IO stream code

 

Catalog

 FileInputStrea Byte input stream

 FileOutputStream Byte output stream

FileReader Character input stream  

 FileWriter Character output stream

  Copy ： Use FileInputStream + FileOutputStream Complete the copy of the file .

  Use FileReader FileWriter If you copy , You can only copy “ Plain text ” file .

---

 FileInputStrea Byte input stream

package com.bjpowernode.java.io;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

/*
 The final version , Need to master .
 */
public class FileInputStreamTest04 {
    public static void main(String[] args) {
        FileInputStream fis = null;
        try {
            fis = new FileInputStream("chapter23/src/tempfile3");
            //  Prepare one byte Array 
            byte[] bytes = new byte[4];
            /*while(true){
                int readCount = fis.read(bytes);
                if(readCount == -1){
                    break;
                }
                //  hold byte Array to string , How many conversions do you read .
                System.out.print(new String(bytes, 0, readCount));
            }*/

            int readCount = 0;
            while((readCount = fis.read(bytes)) != -1) {
                System.out.print(new String(bytes, 0, readCount));
            }

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

 FileOutputStream Byte output stream

package com.bjpowernode.java.io;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 *  File byte output stream , Responsible for writing .
 *  From memory to hard disk .
 */
public class FileOutputStreamTest01 {
    public static void main(String[] args) {
        FileOutputStream fos = null;
        try {
            // myfile When the file does not exist, it will be created automatically ！
            //  It's a way to use it with caution , In this way, the original file will be emptied first , And then rewrite it .
            //fos = new FileOutputStream("myfile");
            //fos = new FileOutputStream("chapter23/src/tempfile3");

            //  Write... At the end of the file by appending . The contents of the original file will not be emptied .
            fos = new FileOutputStream("chapter23/src/tempfile3", true);
            //  Start writing .
            byte[] bytes = {97, 98, 99, 100};
            //  take byte The array is all written out ！
            fos.write(bytes); // abcd
            //  take byte Part of the array writes ！
            fos.write(bytes, 0, 2); //  Write again ab

            //  character string 
            String s = " I am a Chinese , I'm proud of ！！！";
            //  Converts a string to byte Array .
            byte[] bs = s.getBytes();
            //  Write 
            fos.write(bs);

            //  After you've written , Finally, we must refresh 
            fos.flush();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

FileReader Character input stream  

package com.bjpowernode.java.io;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

/*
FileReader：
     File character input stream , Only plain text can be read .
     When reading text content , It's more convenient , quick .
 */
public class FileReaderTest {
    public static void main(String[] args) {
        FileReader reader = null;
        try {
            //  Create a file character input stream 
            reader = new FileReader("tempfile");

            // Prepare one char Array 
            char[] chars = new char[4];
            //  Go to char Read in array 
            reader.read(chars); //  Read in character ： for the first time e, The second time f, third time   wind ....
            for(char c : chars) {
                System.out.println(c);
            }

            /*//  Start reading 
            char[] chars = new char[4]; //  Read once 4 Characters 
            int readCount = 0;
            while((readCount = reader.read(chars)) != -1) {
                System.out.print(new String(chars,0,readCount));
            }*/
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

 FileWriter Character output stream

package com.bjpowernode.java.io;

import java.io.FileWriter;
import java.io.IOException;

/*
FileWriter:
     File character output stream . Write .
     Only plain text can be output .
 */
public class FileWriterTest {
    public static void main(String[] args) {
        FileWriter out = null;
        try {
            //  Create a file character output stream object 
            //out = new FileWriter("file");
            out = new FileWriter("file", true);

            //  Start writing .
            char[] chars = {' I ',' yes ',' in ',' countries ',' people '};
            out.write(chars);
            out.write(chars, 2, 3);

            out.write(" I am a java Software engineer ！");
            //  Write a newline character .
            out.write("\n");
            out.write("hello world!");

            //  Refresh 
            out.flush();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

  Copy ： Use FileInputStream + FileOutputStream Complete the copy of the file .

package com.bjpowernode.java.io;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

/*
 Use FileInputStream + FileOutputStream Complete the copy of the file .
 The process of copying should be reading , While writing .
 When using the above byte stream to copy files , The file type is arbitrary , Omnipotent . Any kind of file can be copied .
 */
public class Copy01 {
    public static void main(String[] args) {
        FileInputStream fis = null;
        FileOutputStream fos = null;
        try {
            //  Create an input stream object 
            fis = new FileInputStream("D:\\course\\02-JavaSE\\video\\chapter01\\ Power nodes -JavaSE- Du Jubin -001- Display of file extension .avi");
            //  Create an output stream object 
            fos = new FileOutputStream("C:\\ Power nodes -JavaSE- Du Jubin -001- Display of file extension .avi");

            //  At the core of ： While reading , While writing 
            byte[] bytes = new byte[1024 * 1024]; // 1MB（ Most copies at a time 1MB.）
            int readCount = 0;
            while((readCount = fis.read(bytes)) != -1) {
                fos.write(bytes, 0, readCount);
            }

            //  Refresh , The output stream is finally refreshed 
            fos.flush();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //  Separate try, Not together try.
            //  Together try When , One of them has an exception , It may affect the closing of another flow .
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

  Use FileReader FileWriter If you copy , You can only copy “ Plain text ” file .

package com.bjpowernode.java.io;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

/*
 Use FileReader FileWriter If you copy , You can only copy “ Plain text ” file .
 */
public class Copy02 {
    public static void main(String[] args) {
        FileReader in = null;
        FileWriter out = null;
        try {
            //  read 
            in = new FileReader("chapter23/src/com/bjpowernode/java/io/Copy02.java");
            //  Write 
            out = new FileWriter("Copy02.java");

            //  Read and write ：
            char[] chars = new char[1024 * 512]; // 1MB
            int readCount = 0;
            while((readCount = in.read(chars)) != -1){
                out.write(chars, 0, readCount);
            }

            //  Refresh 
            out.flush();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}