io流 字节文件流FileOutputStream与FileInputStream实现

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import java.io.*;


/**
 * Created by lxj-pc on 2017/6/25.
 */
public class WriterJavaApp {
    public static void main(String[] args) {
        String fileName="Hello.java";
        String dirPath="d:/demo/day01";
        //java.io.File
        File dir=new File(dirPath);
        if(!dir.exists())
            dir.mkdirs();

        //字节文件流：FileOutputStream
        //字符文件流：FileWriter


        try {
            FileOutputStream  fos = new FileOutputStream(new File(dir,fileName));
            fos.write("public class Hello{\r\n".getBytes());
            fos.write("public static void main(String[] args) {\r\n".getBytes());
            fos.write("System.out.prinntln(\"你好\");\r\n".getBytes());
            fos.write("}".getBytes());
            fos.write("}".getBytes());
            fos.close();

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }


        System.out.println("写入成功！");

        readTxt(dirPath+"/"+fileName);



    }
//读取指定绝对路径文件的文本内容 filePath



    public static void readTxt(String  filePath) {
        //文件字符流  FileReader
        //文件字节流 FIS
        File file =new File(filePath);
        if(!file.exists()){
            System.out.println(filePath+"不存在文件");


        }


        try {
            FileInputStream fis= null;
            fis = new FileInputStream(file);
            byte[] bytes= new byte[0];
            try {
                bytes = new byte[fis.available()];
            } catch (IOException e) {
                e.printStackTrace();
            }

            try {
                fis.read(bytes);
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                fis.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            System.out.println("读完");
            System.out.println(new String(bytes));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }



    }


}

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