diff --git a/day09/goroutine/README.md b/day09/goroutine/README.md
new file mode 100644
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+++ b/day09/goroutine/README.md
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+# goroutine
\ No newline at end of file
diff --git a/day09/goroutine/arch.drawio b/day09/goroutine/arch.drawio
new file mode 100644
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+++ b/day09/goroutine/arch.drawio
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diff --git a/day09/tcp/README.md b/day09/tcp/README.md
new file mode 100644
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--- /dev/null
+++ b/day09/tcp/README.md
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+# TCP编程
+
diff --git a/day09/tcp/client/README.md b/day09/tcp/client/README.md
new file mode 100644
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--- /dev/null
+++ b/day09/tcp/client/README.md
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+# TCP Client
+
diff --git a/day09/tcp/client/main.go b/day09/tcp/client/main.go
new file mode 100644
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+++ b/day09/tcp/client/main.go
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+package main
+
+import (
+ "fmt"
+ "io"
+ "net"
+)
+
+func main() {
+ // 1. 连接服务器
+ conn, err := net.Dial("tcp", "localhost:8080")
+ if err != nil {
+ fmt.Println("Error connecting:", err)
+ return
+ }
+ defer conn.Close()
+ fmt.Println("Connected to server")
+
+ // 2. 发送数据
+ _, err = conn.Write([]byte("Hello, Server! I am a client."))
+ if err != nil {
+ fmt.Println("Error writing data:", err)
+ return
+ }
+ fmt.Println("Written 22 bytes:", "Hello, Server! I am a client.")
+
+ // 3. 接收数据
+ buf := make([]byte, 1024)
+ n, err := conn.Read(buf)
+ if err == io.EOF {
+ fmt.Println("Server closed connection")
+ return
+ }
+ if err != nil {
+ fmt.Println("Error reading data:", err)
+ return
+ }
+ fmt.Println("Read", len(buf), "bytes:", "Hello, Server! I have received your message: "+string(buf[:n])+"\n")
+}
diff --git a/day09/tcp/flow.drawio b/day09/tcp/flow.drawio
new file mode 100644
index 0000000..df6c1ca
--- /dev/null
+++ b/day09/tcp/flow.drawio
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diff --git a/day09/tcp/server/README.md b/day09/tcp/server/README.md
new file mode 100644
index 0000000..826880c
--- /dev/null
+++ b/day09/tcp/server/README.md
@@ -0,0 +1 @@
+# TCP Server
\ No newline at end of file
diff --git a/day09/tcp/server/main.go b/day09/tcp/server/main.go
new file mode 100644
index 0000000..b2c7657
--- /dev/null
+++ b/day09/tcp/server/main.go
@@ -0,0 +1,72 @@
+package main
+
+import (
+ "fmt"
+ "net"
+ "io"
+)
+
+func main() {
+ // 1. 监听端口
+ listener, err := net.Listen("tcp", ":8080")
+ if err != nil {
+ fmt.Println("Error listening:", err)
+ return
+ }
+ defer listener.Close()
+ fmt.Println("Server is listening on port 8080")
+
+ // 2. 接受连接
+ for {
+ conn, err := listener.Accept()
+ if err != nil {
+ fmt.Println("Error accepting connection:", err)
+ continue
+ }
+ // 3. 处理连接
+ // 使用 goroutine 并发处理连接
+ // 这样就可以同时处理多个连接，提高并发能力 (非阻塞)
+ go handleConnection(conn)
+ }
+}
+
+// 处理连接
+// 1. 读取数据
+// 2. 处理数据
+// 3. 写入数据
+func handleConnection(conn net.Conn) {
+ defer func() {
+ conn.Close()
+ fmt.Println("Connection closed by client")
+ }()
+
+ fmt.Println("New connection accepted")
+
+ // 4. 循环读取数据
+ for {
+ // 4.1 读取数据
+ buf := make([]byte, 1024)
+ n, err := conn.Read(buf)
+ // 如果客户端关闭连接，则退出循环
+ if err == io.EOF {
+ fmt.Println("Client closed connection")
+ break
+ }
+ if err != nil {
+ fmt.Println("Error reading data:", err)
+ break
+ }
+
+ // 4.3 处理数据
+ fmt.Println("Read", n, "bytes:", string(buf[:n]))
+
+
+ // 4.2 写入数据
+ _, err = conn.Write([]byte("Hello, Client! I have received your message: " + string(buf[:n]) + "\n"))
+ if err != nil {
+ fmt.Println("Error writing data:", err)
+ break
+ }
+ fmt.Println("Written", n, "bytes:", "Hello, Client! I have received your message: " + string(buf[:n]) + "\n")
+ }
+}
\ No newline at end of file