Java面向对象编程3.1.pptVIP

Topics Covered Today 3.1?Input and Output Programming 3.1.0 Java I/O Stream 3.1.1?File I/O 3.1.2?Using File I/O in the Library System What is an I/O Stream? An I/O Stream represents an input source or an output destination A stream can represent many different kinds of sources and destinations disk files, devices, other programs, a network socket, and memory arrays Streams support many different kinds of data simple bytes, primitive data types, and objects I/O Streams No matter how they work internally, all streams present the same simple model to programs that use them A stream is a sequence of data Input Stream A program uses an input stream to read data from a source (a file, memory, a socket), and reads the information sequentially, one item at a time. Output Stream A program uses an output stream to write data to a destination, and writing the information out sequentially, one item at time. Types of Streams General Stream Types Character and Byte Streams Character vs. Byte Input and Output Streams Based on source or destination Node and Filter Streams Whether the data on a stream is manipulated or transformed or not Abstract Classes InputStream OutputStream Reader Writer InputStream Abstract Class Read data from InputStream： int read( ); Reads the next byte of data from the input stream int read( byte b[ ] ); Reads some number of bytes from the input stream and stores them into the buffer array b. int read( byte b[ ], int off, int len ); Reads up to len bytes of data from the input stream into an array of bytes. int available( ); ?Returns the number of bytes that can be read Close Stream： close( ); Closes this input stream and releases any system resources associated with the stream. OutputStream Abstract Class Write data: void write( int b ); Writes the specified byte to this output stream. void write( byte b[ ] ); Writes b.length bytes from the specified byte array to this output stream void write( byte b[ ], int off, int len ); Writes len bytes from th