufferedReader(new InputStreamReader(new FileInputStream(sourceFile),encoding));
        char[] buf = new char[1024];
        int read;
        while ((read = reader.read(buf)) > 0){
          writer.write(buf, 0, read);
        }
        reader.close();
        writer.close();
        // 删除源文件
        sourceFile.delete();
        // 重命名
        tmpUtf8File.renameTo(sourceFile);
      }
    }
  }
}