1, stream: It is an abstraction of the process of transmitting data from the producer (such as keyboard, disk file, memory, or other device) through a buffer mechanism to accept the process of accepting the data (such as screen, file or memory, etc.). 2. The relevant Java package: java.io package includes many classes to provide many aspects of the relevant documents. 3. Categories of file name and directory name: File class is independent of the system platform, using the constructor file (String Path), File (String Path, String Name), File (File Dir, String Name), etc. Create a File object; Use canread (), canwrite (), getParent (), getPath () and other member functions to implement the operation of each attribute to the file. Import java.io. *; public class filetest {public static void main (string "args) {string filename =" c: //temp//myfile.dat "file myfile = new file (filename); if (! myfile ()) {System.err.Println ("can't find" filename); return;} system.out.println ("file" filename "is" myfile.length () "bytes long ! "); If (myfile. Isdirectory ()) {system.err.println (" file " filename " is a directory! "); Return;}}} 4, related to file content (data) operation class: 4.1 Input Output Abstract Foundation INPUTSTREAM / OUTPUTSTREAM, implementing the basic function of file content operation Read (), Write (), close (), Skip (), etc .; generally create its derived class object (complete specified special features) ) To implement file reading and writing. Technologies should be paid to abnormal processing in the programming process of document reading and writing. 4.2 FileInputStream / FileOutputStream: Used for local file reading and writing (binary format reading and writing and is sequential reading and writing, reading and writing to create different file stream objects); the basic process of reading and writing programming of local files is: 1 Generate file stream Object (I should be a FileInputStream class when reading the file, and the file write should be the fileoutputstream class); 2 Call the function function in the fileInputstream or FileOutputStream class, such as read (), write (int b), etc.) read and write file content; 3 Close File (Close ()). 4.3 PipedInputStream / PipedputStream: Used for pipe input and output (directly connected to another program or a thread input port directly to another program or a thread.
Need to connect when operating); 4.3.1 Pipeline connection: One of the methods is to direct the output of a program as another program input by constructive function, indicating the target pipe object pipedinputStream PINPUT = New PipedInputStream (); PipedOutputStream pOutput = new PipedOutputStream (pInput); the second method is to use any of the two sides of a class member function connect () connected PipedInputStream pInput = new PipedInputStream (); PipedOutputStream pOutput = new PipedOutputStream (); pinput.connect (pOutput); 4.3.2 Input and Output of Pipes: Output Pipe Object Call WRITE () member function output data (i.e., send data to the input of the pipe); and the input pipe object calls the read () member function to read data (ie from output pipeline Get data. This is mainly implemented by means of a buffer mechanism provided by the system. 4.4, random file read / write: RandomaccessFile class (it directly inherits the Object class and non-inputStream class), so that data in any location in the read / write file (pointer only needs to change the read and write position of the file). The basic procedure for the read and write programming of the random file is: 1 generate flow objects and indicate the type of read and write; 2 Move read and write position; 3 read and write file content; 4 Close the file. Stringbuffer buf = new stringbuffer (); char ch; while ((CH = (char) system.in.read ())! = '/ N') {buf.append (ch);} // read and write mode can be "r" or "rw" randomaccessfile myfilestream = new randomaccessfile ("myfile.dat", "rw"); myfilestream.length ()); myfilestream.writebytes (buf.tostring ()); // Put the user Add from the keyboard input to the end myFileStream.close (); 4.5 DataInput / DataOutput interface: implementation with the machine-independent of the various data formats read and write (such as readchar (), readint (), readlong (), readfloat () And readline will return a string). The RandomaccessFile class implements the interface, which has a more flexible data read and write than the FileInputStream or FileoutPutStream class. 4.6 Standard input and output flow: system.in (such as: char c = system.in.read ()) and system.out (such as: system.out.println (), system.out.println ()).
