java I/O流

输入流(读取数据的流)

BufferedInputStream---继承--->FileInputStream--继承--->InputStream------>

(1)字节流操作中文数据不是特别的方便，所以就出现了转换流。
            转换流的作用就是把字节流转换字符流来使用。
(2)转换流其实是一个字符流
                  字符流 = 字节流 + 编码表

 

a. 字节输入流

InputStram

read();

read(byte b[]);

read(byte b[], int off, int len);

skip(long n);

available();

close();

InputStream fis=new FileInputStream("D:\\1.txt");
int by=0;
while((by=fis.read())!=-1)
{
System.out.print((char)by);
}
fis.close();

FileInputStream:  继承InputStream

方法:

FileInputStream(String name);

FileInputStream(File file);

FileInputStream(FileDescriptor fdObj);

open(String name);

read();

read(byte b[]);

read(byte b[], int off, int len);

skip(long n);

available();

close();

FileInputStream fis=new FileInputStream("D:\\1.txt");
int by=0;
while((by=fis.read())!=-1)
{
System.out.print((char)by);
}
fis.close();

b. 字符输入流

Writer

abstract class Writer implements Appendable, Closeable, Flushable

应使用它们的子类来创建实体对象

子类:

CharArrayReader	从字符数组读取的输入流
BufferedReader	缓冲输入字符流
PipedReader	输入管道
InputStreamReader	将字节转换到字符的输入流
FilterReader	过滤输入流
StringReader	从字符串读取的输入流
LineNumberReader	为输入数据附加行号
PushbackReader	返回一个字符并把此字节放回输入流
FileReader	从文件读取的输入流

          FileReader----继承---->InputStreamReader

FileReader fd=new FileReader("D:\\1.txt");
int i=0;
while((i=fd.read())!=-1)
{
      System.out.print((char)i);
}

c. 缓冲区输入流

BufferedReader

InputStream fis=new FileInputStream("D:\\1.txt");
BufferedReader w=new BufferedReader(new InputStreamReader(fis));
String s=null;
while((s=w.readLine())!=null)
{
    System.out.println(s);
}

BufferedInputStream   继承FilterInputStream

InputStream fis=new FileInputStream("D:\\1.txt");
BufferedInputStream bis=new BufferedInputStream(fis);

int s=0;
while((s=bis.read())!=-1)
{
System.out.print((char)s);
}

d.内存输入流(特殊流)   需要先写再读

ByteArrayInputStream

ByteArrayOutputStream baos = new ByteArrayOutputStream();

// 写数据
for (int x = 0; x < 10; x++) {
baos.write(("hello" + x).getBytes());
}

ByteArrayInputStream bais=new ByteArrayInputStream(baos.toByteArray());

int s=0;
while((s=bais.read())!=-1)
{
System.out.print((char)s);
}

CharArrayStream

CharArrayWriter baos = new CharArrayWriter();
String str="asdfgasgretfgertgergasdrg";
// 写数据
for (int x = 0; x < 2; x++)
{
baos.write(str.toCharArray());
}

CharArrayReader bais=new CharArrayReader(baos.toCharArray());

int s=0;
while((s=bais.read())!=-1)
{
System.out.print((char)s);
}

StringReader

StringWriter baos = new StringWriter();
String str="asdfgasgretfgertgergasdrg";
// 写数据
for (int x = 0; x < 2; x++)
{
baos.write(str);
}
StringReader bais=new StringReader(baos.toString());
int s=0;
while((s=bais.read())!=-1)
{
System.out.print((char)s);
}

e. 数据输入流

DataInputStream

// 创建数据输入流对象
DataInputStream dis = new DataInputStream(new FileInputStream("dos.txt"));
// 读数据
byte b = dis.readByte();
short s = dis.readShort();
int i = dis.readInt();
long l = dis.readLong();
float f = dis.readFloat();
double d = dis.readDouble();
char c = dis.readChar();
boolean bb = dis.readBoolean();
// 释放资源
dis.close();
System.out.println(b);
System.out.println(s);
System.out.println(i);
System.out.println(l);
System.out.println(f);
System.out.println(d);
System.out.println(c);
System.out.println(bb);

f.转换输入流(字节转字符)

InputStreamReader

InputStream is = new FileInputStream("D:\\1.txt");
InputStreamReader isr = new InputStreamReader(is, "GBK");
int i = 0;
while ((i=isr.read())!=-1)
{
System.out.print((char)i);
}

g. 打印输入流(只能写不能读)