二进制I/O

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;

public class TextCode {
    public static void main(String[] args) throws IOException {
        
        DataOutputStream output = new DataOutputStream(
                new BufferedOutputStream(new FileOutputStream("data.dat")));
        output.writeChar('a');
        output.writeInt(5);//int型32位
        output.writeInt(16);/*十六进制显示：00 61 00 00 00 05 00 00 00 10*/
        output.flush();//当缓冲区填满或当流被清空时，数据就被写出。
        DataInputStream input = new DataInputStream(
                new BufferedInputStream(new FileInputStream("data.dat")));
        System.out.println(input.readChar());
        System.out.println(input.readInt());
        System.out.println(input.readInt());
        output.close();
        input.close();
        PrintWriter out = new PrintWriter("text.txt");
        out.println("你好");
        out.println("Hello");
        out.print(10);/*十六进制显示：
        C4 E3 BA C3 0D OA 48 65 6C 6C 6F 0D 0A 31 30*/
        out.close();//如果没有调用该方法，数据就不能正确地保存在文件中
    }
}

 

FileInputStream和FileOutputStream类：是为了从/向文件读取/写入字节。

FilterInputStream类和FilterOutputStream类：过滤器数据流。

DataInputStream类（从数据流读取字节，并且把它们转换为正确的基本类型或字符串）和DataOutputStream类（将基本类型的值或字符串转换成字节，并且将字节输出到数据流）

• +readByte():byte    +writeByte(v: int):void
• +readDouble():double    +writeDouble(v: double):void
• +writeChar(c: char): void 向输出流写入一个字符（由两个字节组成）
• +writeChars(s: String): void

BufferedInputStream类和BufferedOutputStream类为存储字节在流中添加一个缓冲区，以提高处理效率。

• BufferedInputStream(int: InputStream)
• BufferedOutputStream(filename:String, bufferSize: int)

ObjectInputStream类和ObjectOutputStream类：对象的输入输出。

• ObjectInputStream(in: InputStream)
• ObjectOutputStream(out: OutputStream)

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;


public class Test {
    public static void main(String[] args) throws IOException {
        BufferedReader in;
        try {
            //FileReader会抛出异常
            in = new BufferedReader(new FileReader("text.txt"));
            System.out.println(in.readLine());
            in.close();
        } catch (IOException e) {
        }
        try {
            Scanner input = new Scanner(new File("text.txt"));
            System.out.println(input.nextLine());
            input.close();
        } catch (FileNotFoundException e) {
        }
        /*BufferedReader从字符输入流中读取文本，缓冲各个字符，从而实现字符、数组和行的高效读取。*/
        /*InputStreamReader类将包含字节（用某种字符编码方式表示的字符）的输入流转换为可以产生Unicode字符的读入器*/
        BufferedReader inp = new BufferedReader(new InputStreamReader(System.in));//字符的读取
        Scanner input1 = new Scanner(System.in);//从键盘输入
        try{
            FileInputStream fileInput = new FileInputStream("text.txt");//只能读入字节和字节数组
            /*默认不使用缓冲区*/
            DataInputStream din = new DataInputStream(fileInput);//可以读取数据类型Byte,Int,Char,Double...
            /*嵌套过滤器来添加多重功能*/
            DataInputStream dInput = new DataInputStream(
                    new BufferedInputStream(new FileInputStream("text1.txt")));
            System.out.println(dInput.readChar());
            
        }
        catch(FileNotFoundException e){
        }
        try {
            FileReader fileReader = new FileReader("tetx.txt");
        } catch (Exception e) {
        }    
    }

}