流的新认知

【1】File类操作

list()：所有的子文件和子目录名称

listFiles()：所有的子文件和子目录File对象

getParent():父目录的名称

getParentFile():父路径的文件对象

【2】FileInput\FileOutput操作——字节流

抛异常：【字符流同理：OutputStreamWriter || InputStreamReader】

--- FileNotFouondException ——创建FIle();或者 new FileOutputStream()时候

---IOException: FileOutputStream调用 write（）方法时候。

---try…catch() 也可以catch 自己抛的异常

获取当前流中可读字节数：说明了流的本质就是数组，获取数组的长度，只不过采用不同类型数组：byte[]\char[]

byte[] bs = new byte[in.available()];//获取当前流当中，该文件可读字节数

【3】字符流

区别于：字节流的读写[write.flush()]

FileOutputStream || FileInputStream

---单字节写入write(byte) &&& 字节数组写入 write(byte[])

    单字符写入write(char) &&& 字符数组写入或字符串写入 write(String) write(char[])

OutPutStreamWriter || InputStreamReader

---单字节读取read() &&& 字节数组读取 read(byte[]) // 长度：从inputStream流中获取 avaiable()

    单字符读取 read() &&& 字符数组读取 read(char[]) //长度上: 从WinNTFileSystem类获取文件长度 getLength()

BufferedOutPutStream && BufferedInputStream ——作用增加缓冲

---单字节写入write(byte) &&& 字节数组写入 write(byte[])

---单字节读取read() &&& 字节数组读取 read(byte[]) // 长度：从inputStream流中获取 avaiable()

BufferedWriter || BufferedReader

---write(String) && write(char[],off,len)

---reade(char[]) && read()-返回int && readLine() --返回字符串

【note】关系梳理：

BufferedReader(new InputStreamReader(new FileInputStream(File)))

InputStreamReader(new FileInputStream(File)) && BufferedOutputStream(new FileOutputStream())

new FileInputStream(File)

【4】ObjectOutputStream \ ObjectInputStream 对象输入输出流 &&& 深浅复制的序列化【字节序列化ByteArrayOutputStream + ObjectOutputStream】 &&& DataOutputStream \ DataInputStream

---ObjectOutputStream(new FileOutputStream(f))

    writeObject(对象)

---DataOutputStream(new FileOutputStream(f)); 【注意：读写的顺序必须保障一致】

    writeInt\Short\UTF(字符串)

Java文件类中好多都是不可见：

FileInputStream—available()

WinNTFileSystem—getLength()

DataInputStream\DataOutputStream在网络编程中的应用：

客户端：

Socket socket = new Socket("127.0.0.1", 8080);
//发送请求
OutputStream outputStream = socket.getOutputStream();
DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
String request = "客户端请求信息：hello server http ip";
dataOutputStream.writeUTF(request);
//接受请求
InputStream inputStream = socket.getInputStream();
DataInputStream dataInputStream = new DataInputStream(inputStream);
String response = dataInputStream.readUTF();
System.out.println("客户端获得响应信息："+response);

服务端：

serverSocket = new ServerSocket(8080);
Socket socket = serverSocket.accept();
InputStream inputStream = socket.getInputStream();
DataInputStream dataInputStream = new DataInputStream(inputStream);
String receive = dataInputStream.readUTF();
System.out.println("服务端接收到消息："+receive);
//反馈
String response = "hello client:protocal TCP\\IP";
OutputStream outputStream = socket.getOutputStream();
//outputStream.write(response.getBytes());
DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
dataOutputStream.writeUTF(response);
System.out.println("服务端给客户端作出响应："+response);

字节序列化问题

        Person person = new Person();
         person.setAge(18);
         person.setName("macro");
         ByteArrayOutputStream bOutputStream = new ByteArrayOutputStream();
         ObjectOutputStream outputStream = new ObjectOutputStream(bOutputStream);
         outputStream.writeObject(person);

         ByteArrayInputStream bInputStream = new ByteArrayInputStream(bOutputStream.toByteArray());
         ObjectInputStream oInputStream = new ObjectInputStream(bInputStream);
         Object obj = oInputStream.readObject();
         if (obj instanceof Person) {
             Person person2 = (Person)obj;
             System.out.println(person2);
         }

数组引用地址：流读取到数组，更改引用地址即可！不需要返回值！

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