JAVA工具类之文件（文件流转换、存储、拷贝、清空、写入）

FileUtils.java

package com.bigbigbu.cf.common.utils;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.channels.FileChannel;
import java.util.List;

import org.apache.commons.lang3.StringUtils;

/**
* @Title: FileUtils
* @Description: 文件（文件流转换、存储、拷贝、清空、写入）
* @Company: 卜凡起的博客
* @author    FANQIBU
* @date       2018年2月2日
*/
public class FileUtils {
    // 通过get请求得到读取器响应数据的数据流
  public static InputStream getInputStreamByGet(String url) {
      try {
          HttpURLConnection conn = (HttpURLConnection) new URL(url)
                  .openConnection();
          conn.setReadTimeout(5000);
          conn.setConnectTimeout(5000);
          conn.setRequestMethod("GET");

          if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
              InputStream inputStream = conn.getInputStream();
              return inputStream;
          }

      } catch (IOException e) {
          e.printStackTrace();
      }
      return null;
  }
  //inputStream转outputStream
  public static ByteArrayOutputStream parse(InputStream in)
  {
      try {
        ByteArrayOutputStream swapStream = new ByteArrayOutputStream();
          int ch;
          while ((ch = in.read()) != -1) {   
              swapStream.write(ch);   
          }
          return swapStream;
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
      return  null;
  }
  //outputStream转inputStream
  public static ByteArrayInputStream parse(OutputStream out)
  { 
      try {
      ByteArrayOutputStream   baos=new   ByteArrayOutputStream();
      baos=(ByteArrayOutputStream) out;
      ByteArrayInputStream swapStream = new ByteArrayInputStream(baos.toByteArray());
      return swapStream;
     } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return  null;
  }
public static void main(String[] args) {
    InputStream is=getInputStreamByGet("http://mmbiz.qpic.cn/mmbiz_png/KYOtWWibVu2UiaFNlhrOrmD5OFRMXyDJMAPwwQSr5FZe7O99eoppFPxsvDEcwKBibicgKkDK7SUYT2ewUOGSheGGRg/0?wx_fmt=png");
    saveData(is,new File("d://ceshi.jpg"));
}
      // 将服务器响应的数据流存到本地文件
  public static void saveData(InputStream is, File file) {
      try (BufferedInputStream bis = new BufferedInputStream(is);
              BufferedOutputStream bos = new BufferedOutputStream(
                      new FileOutputStream(file));) {
          byte[] buffer = new byte[1024];
          int len = -1;
          while ((len = bis.read(buffer)) != -1) {
              bos.write(buffer, 0, len);
              bos.flush();
          }
      } catch (IOException e) {
          e.printStackTrace();
      }
  }

    /**
    * 
Title: copyFileUsingFileChannels
    * 
Description: 文件拷贝
    * @param source
    * @param dest
    * @throws IOException
    */
    @SuppressWarnings({ "resource" })
      public synchronized  static  void copyFileUsingFileChannels(File source, File dest) throws IOException {    
              FileChannel inputChannel = null;    
              FileChannel outputChannel = null;    
              try {
                  inputChannel = new FileInputStream(source).getChannel();
                  outputChannel = new FileOutputStream(dest).getChannel();
                  outputChannel.transferFrom(inputChannel, 0, inputChannel.size());
              } finally {
                  inputChannel.close();
                  outputChannel.close();
              }
       }
      /**
    * 
Title: clearInfoForFile
    * 
Description: 文件内容清空
    * @param fileName
    */
    public static void clearInfoForFile(String fileName) {
            if(StringUtils.isEmpty(fileName)){
                return;
            }
          File file =new File(fileName);
          try {
              if(!file.exists()) {
                  file.createNewFile();
              }
              FileWriter fileWriter =new FileWriter(file);
              fileWriter.write("");
              fileWriter.flush();
              fileWriter.close();
          } catch (IOException e) {
              e.printStackTrace();
          }
      }
    /**
    * 
Title: writeFileByLine
    * 
Description: 按行向文件写入内容
    * @throws IOException
    */
    public static void writeFileByLine(String fileName,List parameter)  {
        if(StringUtils.isEmpty(fileName) || parameter == null || parameter.size() == 0){
            return;
        }
        FileWriter fw =null;
        try {
            fw = new FileWriter(fileName);
            for (int i = 0; i < parameter.size(); i++) {
                fw.write(parameter.get(i)+"\n");
            }
        } catch (IOException e) {
              e.printStackTrace();
        }finally {
             try {
                fw.close();
            } catch (IOException e) {
            }
        }
    }

}