io流输入输出流.ppt

.io包是一组流类。IO流根据读写单位的不同分为两种:字节流:抽象父类是InputStream和OutputStream字符流:抽象父类是Reader和WriterInputStream5-1InputStream类是抽象类,因此不能创建此类的对象。子类包括FileInputStreamFilterInputStreamByteArrayInputStreamStringBufferInputStream……InputStream5-2InputStream类的体系结构InputStreamSequenceInputStreamByteArrayInputStreamPipedInputStreamFileInputStreamPushbackInputStreamLineNumberInputStreamBufferedInputStreamDataInputStreamStringBufferInputStreamFilterInputStreamInputStream5-3常用方法intread()读取下一个字节intread(byte[]b)read(b,0,)intread(byte[]b,intoffset,intlen)返回实际读取的字节数longskip(longn)跳过n个字节InputStream5-4FileInputStream类从实际磁盘文件读取数据FileInputStreamf=newFileInputStream(“");Filef=newFile(“"); FileInputStreamf=newFileInputStream(f);FileDescriptorfd=newFileDescriptor(); FileInputStreamf=newFileInputStream(fd);InputStream5-5ByteArrayInputStream类在字节数组中执行读写操作定义两种构造函数ByteArrayInputStreamb=newByteArrayInputStream(buf);ByteArrayInputStreamb=newByteArrayInputStream(buf,off,len);StringBufferInputStream类类似于ByteArrayInputStream,将字符串用作内部缓冲器StringBufferInputStreamsbif=newStringBufferInputStream(s);OutputStream5-1OutputStream为抽象类定义用于写入字节或字节数组的方法OutputStream5-2OutputStream类的体系结构OutputStreamFileOutputStreamByteArrayOutputStreamPipedOutputStreamDataOutputStreamFilterOutputStreamBufferedOutputStreamPrintStream