java 文件处理 工具类

package com.fh.util;
import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
/**
 * 说明：文件处理
 * 作者：FH Admin
 * from：fhadmin.cn
 */
public class FileUtil {
  /**获取文件大小 返回 KB 保留3位小数  没有文件时返回0
   * @param filepath 文件完整路径，包括文件名
   * @return
   */
  public static Double getFilesize(String filepath){
    File backupath = new File(filepath);
    return Double.valueOf(backupath.length())/1000.000;
  }
  /**
   * 创建目录
   * @param destDirName目标目录名
   * @return 
   */
  public static Boolean createDir(String destDirName) {
    File dir = new File(destDirName);
    if(!dir.getParentFile().exists()){        //判断有没有父路径，就是判断文件整个路径是否存在
      return dir.getParentFile().mkdirs();    //不存在就全部创建
    }
    return false;
  }
  /**
   * 删除文件
   * @param filePathAndName
   *            String 文件路径及名称 如c:/fqf.txt
   * @param fileContent
   *            String
   * @return boolean
   */
  public static void delFile(String filePathAndName) {
    try {
      String filePath = filePathAndName;
      filePath = filePath.toString();
      java.io.File myDelFile = new java.io.File(filePath);
      myDelFile.delete();
    } catch (Exception e) {
      System.out.println("删除文件操作出错");
      e.printStackTrace();
    }
  }
  /**
   * 读取到字节数组0
   * @param filePath //路径
   * @throws IOException
   */
  public static byte[] getContent(String filePath) throws IOException {
    File file = new File(filePath);
    long fileSize = file.length();
    if (fileSize > Integer.MAX_VALUE) {
      System.out.println("file too big...");
      return null;
    }
    FileInputStream fi = new FileInputStream(file);
    byte[] buffer = new byte[(int) fileSize];
    int offset = 0;
    int numRead = 0;
    while (offset < buffer.length
        && (numRead = fi.read(buffer, offset, buffer.length - offset)) >= 0) {
      offset += numRead;
    }
    // 确保所有数据均被读取
    if (offset != buffer.length) {
      throw new IOException("Could not completely read file " + file.getName());
    }
    fi.close();
    return buffer;
  }
  /**
   * 读取到字节数组1
   * 
   * @param filePath
   * @return
   * @throws IOException
   */
  public static byte[] toByteArray(String filePath) throws IOException {
    File f = new File(filePath);
    if (!f.exists()) {
      throw new FileNotFoundException(filePath);
    }
    ByteArrayOutputStream bos = new ByteArrayOutputStream((int) f.length());
    BufferedInputStream in = null;
    try {
      in = new BufferedInputStream(new FileInputStream(f));
      int buf_size = 1024;
      byte[] buffer = new byte[buf_size];
      int len = 0;
      while (-1 != (len = in.read(buffer, 0, buf_size))) {
        bos.write(buffer, 0, len);
      }
      return bos.toByteArray();
    } catch (IOException e) {
      e.printStackTrace();
      throw e;
    } finally {
      try {
        in.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
      bos.close();
    }
  }
  /**
   * 读取到字节数组2
   * 
   * @param filePath
   * @return
   * @throws IOException
   */
  public static byte[] toByteArray2(String filePath) throws IOException {
    File f = new File(filePath);
    if (!f.exists()) {
      throw new FileNotFoundException(filePath);
    }
    FileChannel channel = null;
    FileInputStream fs = null;
    try {
      fs = new FileInputStream(f);
      channel = fs.getChannel();
      ByteBuffer byteBuffer = ByteBuffer.allocate((int) channel.size());
      while ((channel.read(byteBuffer)) > 0) {
        // do nothing
        // System.out.println("reading");
      }
      return byteBuffer.array();
    } catch (IOException e) {
      e.printStackTrace();
      throw e;
    } finally {
      try {
        channel.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
      try {
        fs.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  }
  /**
   * Mapped File way MappedByteBuffer 可以在处理大文件时，提升性能
   * 
   * @param filename
   * @return
   * @throws IOException
   */
  public static byte[] toByteArray3(String filePath) throws IOException {
    FileChannel fc = null;
    RandomAccessFile rf = null;
    try {
      rf = new RandomAccessFile(filePath, "r");
      fc = rf.getChannel();
      MappedByteBuffer byteBuffer = fc.map(MapMode.READ_ONLY, 0,
          fc.size()).load();
      //System.out.println(byteBuffer.isLoaded());
      byte[] result = new byte[(int) fc.size()];
      if (byteBuffer.remaining() > 0) {
        // System.out.println("remain");
        byteBuffer.get(result, 0, byteBuffer.remaining());
      }
      return result;
    } catch (IOException e) {
      e.printStackTrace();
      throw e;
    } finally {
      try {
        rf.close();
        fc.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  }
}