자바 읽 기 파일 대전

package whut.filedeal;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;
import java.io.Reader;
public class InOutputDemo {
  public static void main(String[] args) {
    InOutputDemo demo = new InOutputDemo();
    demo.readDtaByCharBufferedReader();
  }
  //      
  public void readDataByChar() {
    try {
      File sourceFile = new File("f:\\test.txt");
      FileInputStream fin = new FileInputStream(sourceFile);
      InputStreamReader ris = new InputStreamReader(fin);
      int cc;
      while ((cc = ris.read()) > 0) {
        System.out.print((char) cc);
      }
      ris.close();
      fin.close();
    } catch (Exception e) {
      System.out.println(e);
      e.getStackTrace();
    }
  }
  //         
  public void readDataByCharArray() {
    try {
      File sourceFile = new File("f:\\test.txt");
      FileInputStream fin = new FileInputStream(sourceFile);
      InputStreamReader ris = new InputStreamReader(fin);
      char[] aa = new char[10];
      int readchar = 0;
      while ((readchar = ris.read(aa)) > 0) {
        System.out.print(new String(aa, 0, readchar));
      }
      ris.close();
      fin.close();
    } catch (Exception e) {
      System.out.println(e);
      e.getStackTrace();
    }
  }
  //  BufferedReader   
  public void readDtaByCharBufferedReader() {
    try {
      File sourceFile = new File("f:\\test.txt");
      FileInputStream fin = new FileInputStream(sourceFile);
      BufferedReader br = new BufferedReader(new InputStreamReader(fin));
      String aa;
      //   readLine   null        
      while ((aa = br.readLine()) != null) {
        System.out.println(aa);
      }
      fin.close();
      br.close();
    } catch (Exception e) {
      System.out.println(e);
      e.getStackTrace();
    }
  }
  //          ，         ，   、  、     。
  public static void readFileByBytes(String fileName) {
    File file = new File(fileName);
    InputStream in = null;
    try {
      System.out.println("            ，       ：");
      //        
      in = new FileInputStream(file);
      int tempbyte;
      while ((tempbyte = in.read()) != -1) {
        System.out.write(tempbyte);
      }
      in.close();
    } catch (IOException e) {
      e.printStackTrace();
      return;
    }
    try {
      System.out.println("            ，       ：");
      //        
      byte[] tempbytes = new byte[100];
      int byteread = 0;
      in = new FileInputStream(fileName);
      //             ，byteread         
      while ((byteread = in.read(tempbytes)) != -1) {
        System.out.write(tempbytes, 0, byteread);
      }
    } catch (Exception e1) {
      e1.printStackTrace();
    } finally {
      if (in != null) {
        try {
          in.close();
        } catch (IOException e1) {
        }
      }
    }
  }
  //          ，      ，        
  public static void readFileByChars(String fileName) {
    File file = new File(fileName);
    Reader reader = null;
    try {
      System.out.println("            ，       ：");
      //        
      reader = new InputStreamReader(new FileInputStream(file));
      int tempchar;
      while ((tempchar = reader.read()) != -1) {
        //   windows ，\r
         ，      。
        //              ，     。
        //   ，   \r，    
。  ，        。
        if (((char) tempchar) != '\r') {
          System.out.print((char) tempchar);
        }
      }
      reader.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
    try {
      System.out.println("            ，       ：");
      //        
      char[] tempchars = new char[30];
      int charread = 0;
      reader = new InputStreamReader(new FileInputStream(fileName));
      //             ，charread        
      while ((charread = reader.read(tempchars)) != -1) {
        //      \r   
        if ((charread == tempchars.length)
            && (tempchars[tempchars.length - 1] != '\r')) {
          System.out.print(tempchars);
        } else {
          for (int i = 0; i < charread; i++) {
            if (tempchars[i] == '\r') {
              continue;
            } else {
              System.out.print(tempchars[i]);
            }
          }
        }
      }
    } catch (Exception e1) {
      e1.printStackTrace();
    } finally {
      if (reader != null) {
        try {
          reader.close();
        } catch (IOException e1) {
        }
      }
    }
  }
    
  //         ，             
  public static void readFileByLines(String fileName) {
    File file = new File(fileName);
    BufferedReader reader = null;
    try {
      System.out.println("           ，      ：");
      reader = new BufferedReader(new FileReader(file));
      String tempString = null;
      int line = 1;
      //       ，    null     
      while ((tempString = reader.readLine()) != null) {
        //     
        System.out.println("line " + line + ": " + tempString);
        line++;
      }
      reader.close();
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      if (reader != null) {
        try {
          reader.close();
        } catch (IOException e1) {
        }
      }
    }
  }
  //         
  public static void readFileByRandomAccess(String fileName) {
    RandomAccessFile randomFile = null;
    try {
      System.out.println("          ：");
      //            ，     
      randomFile = new RandomAccessFile(fileName, "r");
      //     ，   
      long fileLength = randomFile.length();
      //         
      int beginIndex = (fileLength > 4) ? 4 : 0;
      //            beginIndex  。
      randomFile.seek(beginIndex);
      byte[] bytes = new byte[10];
      int byteread = 0;
      //    10   ，        10   ，       。
      //            byteread
      while ((byteread = randomFile.read(bytes)) != -1) {
        System.out.write(bytes, 0, byteread);
      }
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      if (randomFile != null) {
        try {
          randomFile.close();
        } catch (IOException e1) {
        }
      }
    }
  }
}