Input stream in io stream

io Stream profile

i:input o:output
io Stream is used to deal with the problem of device data transmission
Input stream ： Reading data
Output stream ： Writing data
Byte stream ： Byte input stream , Byte output stream
Character stream ： Character input stream , Character output stream
If the data passes through window The self-contained Notepad can be opened , The content inside can be read , Is the character stream
No, it's byte stream （ If you don't know what to use, use byte stream ）

Byte input stream （ Writing data ）

Steps to write data using byte output stream ：
1, Call the system to create a file
2, Created byte output stream object
3, Let the byte output stream object point to the created file

 // Create byte stream output stream object 
        //FileOutputStream (String name), Create a file output stream and write the specified name to the file 
        //IDEA Default myByteStream So you don't have to enter 
        FileOutputStream fos =new FileOutputStream("fos.txt");

        //void write(int b)：  Write the specified bytes to this file output stream 
        fos.write(97);
        fos.write(57);
        fos.write(55);

        // In the end, we need to release resources 
        //void close(), Close this file output stream / And release any system resources related to this flow 
        fos.close();

How to write data

// The first way is to write directly 
        fos.write(97);
        fos.write(98);
        fos.write(99);
        fos.write(100);
        
        // The second way is to write data through the situation of the array 
        void write(byte[] b); take b.length Byte writes the output stream of this file from the specified byte array 
        byte[]bys={
    97,98,87,99,100};
        fos.write(bys);

         // Write by string 
        byte[]getBytes(), Returns the byte array corresponding to the string 
        byte[] bys="abcde".getBytes();
        fos.write(bys);
         // Write data at the specified position and length 
        //void write (byte[] b,int off,int len);byte[] b Is the name of the specified array ,
        //int off Index subscript ,int len Refers to the length of the written data ;
       //  example （1,3） Is to write the index in the array as 1 The next three numbers are 1 The index for ,2,3
        byte[]bys={
    97,98,87,99,100};
        fos.write(bys,1,3);
        
        // Standard way of writing data 
        for (int i = 0; i < 10; i++) {
    
            fos.write("hello".getBytes());
            fos.write("\n".getBytes());
        }
        fos.close();

Append write data

// From a to Z , Rewrite all data , Overlay the previous data
FileOutputStream fos =new FileOutputStream(“fos.txt”);
// Add data from the end
FileOutputStream fos =new FileOutputStream(“fos.txt”,true);

Exception handling and judge to close resources

try {
    
            FileOutputStream fos = new FileOutputStream("fos.txt", true);
            // Write data 
            for (int i = 0; i < 10; i++) {
    
                fos.write("hello".getBytes());
                fos.write("\n".getBytes());
            }
            if(fos!=null){
    
                fos.close();
            }
        }catch (IOException e){
    
            e.printStackTrace();
        }