I/O流实操

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创建与文件关联的字节输出流对象 FileOutputStream fos = new
FileOutputStream("c:\\cn8.txt"); //创建可以把字符转成字节的转换流对象，并指定编码
OutputStreamWriter osw = new OutputStreamWriter(fos,"utf-8");
调用转换流，把文字写出去，其实是写到转换流的缓冲区中 osw.write("你好");//写入缓冲区。 osw.close();
创建读取文件的字节流对象

InputStream in;
       try {
           in = new FileInputStream("d:/aa/5.txt");
 
           // 创建转换流对象
           // InputStreamReader isr = new
           // InputStreamReader(in);这样创建对象，会用本地默认码表读取，将会发生错误解码的错误
           InputStreamReader isr = new InputStreamReader(in, "gbk");
           // 使用转换流去读字节流中的字节
           int ch = 0;
           while ((ch = isr.read()) != -1) {
               System.out.println((char) ch);
           }
           // 关闭流
           isr.close();
       } catch (FileNotFoundException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       } catch (UnsupportedEncodingException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       } catch (IOException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }

字符输出流

// TODO Auto-generated method stub
 
        File file = new File("d:/aa/5.txt");
 
        try {
            // 字符输出流
            FileWriter fileWriter = new FileWriter(file, true); // 字符输出流
                                                                // true代表追加
 
            fileWriter.write("你好");
 
            fileWriter.close();
 
            // 字节输出流
 
            FileOutputStream fileOutputStream = new FileOutputStream(file, true);
 
            fileOutputStream.write('a');
 
            fileOutputStream.close();
 
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
点击并拖拽以移动

字符输入流

//字符输入流  读  文本文件的读写(.java .txt...)
       //1.创建对象
       File file=new File("d:/aa/4.txt");
        
       //2.创建字符输入流对象
       try {
           FileReader fileReader=new FileReader(file);
           int a;
            
           a= fileReader.read(); //读取一个字符
            
           System.out.println((char)a);
            
           char[] arr=new char[3];
            
           fileReader.read(arr);//读取多个字符到数组中
            
           System.out.println(new String(arr));
            
           //循环读取文件的内容
           while((a=fileReader.read())!=-1)
               System.out.println((char)a);
            
           fileReader.close();
            
       } catch (FileNotFoundException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       } catch (IOException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
       

字符输出流+文件

        //字符输出流  写出
       //1.创建文件对象
        File file=new File("d:/aa/5.txt");
        //2.创建字符输出流
        try {
             
            FileWriter fileWriter=new FileWriter(file);
             
            fileWriter.write("bb\r\n"); //换行  
             
            fileWriter.write("呆萌");
             
            fileWriter.close();
             
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
         
        
点击并拖拽以移动
//字节输入流  从文件中读数据进来 一个字节一个字节的读取    (图片 视频文件的读写)
        //(一个英文字符或数字字符对应一个字节 一个中文字对应的是两个字节,所以读中文要用字符流)      
        //1.创建文件对象
        File file=new File("d:/aa/2.txt");      
        //2.创建一个输入流对象
        try {
             
            FileInputStream fileInputStream=new FileInputStream(file);
             
            //3.读数据
            int a=fileInputStream.read(); //读取下一个字符  读到了返回当前字符的ascII码 读到文件结尾 则返回-1
             
            System.out.println((char)a);
             
            a=fileInputStream.read();
             
            System.out.println((char)a);
             
            //读取多个字节到数组中
            byte[] arr=new byte[3];
            fileInputStream.read(arr); //读取3个字节存入arr数组中
             
            System.out.println(new String(arr, 0, 3));
             
            //读取整个文件
            while((a=fileInputStream.read())!=-1)
                System.out.print((char)a);              
            //关闭文件
            fileInputStream.close();
             
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
         
        

字节输出流+文件操作

//字节输出流  将数据写到文件中
         
        //1.创建文件对象
       File file=new File("d:/aa/3.txt");
        
         //2.创建字节输出流
       try {
         
           FileOutputStream fileOutputStream=new FileOutputStream(file);
            
           //3.写内容
           fileOutputStream.write('a'); //一次写入一个字节
            
           byte[] arr=new byte[]{'b','c','d'}; //写入一个byte类型的数组
            
           String string="daimeng";
            
           byte[] brr=string.getBytes(); //可以将字符串转换为字节数组
            
           fileOutputStream.write(brr);
            
           fileOutputStream.close(); //关闭流   
            
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }