- DataInputStream을 사용하여 키보드에서 메모리로 데이터를 읽고 문자 1개를 메모리로 읽는 데 1초가 걸리며 이 문자는 FileOutputStream에 의해 파일에 1초 더 소비되어 기록된다고 가정해 보겠습니다.
- So for reading and writing a file will take 200 sec. This is wasting a lot of time. 반면에 Buffered 클래스가 사용되는 경우 파일에 즉시 쓸 수 있는 버퍼의 문자로 먼저 채워지는 버퍼를 제공합니다. Buffered classes should be used in connection to other stream classes.
- First the DataInputStream reads data from the keyboard by spending 1 sec for each character. This character is written into the buffer. Thus to read 100 characters into a buffer it will take 100 second time. Now FileOutputStream will write the entire buffer in a single step. So reading and writing 100 characters took 101 sec only. In the same way reading classes are used for improving the speed of reading operation. Attaching FileOutputStream to BufferedOutputStream as:
BufferedOutputStream bout=new BufferedOutputStream(fout1024);
Here the buffer size is declared as 1024 bytes. If the buffer size is not specified then a default size of 512 bytes is used - Java의 파일 클래스
- FileWriter 및 FileReader를 사용하여 Java에서 파일 처리
DataInputStream dis =new DataInputStream(System.in);Here System.in represent the keyboard which is linked with DataInputStream object
FileOutputStream fout=new FileOutputStream(file.txt);
ch=(char)dis.read(); fout.write(ch);
//Java program to demonstrate creating a text file using FileOutputStream import java.io.BufferedOutputStream; import java.io.DataInputStream; import java.io.FileOutputStream; import java.io.IOException; class Create_File { public static void main(String[] args) throws IOException { //attach keyboard to DataInputStream DataInputStream dis=new DataInputStream(System.in); // attach file to FileOutputStream FileOutputStream fout=new FileOutputStream('file.txt'); //attach FileOutputStream to BufferedOutputStream BufferedOutputStream bout=new BufferedOutputStream(fout1024); System.out.println('Enter text (@ at the end):'); char ch; //read characters from dis into ch. Then write them into bout. //repeat this as long as the read character is not @ while((ch=(char)dis.read())!='@') { bout.write(ch); } //close the file bout.close(); } }
If the Program is executed again the old data of file.txt will be lost and any recent data is only stored in the file. If we don’t want to lose the previous data of the file and just append the new data to the end of already existing data and this can be done by writing true along with file name. FileOutputStream fout=new FileOutputStream(file.txttrue);
BufferedOutputStream을 사용하여 효율성 향상
Normally whenever we write data to a file using FileOutputStream as:fout.write(ch);Here the FileOutputStream is invoked to write the characters into the file. Let us estimate the time it takes to read 100 characters from the keyboard and write all of them into a file.
C:> javac Create_File.java C:> java Create_File Enter text (@ at the end): This is a program to create a file @ C:/> type file.txt This is a program to create a file