Io stream operations

I. Io stream

1. Io streams are used to process data transmission between devices. Java streams are used to transmit data.

2. Basic operation rules

1> specify the source and purpose.

2> whether the operated data is plain text.

3> when the system is clear, it is clear which specific object to use.

Ii. Io stream Structure

Io stream

| --- Byte stream

| -- Input stream abstract base class: inputstream

| -- Output stream abstract base class: outputtream

| --- Batch stream

| -- Input stream abstract base class: Reader

| -- Abstract base class of the output stream: writer

Note: The subclass names derived from these four classes are suffixed with their parent class names.

For example, filereader, a subclass of Reader

Filewriter, a subclass of writer

Filereader program example:

Package Tan; import Java. io. filereader; public class filereaderdemo {public static void main (string [] ARGs) {filereader Fr = NULL; try {Fr = new filereader ("demo.txt "); // define an array of characters. Used to store read characters. // The read (char []) returns the number of characters read. Char buff [] = new char [100]; int num = 0; while (num = Fr. Read (buff ))! =-1) {system. out. println (new string (buff, 0, num) ;}} catch (exception e) {// todo: handle exception} finally {try {Fr. close () ;}catch (exception E2) {// todo: handle exception }}}}

TIPS:

// Pass a true parameter, indicating that the existing file is not overwritten. Data is continued at the end of an existing file. FW = new filewriter ("demo.txt", true); FW. Write ("Tan Zheng Qiang ");

Program Example 1: byte stream File Replication: the output is made every read in a loop until the end of the file.

Package Tan; // 1. import Io package import Java. io. *; public class test {public static void main (string [] ARGs) {fileinputstream FD = NULL; fileoutputstream Fos = NULL; try {// 2. generate the object that represents the input stream. The object is the new fileinputstream ("C:/users/Administrator/workspace/IO stream operation/from.txt"); Fos = new fileoutputstream ("C: /users/Administrator/workspace/IO stream operation/to.txt "); // 3. generate a byte array byte buffer [] = new byte [1024]; // 4. call the read method of the input stream object to return the data size while (true) {int temp = fiis. read (buffer, 0, buffer. length); If (temp =-1) {break;} FOS. write (buffer, 0, temp) ;}} catch (exception e) {system. out. println (E);} finally {try {// 5. // close the input/output stream. close (); FOS. close ();} catch (exception e) {system. out. println (e );}}}}

Example 2: Use of the ghost stream [file copy]

// File copy: // 1. import Io package // 2. generate the object representing the input stream // 3. generate a byte array // 4. call the read method of the input stream object to return the data size // 5. // close the input/output stream package Tan; import Java. io. filereader; import Java. io. filewriter; import Java. io. ioexception; import javax. management. runtimeerrorexception; public class readfile {public static void main (string [] ARGs) {filereader Fr = NULL; filewriter fw = NULL; try {Fr = new filereader ("C: /users/Administrator/workspace1/20140727/src/TaN/F Iletest. java "); fw = new filewriter (" to.txt "); char Buf [] = new char [1024]; // The first method int Len = 0; while (LEN = Fr. read (BUF ))! =-1) {FW. Write (BUF, 0, Len);} system. Out. println ("file copied successfully! "); // Method 2 // while (true) {// int temp = Fr. read (BUF, 0, Buf. length); // If (temp =-1) {// break; //} // FW. write (BUF, 0, temp); //} catch (exception e) {Throw new runtimeexception ("file copy failed! ");} Finally {try {Fr. close (); FW. close ();} catch (exception e) {e. tostring () ;}}}// public void write (char [] cbuf, int off, int Len) throwsioexception writes a part of the character array.