Simple example of using java to read/write text files, java example

Simple example of using java to read/write text files, java example
/*
* Simple example of reading/writing text files
* There are three examples:
* 1. Example of reading a file into memory (StringBuffer here)
* 2. Write the text in the content to a file
* 3. Read the content of one file and write it to another file.
* It also shows that if the content read from the input stream is written to the output stream (Text Stream only)
* The three examples can exist independently, so you can only view one of them as needed.
*/

Import java. io. BufferedReader;
Import java. io. FileInputStream;
Import java. io. FileOutputStream;
Import java. io. IOException;
Import java. io. InputStream;
Import java. io. InputStreamReader;
Import java. io. OutputStream;
Import java. io. OutputStreamWriter;
Import java. io. PrintStream;
Import java. io. PrintWriter;

Public final class AccessTextFile {

/**
* 1. Read the text in the stream into a StringBuffer.
* @ Throws IOException
*/
Public void readToBuffer (StringBuffer buffer, InputStream is)
Throws IOException {
String line; // used to save the content read by each row
BufferedReader reader = new BufferedReader (new InputStreamReader (is ));
Line = reader. readLine (); // read the first row
While (line! = Null) {// If line is null, the read is complete.
Buffer. append (line); // Add the read content to the buffer.
Buffer. append ("\ n"); // Add a line break
Line = reader. readLine (); // read the next row
}
}

/**
* 2. Demonstrate reading the content in StringBuffer into the stream
*/
Public void writeFromBuffer (StringBuffer buffer, OutputStream OS ){
// Use PrintStream to conveniently output content to the output stream
// Its object usage is the same as that of System. out.
// (System. out itself is a PrintStream object)
PrintStream ps = new PrintStream (OS );
Ps. print (buffer. toString ());
}

/**
* 3 *. Copy the content from the input stream to the input stream.
* @ Throws IOException
*/
Public void copyStream (InputStream is, OutputStream OS) throws IOException {
// For the read process, see the comments in readToBuffer.
String line;
BufferedReader reader = new BufferedReader (new InputStreamReader (is ));
PrintWriter writer = new PrintWriter (new OutputStreamWriter (OS ));
Line = reader. readLine ();
While (line! = Null ){
Writer. println (line );
Line = reader. readLine ();
}
Writer. flush (); // finally, make sure to write everything in the output stream.
// Writer is not disabled because the OS is passed in from outside.
// Since it is not opened from here, it will not be closed from here
// If the writer is closed, the OS encapsulated in it will be shut down.
}

/**
* 3. Call the copyStream (InputStream, OutputStream) method to copy text files.
*/
Public void copyTextFile (String inFilename, String outFilename)
Throws IOException {
// Generate the corresponding input/output stream based on the input/output file
InputStream is = new FileInputStream (inFilename );
OutputStream OS = new FileOutputStream (outFilename );
CopyStream (is, OS); // use copyStream to copy content
Is. close (); // is enabled here, so you need to close
OS. close (); // OS is enabled here, so you need to disable
}

Public static void main (String [] args) throws IOException {
Int sw = 1; // three test options
AccessTextFile test = new AccessTextFile ();

Switch (sw ){
Case 1: // test read
{
InputStream is = new FileInputStream ("E: \ test.txt ");
StringBuffer buffer = new StringBuffer ();
Test. readToBuffer (buffer, is );
System. out. println (buffer); // write the content in the buffer.
Is. close ();
Break;
}
Case 2: // test write
{
StringBuffer buffer = new StringBuffer ("Only a test \ n ");
Test. writeFromBuffer (buffer, System. out );
Break;
}
Case 3: // test copy
{
Test. copyTextFile ("E: \ test.txt", "E: \ r.txt ");
}
Break;
}
}

}