Io流之字节流的介绍及用法

package Io流;

import org.junit.Test;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

public class Demo03 {
    /**
     * 输入流
     * 1.字节输入流    InputStream
     *     1.1 FileInputStream(File file)  推荐  read();
     *         FileInputStream(pathName)
     *     1.2 BufferInputStream
     *     创建数据
     *     铺设管道
     *     开水龙头
     *     关水龙头
     *
     * 2.字节输出流
     *      2.1 FileOutputStream(pathName)
     *          FileOutputStream(pathName，true)
     *          write(); close();
     *      2.2 BufferedOutputStream
     *      创建数据
     *      铺设管道
     *      开水龙头
     *      关水龙头
     */
//    FileInputStream(File file)
    @Test
    public void test(){
        try {
            File file = new File("d:\\11.txt");
            if (file.exists() && file.length()>0){
                FileInputStream fis = new FileInputStream(file);
                int ch = fis.read();
                System.out.println(ch);
                fis.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    @Test
    public void test1(){
        try {
            File file = new File("d:\\11.txt");
            if (file.exists() && file.length()>0){
                FileInputStream fis = new FileInputStream(file);
                int ch = 0;
                while ((ch =fis.read()) != -1){
                    System.out.print((char)ch);
                }
                fis.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
//覆盖原文件
    @Test
    public void test3(){
        try {
            String str = "not beautiful";
            File file = new File("d:\\11.txt");
            FileOutputStream fos = new FileOutputStream(file,true);
            //write()  如果文件不存在，自动创建
            fos.write(str.getBytes());
            fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}