(Byte stream and character stream) conversion stream

Conversion flow

Conversion stream refers to the functional conversion that can realize byte stream and character stream operations. For example, when outputting, OutputStream needs to change the content into a byte array and then output it, and Writer can directly output strings, so many people think that it needs a A conversion mechanism to realize the conversion operation of different stream types. For this reason, there are two classes in the java.io package:

• InouterSteamReader

//定义
public class InputStreamReader extends Reader
//构造方法
public InputStreamReader​(InputStream in)

 

• OutputStreamWriter

//定义
public class OutputStreamWriter extends Writer
//构造方法
public OutputStreamWriter​(OutputStream out)

Incoming byte stream object, use up-cast to convert bit character stream object.

Example: Observe the conversion

public class Writer字符流输出 {
    public static void main(String[] args) throws IOException {
        File file = new File("F:"+File.separator+"Test"+File.separator+"test.txt");
        if(file.getParentFile().exists()){  //没有父路径
            file.getParentFile().mkdirs();  //创建一个父路径
        }
        OutputStream outputStream = new FileOutputStream(file);
        Writer writer = new OutputStreamWriter(outputStream);   //字节流变为了字符流
        writer.write("www.baidu.com");  //直接输出一个字符串，不需要转换为字节数组
        writer.close();
    }
}

The OutputStream class has a direct subclass of FileOutputStream, and InputStream has a direct subclass of FileInputstream, but let’s observe the inheritance relationship between FileWriter and FileReader:

//FileWrite
public class FileWriter extends OutputStreamWriter

//FileReader
public class FileReader extends InputStreamReader

FileReader inheritance structure

The difference between character stream and byte stream is that the character stream has more buffers, which actually refers to a processing buffer in the middle of the program.