407 lines
12 KiB
Markdown
407 lines
12 KiB
Markdown
<!-- GFM-TOC -->
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* [????](#????)
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* [???????](#???????)
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* [??????](#??????)
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* [???????](#???????)
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* [???????](#???????)
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* [???????](#???????)
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* [1. InetAddress](#1-inetaddress)
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* [2. URL](#2-url)
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* [3. Sockets](#3-sockets)
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* [4. Datagram](#4-datagram)
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* [NIO](#nio)
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* [1. ?????](#1-?????)
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* [2. ?????????](#2-?????????)
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* [2.1 ???](#21-???)
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* [2.2 ??????](#22-??????)
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* [3. ????????????](#3-????????????)
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* [4. ??§Õ??????](#4-??§Õ??????)
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* [5. ???????????](#5-???????????)
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* [5.1 ????? I/O](#51-?????-io)
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* [5.2 ??????? I/O](#52-???????-io)
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* [6. ????????](#6-????????)
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* [6.1 ServerSocketChannel](#61-serversocketchannel)
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* [6.2 Selectors](#62-selectors)
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* [6.3 ?????](#63-?????)
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* [6.4 ??????????](#64-??????????)
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* [6.5 ???????????](#65-???????????)
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* [6.6 ?????????? SelectionKey](#66-??????????-selectionkey)
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* [6.7 ????? I/O](#67-?????-io)
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* [?¦Ï?????](#?¦Ï?????)
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<!-- GFM-TOC -->
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# ????
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Java ?? I/O ???????????????
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1. ?????????File
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2. ????????InputStream ?? OutputStream
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3. ?????????Reader ?? Writer
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4. ?????????Serializable
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5. ?????????Socket
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6. ??????? IO??NIO
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# ???????
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File ????????????????????????????????????????????????????????????
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# ??????
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Java I/O ???????????????????? InputStream ?????InputStream ??????????FileInputStream ?? InputStream ??????????????????????????????????????FilterInputStream ????????????????????????????????????????????????? BufferedInputStream ? FileInputStream ??????????????????????§Ý??œ¤????????????????????? FileInputStream ????????????? BufferedInputStream ????¨À?
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```java
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BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));
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```
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DataInputStream ?????????????????????????????????????? int??double ??????????
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????????????§Ö???????????????
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```java
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byte[] buf = new byte[20*1024];
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int bytes = 0;
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// ????? buf.length ????????????????????????????? -1 ??????????? eof???????¦Â
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while((bytes = in.read(buf, 0 , buf.length)) != -1) {
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// ...
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}
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```
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# ???????
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???????????????×Ï????§³??›¥?????????????????????????? I/O ????????????????????????????????§Ó??????????????????????????????????????§Ó??????????
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InputStreamReader ?????????????????????????????OutputStreamWriter ??????????????????????????????????????? Reader ?? Writer??
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????????????????????????????????????????????
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```java
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byte[] bytes = str.getBytes(encoding); // ????
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String str = new String(bytes, encoding)?? // ????
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```
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GBK ?????§µ?????? 2 ?????????? 1 ??????UTF-8 ?????§µ?????? 3 ?????????? 1 ??????Java ?????????? UTF-16be???????????? 2 ??????
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????????????????¨°??????????????????????
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# ???????
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???§Ý????????????????????????§µ?????›¥?????
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???§Ý???ObjectOutputStream.writeObject()
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?????§Ý???ObjectInputStream.readObject()
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???§Ý??????????? Serializable ?????????????????????¦Ê¦Ç??????????
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transient ??????????§»??????????§Ý???
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**ArrayList ???§Ý???????§Ý??????**??ArrayList ?§Õ›¥????????????? transient ???¦Å???????????????????????????????§Ö????????????????????§Ö???????????§Ý????????§Õ???§Ý???????§Ý?????????????????§Ý????????????????????????
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```
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private transient Object[] elementData;
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```
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# ???????
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Java ?§Ö?????????
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1. InetAddress????????????????????????? IP ?????
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2. URL?????????¦Ë??????? URL ?????????????§Õ??????????????
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3. Sockets????? TCP §¿?????????????
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4. Datagram????? UDP §¿?????????????
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## 1. InetAddress
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??§Û??§Û??????????????????????????????????? InetAddress.getByName(String host)??InetAddress.getByAddress(byte[] addr)??
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## 2. URL
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???????? URL ?§Ø???????????
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```java
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URL url = new URL("http://www.baidu.com");
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InputStream is = url.openStream(); // ?????
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InputStreamReader isr = new InputStreamReader(is, "utf-8"); // ?????
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BufferedReader br = new BufferedReader(isr);
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String line = br.readLine();
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while (line != null) {
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System.out.println(line);
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line = br.readLine();
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}
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br.close();
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isr.close();
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is.close();
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```
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## 3. Sockets
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Socket ??????
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- ServerSocket????????????
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- Socket?????????
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??????????????? InputStream ?? OutputStream ?????????????
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## 4. Datagram
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- DatagramPacket?????????
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- DatagramSocket???????
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# NIO
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NIO ???????? I/O ???? ( ??????????????? ) ?????????????? ??????????????????????????????????
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## 1. ?????
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I/O ?? NIO ?????????????????????????????????????????I/O ??????????????????? NIO ???????????????
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???????? I/O ???????????§Õ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? I/O ?????????
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????????? I/O ??????????????????????????????????§Ó??????????????????î•???ø„????????????????????????????????? I/O ????§»???????? I/O ?????§Ö????????????
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I/O ???? NIO ?????????????java.io.\* ????? NIO ????????????????????????????????? NIO ???§»????????íà java.io.\* ???§Ö??§»??????????????§Õ??????????????¨¹????????????????§µ??????????????
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## 2. ?????????
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### 2.1 ???
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??? Channel ???? I/O ???§Ö??????????????????????§Õ???????
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????????????????????????????????????????(??????????? InputStream ???? OutputStream ??????)?? ???????????????????????§Õ???????????§Õ??
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????????????????
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- FileChannel????????§Ø?§Õ?????
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- DatagramChannel????? UDP ??§Õ???????????
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- SocketChannel????? TCP ??§Õ???????????
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- ServerSocketChannel???????????????? TCP ?????????????????????????????? SocketChannel??
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### 2.2 ??????
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????????????????§Ø???????????????????§µ?????????????§Ø?????¦Ê??????????????????§³???????????????????????§Ø?§Õ??????????????????????
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???????????????????ï…??????????????????î•?????????????????????????????????????????/§Õ?????
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???????????????????
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- ByteBuffer
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- CharBuffer
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- ShortBuffer
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- IntBuffer
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- LongBuffer
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- FloatBuffer
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- DoubleBuffer
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## 3. ????????????
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- capacity???????????
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- position??????????§Õ?????????
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- limit?????????§Õ?????????
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??????????????
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1\. ????????§³? 8 ???????????????? position ? 0???? limit == capacity == 9??capacity ???????????????????????????
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2\. ??????????§Ø?? 3 ?????????§Õ???????§µ???? position ?????? 3??limit ???????
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3\. ???????????????§Õ???????????????????? flip() ??????????????? limit ???????? position?????? position ????? 0??
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4\. ?????????? 4 ??????????????§µ???? position ??? 4??
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5\. ?????????? clear() ??????????????????? position ?? limit ????????????¦Ë?¨¢?
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## 4. ??§Õ??????
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1\. ?????????????? FileInputStream???????? FileInputStream ??????? FileChannel??
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```java
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FileInputStream fin = new FileInputStream("readandshow.txt");
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FileChannel fic = fin.getChannel();
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```
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2\. ???????????? 1024 ?? Buffer
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```java
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ByteBuffer buffer = ByteBuffer.allocate(1024);
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```
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3\. ??????????? FileChannel §Õ?? Buffer ?§µ??????????????? read() ???????? -1
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```java
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int r = fcin.read(buffer);
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if (r == -1) {
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break;
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}
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```
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4\. ??§Õ?????????? FileOutputStream???????? FileOutputStream ?????? FileChannel
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```java
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FileOutputStream fout = new FileOutputStream("writesomebytes.txt");
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FileChannel foc = fout.getChannel();
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```
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5\. ???? flip() ?§Ý???§Õ
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```java
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buffer.flip();
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```
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6\. ?? Buffer ?§Ö???????????? FileChannel ??
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```java
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foc.write(buffer);
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```
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7\. ?????? clear() ?????????
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```java
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buffer.clear();
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```
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## 5. ???????????
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??????FileChannel ?????§Ý?????????????????? Channel ?????
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### 5.1 ????? I/O
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????? I/O ????? InputStream.read() ?????????????????????????????????????? ServerSocket.accept() ???????????????????§á??????????????????????????????????????????????????????????????
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### 5.2 ??????? I/O
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?????????????????????§Ö? I/O ???????????????
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??????????????????????????????????????????????
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???????????????? wait()??notify() ?????????????????????§Ý???????????????????¦Í??????§Ý???
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## 6. ????????
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### 6.1 ServerSocketChannel
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???????????????? ServerSocketChannel ?????????????
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```java
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ServerSocketChannel ssc = ServerSocketChannel.open();
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ssc.configureBlocking(false); // ???????????
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ServerSocket ss = ssc.socket();
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InetSocketAddress address = new InetSocketAddress(ports[i]);
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ss.bind(address); // ?????
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```
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### 6.2 Selectors
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?? I/O ??? Selector ??????? I/O ???????? ?D ?????????????????????????????????????????????????????????
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???? Selectors ?????????????????????? register() ??????register() ????????????????? Selector????????????? OP_ACCEPT?????????????????????? accept ????????????????????????????????????
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SelectionKey ????????????? Selector ?????????????? Selector ????????????????????????????????????? SelectionKey ?????§Ö??SelectionKey ?????????????????????
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```java
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Selector selector = Selector.open();
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SelectionKey key = ssc.register(selector, SelectionKey.OP_ACCEPT);
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```
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### 6.3 ?????
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???????????? Selector ?? select() ??????????????????????????????????????????????????????????????????????? select() ?????????????????????????????
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??????????????? Selector ?? selectedKeys() ?????????????????????? SelectionKey ???????? ???? ??
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??????????? SelectionKeys ?????¦Ä?????? SelectionKey ??????????????????? SelectionKey????????????????????? I/O ???????????????????§» I/O ????
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```java
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int num = selector.select();
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Set selectedKeys = selector.selectedKeys();
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Iterator it = selectedKeys.iterator();
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while (it.hasNext()) {
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SelectionKey key = (SelectionKey)it.next();
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// ... deal with I/O event ...
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}
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```
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### 6.4 ??????????
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??????§Ö??????????????? ServerSocketChannel??????????????????????????????????????? SelectionKey ???? readyOps() ??????????ú€????????????????
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```java
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if ((key.readyOps() & SelectionKey.OP_ACCEPT)
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== SelectionKey.OP_ACCEPT) {
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// Accept the new connection
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// ...
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}
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```
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??????????? readOps() ??????????????????????????
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### 6.5 ???????????
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?????????????????????????????????????????????????????????????????????????????? accept() ????????????
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```java
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ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
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SocketChannel sc = ssc.accept();
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```
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??????????????? SocketChannel ??????????????????????????????????????????????????????????????????????? SocketChannel ??? Selector????????????
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```java
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sc.configureBlocking( false );
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SelectionKey newKey = sc.register( selector, SelectionKey.OP_READ );
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```
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?????????? register() ?? OP_READ ???????? SocketChannel ??????? ??? ?????? ???? ???????
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### 6.6 ?????????? SelectionKey
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????? SelectionKey ???????????????????????????????????????????????? SelectionKey ????????????????????????????????????????????????????????????????????????????????????????????¦Ä????????????????????? remove() ???????????????? SelectionKey??
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```java
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it.remove();
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```
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???????????????????????????????????§Õ????????(???????????? I/O ???)???
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### 6.7 ????? I/O
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?????????????????????????????????? I/O ??????????????????§Ö??? Selector.select()????????????????? I/O ?????????¦²? SelectionKey ???????? OP_READ ??????????????
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```java
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} else if ((key.readyOps() & SelectionKey.OP_READ)
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== SelectionKey.OP_READ) {
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// Read the data
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SocketChannel sc = (SocketChannel)key.channel();
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// ...
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}
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```
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# ?¦Ï?????
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- Eckel B, ????? , ??? , ?? . Java ?????? [M]. ??§Ö????????? , 2002.
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- [IBM: NIO ????](https://www.ibm.com/developerworks/cn/education/java/j-nio/j-nio.html)
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- [ ??????? Java I/O ????????? ](https://www.ibm.com/developerworks/cn/java/j-lo-javaio/index.html)
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- [NIO ??? IO ?????? ](http://blog.csdn.net/shimiso/article/details/24990499)
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