Java实现较大二进制文件的读、写方法

/**
 * 针对大文件存储，请依次调用beginSave、AddSave、endSave。
 * 
 * @author CK
 *
 */
public class DataUtil {

  DataOutputStream BinaryOut=null;
  BufferedWriter TextOut=null;
  String FilePath=null;
  enum SaveFileType{Text,Binary};
  SaveFileType SaveFileType;

  /**
   * double转byte[]
   * 
   * @param d
   * @return
   */
  public static byte[] double2Bytes(double d) {
    long value = Double.doubleToRawLongBits(d);
    byte[] byteRet = new byte[8];
    for (int i = 0; i < 8; i++) {
      byteRet[i] = (byte) ((value >> 8 * i) & 0xff);
    }
    return byteRet;
  }

  /**
   * byte[]转double
   * 
   * @param arr
   * @return
   */
  public static double bytes2Double(byte[] arr) {
    long value = 0;
    for (int i = 0; i < 8; i++) {
      value |= ((long) (arr[i] & 0xff)) << (8 * i);
    }
    return Double.longBitsToDouble(value);
  }
  /**
   * 大型数据存储之开始存储
   * @param FilePath 文件路径
   * @param saveFileType 保存的文件类型，文本文件、双精度所存的二进制文件
   * @return
   * @throws IOException
   */
  public boolean BeginSave(String FilePath,SaveFileType saveFileType) throws IOException {
    if (FilePath == "" || FilePath == null) {
      System.out.println("the SavePath is null.");
      return false;
    }
    this.FilePath=FilePath;
    this.SaveFileType=saveFileType;
    File dataFile = new File(FilePath);
    if (!dataFile.getParentFile().exists()) {
      dataFile.getParentFile().mkdirs();
    }
    if (dataFile.exists()) {
      dataFile.delete();
    }
    dataFile.createNewFile();
    switch(this.SaveFileType){
    case Text:
      TextOut= new BufferedWriter(new FileWriter(dataFile,true));
      break;
    case Binary:
      BinaryOut = new DataOutputStream(new FileOutputStream(dataFile,true));
      break;
    default:
      break;
      
    }    
    return true;
  }
/**
 * 大型文件存储之追加存储
 * @param DataStr 若是文本存储则无要求，若是双精度的二进制文件，以若干空格隔开
 * @return
 * @throws IOException
 */
  public boolean AddSave(String DataStr) throws IOException{
    switch(this.SaveFileType){
    case Text:
      this.TextOut.append(DataStr);
      break;
    case Binary:
      DataStr=DataStr.trim();
      String[] dataArray=DataStr.split("\\s+");
      for(int i=0;i<dataArray.length;i++){
        this.BinaryOut.write(double2Bytes(Double.parseDouble(dataArray[i])));
      }          
      break;
    default:
      break;
    
    }
    
    return true;
  }
  /**
   * 大型文件存储之结束保存，清空缓存、关闭文件。
   * @return
   * @throws IOException
   */
  public boolean EndSave() throws IOException{
    switch(this.SaveFileType){
    case Text:
      this.TextOut.flush();
      this.TextOut.close();
      break;
    case Binary:
      this.BinaryOut.flush();
      this.BinaryOut.close();
      break;
    default:
      break;    
    }
    
    return true;
  }
 /**
   * 将字符串保存为文本文件（一次完成）
   * 
   * @param DataStr
   *      文件内容
   * @param SavePath
   *      文件路径，包含文件名、后缀
   * @return
   * @throws IOException
   */
  public boolean saveTextFile(String DataStr, String SavePath)
      throws IOException {
    if (DataStr == "" || DataStr == null) {
      System.out.println("the dataStr is null.");
      return false;
    }
    if (SavePath == "" || SavePath == null) {
      System.out.println("the SavePath is null.");
      return false;
    }
    File dataFile = new File(SavePath);
    if (!dataFile.getParentFile().exists()) {
      dataFile.getParentFile().mkdirs();
    }
    if (dataFile.exists()) {
      dataFile.delete();
    }
    dataFile.createNewFile();
    BufferedWriter out;

    out = new BufferedWriter(new FileWriter(dataFile));

    out.append(DataStr);
    out.flush();
    out.close();

    return true;
  }

  /**
   * 双精度存为二进制数据（一次存储）
   * 
   * @param DataStr 双精度数据组成的字符串，以若干空格隔开
   * @param OutputPath
   * @return
   * @throws IOException
   */
  public boolean saveBinaryFile(String DataStr, String OutputPath) throws IOException {

    if (DataStr == "" || DataStr == null) {
      System.out.println("the dataStr is null.");
      return false;
    }
    if (OutputPath == "" || OutputPath == null) {
      System.out.println("the OutputPath is null.");
      return false;
    }
    File dataFile = new File(OutputPath);

    if (!dataFile.getParentFile().exists()) {
      dataFile.getParentFile().mkdirs();
    }
    if (dataFile.exists()) {
      dataFile.delete();
    }
    dataFile.createNewFile();
    DataOutputStream out;
    out = new DataOutputStream(new FileOutputStream(dataFile));
    // 数据处理
    DataStr=DataStr.trim();
    String[] dataArray=DataStr.split("\\s+");
    for(int i=0;i<dataArray.length;i++){
      out.write(double2Bytes(Double.parseDouble(dataArray[i])));
    }    
    out.flush();
    out.close();
    return true;

  }
}

/**
 * 测试二进制大文件读写（200M左右）
 * @author ck
 *
 */
public class FileTest {
  static String inputFilePath=""; //输入文件路径，包含文件名后缀
  static String outputFilePath=""; //输出文件名，包含文件名后缀
  
  public static void file2file() throws IOException{
    DataUtil dataUtil=new DataUtil(); 
     DataInputStream br=new DataInputStream( 
         new BufferedInputStream( 
         new FileInputStream(inputFilePath))); 
        dataUtil.BeginSave(outputFilePath, SaveFileType.Text); //初始化，创建文件，采用文件追加存储的思路
         byte[] oneData=new byte[8];
         int i=0,count =0 ;
        while(br.read(oneData, 0, 8)!=-1){  
          i=i+1;
          dataUtil.AddSave(String.valueOf(DataUtil.bytes2Double(oneData)));          
          if(i/23543==0){
            count++;
            System.out.println(count+"\n");

          }
        }
        dataUtil.EndSave();    //将还在缓存中的数据写入到文件中，关闭文件。 
  }
}