Java学习总结7-----Java IO

Java库的IO类分为输入与输出两个部分， 在1.0版本中提供了两个抽象基类， 所有输入的类都从InputStream继承， 所有输出的类都从OutputStream继承， 1.1提供了两个新的基类， 负责输入的Reader与输出的Writer， 但它们并不是用来替换原来老的InputStream与OutputStream， 它们主要是让Java能更好的支持国际化的需求。 原来老的IO流层只支持8位字节流， 不能很好地控制16位Unicode字符。 Java内含的char是16位的Unicode， 所以添加了Reader和Writer层次以提供对所有IO操作中的Unicode的支持。 除此之外新库也对速度进行了优化， 可比旧库更快地运行。

1.InputStream
    java.lang.Object
      java.io.InputStream

                Direct Known Subclasses:

      AudioInputStream, ByteArrayInputStream, FileInputStream, FilterInputStream, InputStream, ObjectInputStream, PipedInputStream, SequenceInputStream, StringBufferInputStream

2.OutputStream

java.lang.Object
  

java.io.OutputStream

   Direct Known Subclasses:

ByteArrayOutputStream, FileOutputStream, FilterOutputStream, ObjectOutputStream, OutputStream, PipedOutputStream

3. Reader

java.lang.Object
  

java.io.Reader

  Direct Known Subclasses:

BufferedReader, CharArrayReader, FilterReader, InputStreamReader, PipedReader, StringReader

4.Writer

  java.lang.Object

  java.io.Writer

  Direct Known Subclasses:

BufferedWriter, CharArrayWriter, FilterWriter, OutputStreamWriter, PipedWriter, PrintWriter, StringWriter

一、从控制台读取输入

//从控制台读取输入---按字符读取
public class BRRead {
  public static void main(String[] args) throws IOException {
    //throwOne();
      BufferedReader BR = new BufferedReader(new InputStreamReader(System.in));
      System.out.println("Input character:'q' to quit:");
      char c;
      do{
          c = (char)BR.read();
          System.out.println(c);
      }while(c!='q');
  }
}
//从控制台读取输入---按行读取
public class BRReadLine {
      public static void main(String[] args) throws IOException {
        //throwOne();
          BufferedReader BR = new BufferedReader(new InputStreamReader(System.in));
          String line = new String();
          System.out.println("Input lines: "+ " stop to quit:");
         // char c;
          do{
              line = BR.readLine();
              System.out.println(line);
          }while(!line.equals("stop"));
      }
    }

二、文件的读写FileInputStream、FileOutputStream

public class FileStreamDemo {

	public static void main(String[] args) throws IOException {
	
		//创建两个文件,aa.txt是已经存在文件,aa2.txt是新创建的文件
		
		File inFile = new File("d:\\aa.txt");
		
		File outFile = new File("d:\\aa2.txt");
		
		//创建流文件读入与写出类
		
		FileInputStream inStream = new FileInputStream(inFile);
		
		FileOutputStream outStream = new FileOutputStream(outFile);
		
		//通过available方法取得流的最大字符数
		
		byte[] inOutb = new byte[inStream.available()];
		
		inStream.read(inOutb);  //读入流,保存在byte数组
		
		outStream.write(inOutb);  //写出流,保存在文件newFace.gif中
		
		inStream.close();
		
		outStream.close();
	
	}

}