使client有携带上下文的能力

client.go

@@ -73,6 +73,7 @@ type Client struct {
 	responseBodyTransformer func(rawBody []byte, req *Request, resp *Response) (transformedBody []byte, err error)
 	resultStateCheckFunc    func(resp *Response) ResultState
 	onError                 ErrorHook
+	ctx                     *clientContext // 使Client拥有携带上下文信息的能力
 }
 
 type ErrorHook func(client *Client, req *Request, resp *Response, err error)
@@ -82,6 +83,7 @@ func (c *Client) R() *Request {
 	return &Request{
 		client:      c,
 		retryOption: c.retryOption.Clone(),
+		ctx:         c.Context(), // 继承 Client 的上下文
 	}
 }
 
@@ -1527,6 +1529,12 @@ func (c *Client) Clone() *Client {
 	cc.afterResponse = cloneSlice(c.afterResponse)
 	cc.dumpOptions = c.dumpOptions.Clone()
 	cc.retryOption = c.retryOption.Clone()
+
+	// clone context and clientContext
+	cc.ctx = &clientContext{
+		context: c.ctx.context,
+	}
+
 	return &cc
 }
 
@@ -1565,6 +1573,9 @@ func C() *Client {
 		xmlMarshal:            xml.Marshal,
 		xmlUnmarshal:          xml.Unmarshal,
 		cookiejarFactory:      memoryCookieJarFactory,
+		ctx: &clientContext{
+			context: context.Background(),
+		},
 	}
 	c.SetRedirectPolicy(DefaultRedirectPolicy())
 	c.initCookieJar()

context.go

@@ -0,0 +1,78 @@
+package req
+
+import (
+	"context"
+	"sync"
+)
+
+// clientContext 为 Client 提供上下文能力，确保并发安全
+type clientContext struct {
+	mu      sync.RWMutex
+	context context.Context
+}
+
+// WithContext 添加上下文键值对，使用读写锁保证并发安全
+// 这种方式避免了 Clone 整个 Client 的开销
+func (c *Client) WithContext(key, value any) *Client {
+	if c.ctx == nil {
+		c.ctx = &clientContext{
+			context: context.Background(),
+		}
+	}
+
+	c.ctx.mu.Lock()
+	defer c.ctx.mu.Unlock()
+
+	if c.ctx.context == nil {
+		c.ctx.context = context.Background()
+	}
+	c.ctx.context = context.WithValue(c.ctx.context, key, value)
+	return c
+}
+
+// GetContext 获取上下文值，使用读锁保证并发安全
+func (c *Client) GetContext(key any) any {
+	if c.ctx == nil {
+		return context.Background().Value(key)
+	}
+
+	c.ctx.mu.RLock()
+	defer c.ctx.mu.RUnlock()
+
+	if c.ctx.context == nil {
+		return nil
+	}
+	return c.ctx.context.Value(key)
+}
+
+// SetContext 设置基础上下文，使用写锁保证并发安全
+func (c *Client) SetContext(ctx context.Context) *Client {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	if c.ctx == nil {
+		c.ctx = &clientContext{}
+	}
+
+	c.ctx.mu.Lock()
+	defer c.ctx.mu.Unlock()
+
+	c.ctx.context = ctx
+	return c
+}
+
+// Context 获取当前上下文，使用读锁保证并发安全
+func (c *Client) Context() context.Context {
+	if c.ctx == nil {
+		return context.Background()
+	}
+
+	c.ctx.mu.RLock()
+	defer c.ctx.mu.RUnlock()
+
+	if c.ctx.context == nil {
+		return context.Background()
+	}
+	return c.ctx.context
+}