add net questions

data/2.Java中阶/5.NIO/1.NIO概述/NIOAbstract.md

@@ -15,7 +15,7 @@ NIO与传统IO变化不大
 ### A
 
 ```
-NIO全称是no-blocking io
+NIO全称是no-blocking io（或者New IO）
 ```
 
 ### B

data/2.Java中阶/5.NIO/3.Channel（通道）/Channel.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "Channel.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/5.NIO/3.Channel（通道）/Channel.md

+# Channel
+
+
+以下关于 `Channel` 的说法错误的是：
+
+
+## 答案
+
+```
+DatagramChannel用于TCP数据读写
+```
+
+## 选项
+
+### A
+
+```
+通道可以异步读写
+```
+
+### B
+
+```
+通道总是基于Buffer来读写数据
+```
+
+### C
+
+```
+通道可读可写
+```

data/2.Java中阶/5.NIO/3.Channel（通道）/ChannelType.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "ChannelType.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/5.NIO/3.Channel（通道）/ChannelType.md

+# Channel Type
+
+
+以下属于 `Channel` 类型的是：
+
+
+## 答案
+
+```
+以上选项都是
+```
+
+## 选项
+
+### A
+
+```
+SctpChannel，SctpMultiChannel，SctpServerChannel
+```
+
+### B
+
+```
+DatagramChannel，FileChannel
+```
+
+### C
+
+```
+ServerSocketChannel，ServerChannel
+```

data/2.Java中阶/5.NIO/3.Channel（通道）/config.json

@@ -2,6 +2,6 @@
   "node_id": "java-1cbb9d1ea7c74caeaf8d88c2aad75965",
   "keywords": [],
   "children": [],
-  "export": [],
+  "export": ["Channel.json","ChannelType.json"],
   "title": "Channel（通道）"
 }
\ No newline at end of file

data/2.Java中阶/5.NIO/4.Java新IO概述/config.json

-{
-  "node_id": "java-f824cb48cef64bbcad371bb304b26d10",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "Java新IO概述"
-}
\ No newline at end of file

data/2.Java中阶/5.NIO/4.字符集和Charset/Charset.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "Charset.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/5.NIO/4.字符集和Charset/Charset.md

+# NIO Charset
+
+
+以下关于 `NIO Charset` 说法正确的是：
+
+## 答案
+
+```
+向ByteBuffer存放数据需要考虑字符集的编码方式
+```
+
+## 选项
+
+### A
+
+```
+向ByteBuffer存放数据不需要考虑字符集的编码方式
+```
+
+### B
+
+```
+向CharBuffer中读取时需要考虑字符集的解码
+```
+
+### C
+
+```
+Charset类在java.io.charset包中
+```

data/2.Java中阶/5.NIO/7.字符集和Charset/config.json → data/2.Java中阶/5.NIO/4.字符集和Charset/config.json

@@ -2,6 +2,6 @@
   "node_id": "java-984b508fc9a54650aa9509eeb198f925",
   "keywords": [],
   "children": [],
-  "export": [],
+  "export": ["Charset.json"],
   "title": "字符集和Charset"
 }
\ No newline at end of file

data/2.Java中阶/5.NIO/5.使用Buffer/config.json

-{
-  "node_id": "java-4bae5939bee44a31ba92906e490293b0",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "使用Buffer"
-}
\ No newline at end of file

data/2.Java中阶/5.NIO/5.文件锁/FileLock.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "FileLock.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/5.NIO/5.文件锁/FileLock.md

+# File Lock
+
+
+使用多线程读写同一个文件，选出你认为最合理的一种读取方法：
+
+
+## 答案
+
+```java
+public void readFile(String path) {
+    RandomAccessFile file = null;
+    FileLock lock = null;
+    try {
+        file = new RandomAccessFile(path, "rw");
+        FileChannel fileChannel = file.getChannel();
+        lock = fileChannel.lock();
+        // read and write 
+    } catch (IOException e) {
+        System.out.println(e);
+    } finally {
+        if (lock != null) {
+            try {
+                lock.release();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+        if (file != null) {
+            try {
+                file.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}
+```
+
+## 选项
+
+### A
+
+```java
+public void readFile(String path) throws IOException {
+    RandomAccessFile file = new RandomAccessFile(path, "rw");
+    FileChannel fileChannel = file.getChannel();
+    // read and write 
+    file.close();
+}
+```
+
+### B
+
+```java
+
+public void readFile(String path) throws IOException {
+    RandomAccessFile file = new RandomAccessFile(path, "rw");
+    FileChannel fileChannel = file.getChannel();
+    FileLock lock = fileChannel.lock();
+    // read and write 
+    lock.release();
+    file.close();
+}
+```
+
+### C
+
+```java
+public void readFile(String path) {
+    RandomAccessFile file = null;
+    FileLock lock = null;
+    try {
+        file = new RandomAccessFile(path, "rw");
+        FileChannel fileChannel = file.getChannel();
+        lock = fileChannel.lock();
+        // read and write 
+    } catch (IOException e) {
+        System.out.println(e);
+    } finally {
+        try {
+            lock.release();
+            file.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}
+```

data/2.Java中阶/5.NIO/8.文件锁/config.json → data/2.Java中阶/5.NIO/5.文件锁/config.json

@@ -2,6 +2,6 @@
   "node_id": "java-338c2cfa55b346a0a0cd4dfc61c40ae6",
   "keywords": [],
   "children": [],
-  "export": [],
+  "export": ["FileLock.json"],
   "title": "文件锁"
 }
\ No newline at end of file

data/2.Java中阶/5.NIO/6.Path接口/Path.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "Path.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/5.NIO/6.Path接口/Path.md

+# NIO Path
+
+
+以下关于 `Path` 说法错误的是：
+
+
+## 答案
+
+```
+Path是在Java 8中新增的
+```
+
+## 选项
+
+### A
+
+```
+Path表示的路径与平台无关
+```
+
+### B
+
+```
+Path可以通过Paths.get()方法创建
+```
+
+### C
+
+```
+File可以替换Path
+```
\ No newline at end of file

data/2.Java中阶/5.NIO/9.Path接口/config.json → data/2.Java中阶/5.NIO/6.Path接口/config.json

 {
   "node_id": "java-386113b4f6274eb591e1f01b39f0c8ce",
-  "keywords": [],
+  "keywords": ["Paths", "Path"],
   "children": [],
-  "export": [],
+  "export": ["Path.json"],
   "title": "Path接口"
 }
\ No newline at end of file

data/2.Java中阶/5.NIO/6.使用Channel/config.json

-{
-  "node_id": "java-9e2f3a44543c457e84d3d8a2e8321b65",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "使用Channel"
-}
\ No newline at end of file

data/2.Java中阶/5.NIO/7.Files工具类/Files.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "Files.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/5.NIO/7.Files工具类/Files.md

+# Files
+
+
+下列对于 `Files` 的相关操作方法，错误的是：
+
+
+## 答案
+
+```java
+// 复制文件，如果目的文件存在则会覆盖
+public void copyFile(String sourcePath, String destPath) throws IOException {
+    Path sp = Paths.get(sourcePath);
+    Path dp = Paths.get(destPath);
+    Files.copy(sp, dp);
+}
+```
+
+## 选项
+
+### A
+
+```java
+// 判断文件是否存在
+public Boolean isExists(String filePath) {
+    Path path = Paths.get(filePath);
+    return Files.exists(path, new LinkOption[]{ LinkOption.NOFOLLOW_LINKS});
+}
+```
+
+### B
+
+```java
+// 删除文件
+public void deleteFile(String filePath) throws IOException {
+    Path path = Paths.get(filePath);
+    Files.delete(path);
+}
+```
+
+### C
+
+```java
+// 创建文件
+public void createFile(String filePath) throws IOException {
+    Path path = Paths.get(filePath);
+    Files.createFile(path);
+}
+```

data/2.Java中阶/5.NIO/10.Files工具类/config.json → data/2.Java中阶/5.NIO/7.Files工具类/config.json

@@ -2,6 +2,6 @@
   "node_id": "java-868e1323bfdf4c239a6552a45a30d48d",
   "keywords": [],
   "children": [],
-  "export": [],
+  "export": ["Files.json"],
   "title": "Files工具类"
 }
\ No newline at end of file

data/2.Java中阶/6.网络编程/1.网络编程基础/Internet.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "Internet.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/6.网络编程/1.网络编程基础/Internet.md

+# 网络编程基础
+
+
+下列对于 `网络编程` 的相关说法正确的是：
+
+
+## 答案
+
+```
+以上说法均正确
+```
+
+## 选项
+
+### A
+
+```
+TCP/IP协议是Internet最基础最广泛的协议
+```
+
+### B
+
+```
+IP地址是网络中计算机的唯一标识
+```
+
+### C
+
+```
+UDP是无连接的，TCP是有连接的
+```

data/2.Java中阶/6.网络编程/1.网络编程基础/config.json

 {
   "node_id": "java-59e7173695814c90858bc221e8688329",
-  "keywords": [],
+  "keywords": ["网络", "通信", "协议"],
   "children": [
     {
       "网络通信协议": {
@@ -34,6 +34,6 @@
       }
     }
   ],
-  "export": [],
+  "export": ["Internet.json"],
   "title": "网络编程基础"
 }
\ No newline at end of file

data/2.Java中阶/6.网络编程/2.UDP通信/UDP.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "UDP.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/6.网络编程/2.UDP通信/UDP.md

+# UDP
+
+
+观察以下关于 `UDP` 的程序，接收端的输出为：
+```java
+// 省略import
+public class UDPSender {
+    public static void main(String[] args) throws Exception {
+        String[] messages = {"你好！", "我叫小白", "很高兴认识你"};
+        DatagramSocket ds = new DatagramSocket();
+        for (String message: messages) {
+            byte[] data = message.getBytes(StandardCharsets.UTF_8);
+            DatagramPacket dp = new DatagramPacket(data, data.length,
+                    InetAddress.getLocalHost(),8080);
+            ds.send(dp);
+            Thread.sleep(1000);
+        }
+        ds.close();
+    }
+}
+```
+```java
+// 省略import
+public class UDPReceive {
+    public static void main(String[] args)throws Exception{
+        DatagramSocket ds = new DatagramSocket(8080);
+        byte[] data = new byte[1024];
+        while (!ds.isClosed()) {
+            DatagramPacket dp = new DatagramPacket(data, data.length);
+            ds.receive(dp);
+            int len = dp.getLength();
+            System.out.println(new String(data, 0, len));
+        }
+        ds.close();
+    }
+}
+```
+
+## 答案
+
+```
+你好！
+我叫小白
+很高兴认识你
+```
+
+## 选项
+
+### A
+
+```
+￤ﾽﾠ￥ﾥﾽ￯ﾼﾁ
+￦ﾈﾑ￥ﾏﾫ￥ﾰﾏ￧ﾙﾽ
+￥ﾾﾈ￩ﾫﾘ￥ﾅﾴ￨ﾮﾤ￨ﾯﾆ￤ﾽﾠ
+```
+
+### B
+
+```
+很高兴认识你
+```
+
+### C
+
+```
+啥都不输出
+```

data/2.Java中阶/6.网络编程/2.UDP通信/config.json

@@ -41,6 +41,6 @@
       }
     }
   ],
-  "export": [],
+  "export": ["UDP.json"],
   "title": "UDP通信"
 }
\ No newline at end of file

data/2.Java中阶/6.网络编程/3.TCP通信/TCP.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "TCP.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/6.网络编程/3.TCP通信/TCP.md

+# UDP
+
+
+观察以下关于 `TCP` 的程序，服务端和客户端的输出为：
+```java
+// 省略import
+public class TCPClient {
+    public static void main(String[] args) throws Exception{
+        String[] messages = {"你好！", "我叫小白", "很高兴认识你"};
+        Socket socket = new Socket(InetAddress.getLocalHost(),8080);
+        OutputStream out = socket.getOutputStream();
+        InputStream in = socket.getInputStream();
+        for (String message: messages) {
+            out.write(message.getBytes());
+            byte[] buf = new byte[1024];
+            int len = in.read(buf);
+            System.out.println(new String(buf,0, len));
+        }
+        socket.close();
+    }
+}
+```
+```java
+// 省略import
+public class TCPServer {
+    public static void main(String[] args) throws Exception {
+        String response = "收到";
+        ServerSocket serverSocket = new ServerSocket(8080);
+        Socket socket = serverSocket.accept();
+        while (true) {
+            InputStream in = socket.getInputStream();
+            byte[] buf = new byte[1024];
+            int len = in.read(buf);
+            if (len == -1) {
+                continue;
+            }
+            System.out.println(new String(buf,0, len));
+
+            OutputStream out = socket.getOutputStream();
+            out.write(response.getBytes());
+            Thread.sleep(1000);
+        }
+    }
+}
+```
+
+## 答案
+
+```
+服务端的输出为：
+你好！
+我叫小白
+很高兴认识你
+```
+
+## 选项
+
+### A
+
+```
+客户端的输出为：
+
+```
+
+### B
+
+```
+服务端的输出为：
+￤ﾽﾠ￥ﾥﾽ￯ﾼﾁ
+￦ﾈﾑ￥ﾏﾫ￥ﾰﾏ￧ﾙﾽ
+￥ﾾﾈ￩ﾫﾘ￥ﾅﾴ￨ﾮﾤ￨ﾯﾆ￤ﾽﾠ
+```
+
+### C
+
+```
+服务端的输出为：
+很高兴认识你
+我叫小白
+你好！
+```

data/2.Java中阶/6.网络编程/3.TCP通信/config.json

@@ -48,6 +48,6 @@
       }
     }
   ],
-  "export": [],
+  "export": ["TCP.json"],
   "title": "TCP通信"
 }
\ No newline at end of file

data/2.Java中阶/6.网络编程/5.Java的基本网络支持/Support.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "Support.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/6.网络编程/5.Java的基本网络支持/Support.md

+# Java基本网络支持
+
+
+下列对于Java网络支持的相关说法错误的是：
+
+
+## 答案
+
+```
+URI是统一资源标识符，可以用来定位资源
+```
+
+## 选项
+
+### A
+
+```
+InetAddress类有两个子类：Inet4Address和Inet6Address
+```
+
+### B
+
+```
+URLDecoder和URLEncoder用于完成普通字符串和MIME字符串之间的相互转换
+```
+
+### C
+
+```
+URL是统一资源定位器
+```

data/2.Java中阶/6.网络编程/5.Java的基本网络支持/config.json

@@ -19,6 +19,6 @@
       }
     }
   ],
-  "export": [],
+  "export": ["Support.json"],
   "title": "Java的基本网络支持"
 }
\ No newline at end of file

data/2.Java中阶/6.网络编程/9.Java 11标准化的HTTP Client/HTTPClient.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "HTTPClient.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/6.网络编程/9.Java 11标准化的HTTP Client/HTTPClient.md

+# HTTPClient
+
+
+下列语句皆为使用HTTPClient获取网页的流程之一，其中不正确的是：
+
+
+## 答案
+
+```java
+HttpResponse.BodyHandler<String> bodyHandler = HttpResponse.BodyHandlers;
+```
+
+## 选项
+
+### A
+
+```java
+String url = "https://www.baidu.com";
+HttpClient client = HttpClient.newBuilder().build();
+```
+
+### B
+
+```java
+HttpRequest request = HttpRequest.newBuilder()
+                .uri(URI.create(url))
+                .header("Content-Type", "text/html")
+                .GET()
+                .build();
+```
+
+### C
+
+```java
+HttpResponse<String> response = client.send(request, bodyHandler);
+if (response.statusCode() == 200) {
+    System.out.println(response.body());
+}
+```

data/2.Java中阶/6.网络编程/9.Java 11标准化的HTTP Client/WebSocket.json

+{
+    "type": "code_options",
+    "author": "clong",
+    "source": "WebSocket.md",
+    "exercise_id": "",
+    "notebook_enable": true
+}
\ No newline at end of file

data/2.Java中阶/6.网络编程/9.Java 11标准化的HTTP Client/WebSocket.md

+# WebSocket
+
+
+`WebSocket`可以实现服务端对客户端的推送，避免客户端轮询，造成带宽资源浪费。以下关于`WebSocket`的说法错误的是：
+
+
+## 答案
+
+```
+WebSockt与HTTP都是基于TCP的，因此url也是以HTTP开头
+```
+
+## 选项
+
+### A
+
+```
+WebSocket基于TCP协议
+```
+
+### B
+
+```
+WebSocket是双向的，即全双工协议
+```
+
+### C
+
+```
+WebSocket是一种有状态的协议
+```

data/2.Java中阶/6.网络编程/9.Java 11标准化的HTTP Client/config.json

 {
   "node_id": "java-dd60957a0a7f4155a68aea7c6807d504",
-  "keywords": [],
+  "keywords": ["websocket", "get", "post", "delete", "put", "请求"],
   "children": [
     {
       "发送同步GET请求": {
@@ -41,6 +41,6 @@
       }
     }
   ],
-  "export": [],
+  "export": ["HTTPClient.json", "WebSocket.json"],
   "title": "Java 11标准化的HTTP Client"
 }
\ No newline at end of file