feat(knowledge): 图片上传接口（S3 存储，限 5MB jpg/png/webp）

server-go/internal/handler/knowledge.go

@@ -5,13 +5,14 @@ import (
 
 	"silk-server-go/internal/middleware"
 	"silk-server-go/internal/model"
+	"silk-server-go/internal/service"
 
 	"github.com/gin-gonic/gin"
 	"gorm.io/gorm"
 )
 
 // RegisterKnowledgeRoutes 注册知识库路由
-func RegisterKnowledgeRoutes(rg *gin.RouterGroup, db *gorm.DB) {
+func RegisterKnowledgeRoutes(rg *gin.RouterGroup, db *gorm.DB, s3 *service.S3Service, imageBucket string) {
 	read := middleware.RequirePermission(db, "knowledge:read")
 	write := middleware.RequirePermission(db, "knowledge:write")
 
@@ -26,6 +27,8 @@ func RegisterKnowledgeRoutes(rg *gin.RouterGroup, db *gorm.DB) {
 	rg.POST("/knowledge/articles", write, createArticle(db))
 	rg.PATCH("/knowledge/articles/:id", write, updateArticle(db))
 	rg.DELETE("/knowledge/articles/:id", write, deleteArticle(db))
+
+	registerKnowledgeImageRoute(rg, db, s3, imageBucket)
 }
 
 // listDiseases 蚕病百科列表（支持 category/keyword/enabled 过滤）

server-go/internal/handler/knowledge_image.go

@@ -0,0 +1,101 @@
+package handler
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"net/http"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"silk-server-go/internal/middleware"
+	"silk-server-go/internal/service"
+
+	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
+)
+
+// maxImageSize 知识库图片大小上限（5MB）
+const maxImageSize = 5 << 20
+
+// imageContentType 根据扩展名返回图片 Content-Type
+func imageContentType(ext string) (string, bool) {
+	switch strings.ToLower(ext) {
+	case ".jpg", ".jpeg":
+		return "image/jpeg", true
+	case ".png":
+		return "image/png", true
+	case ".webp":
+		return "image/webp", true
+	}
+	return "", false
+}
+
+// validateImageFile 校验图片文件名扩展名与大小
+func validateImageFile(filename string, size int64) error {
+	if size <= 0 || size > maxImageSize {
+		return errors.New("图片大小需在 1B~5MB 之间")
+	}
+	ext := strings.ToLower(filepath.Ext(filename))
+	if _, ok := imageContentType(ext); !ok {
+		return errors.New("仅支持 jpg/jpeg/png/webp 图片")
+	}
+	return nil
+}
+
+// buildImageKey 生成 knowledge/<日期>/<随机>.ext 的对象键
+func buildImageKey(filename string) (string, string, error) {
+	ext := strings.ToLower(filepath.Ext(filename))
+	if _, ok := imageContentType(ext); !ok {
+		return "", "", errors.New("仅支持 jpg/jpeg/png/webp 图片")
+	}
+	buf := make([]byte, 8)
+	if _, err := rand.Read(buf); err != nil {
+		return "", "", err
+	}
+	date := time.Now().Format("20060102")
+	key := fmt.Sprintf("knowledge/%s/%s%s", date, hex.EncodeToString(buf), ext)
+	return key, ext, nil
+}
+
+// uploadKnowledgeImage 上传知识库图片（multipart 字段名 file）
+func uploadKnowledgeImage(s3 *service.S3Service, bucket string) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		file, header, err := c.Request.FormFile("file")
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "请选择图片文件（字段名 file）"})
+			return
+		}
+		defer file.Close()
+
+		if err := validateImageFile(header.Filename, header.Size); err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+			return
+		}
+		key, ext, err := buildImageKey(header.Filename)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+			return
+		}
+		contentType, _ := imageContentType(ext)
+
+		if err := s3.EnsureBucket(bucket); err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "图片存储不可用: " + err.Error()})
+			return
+		}
+		if err := s3.UploadImage(bucket, key, file, contentType); err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "图片上传失败: " + err.Error()})
+			return
+		}
+
+		url := fmt.Sprintf("%s/%s/%s", s3.Endpoint(), bucket, key)
+		c.JSON(http.StatusOK, gin.H{"url": url, "name": header.Filename, "size": header.Size})
+	}
+}
+
+// uploadImageRoute 在知识库路由组中注册图片上传（由 RegisterKnowledgeRoutes 调用）
+func registerKnowledgeImageRoute(rg *gin.RouterGroup, db *gorm.DB, s3 *service.S3Service, bucket string) {
+	rg.POST("/knowledge/images", middleware.RequirePermission(db, "knowledge:write"), uploadKnowledgeImage(s3, bucket))
+}

server-go/internal/handler/knowledge_image_test.go

@@ -0,0 +1,66 @@
+package handler
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestValidateImageFileRejectsOversize(t *testing.T) {
+	if err := validateImageFile("a.png", maxImageSize+1); err == nil {
+		t.Error("超过 5MB 的图片应被拒绝")
+	}
+}
+
+func TestValidateImageFileRejectsEmptyAndBadExt(t *testing.T) {
+	if err := validateImageFile("a.png", 0); err == nil {
+		t.Error("空文件应被拒绝")
+	}
+	if err := validateImageFile("a.txt", 1024); err == nil {
+		t.Error("非图片扩展名应被拒绝")
+	}
+}
+
+func TestValidateImageFileAcceptsAllowed(t *testing.T) {
+	for _, name := range []string{"a.jpg", "a.jpeg", "a.png", "a.webp"} {
+		if err := validateImageFile(name, 1024); err != nil {
+			t.Errorf("%s 应被允许: %v", name, err)
+		}
+	}
+}
+
+func TestImageContentType(t *testing.T) {
+	cases := map[string]string{
+		".jpg":  "image/jpeg",
+		".jpeg": "image/jpeg",
+		".png":  "image/png",
+		".webp": "image/webp",
+	}
+	for ext, want := range cases {
+		got, ok := imageContentType(ext)
+		if !ok || got != want {
+			t.Errorf("imageContentType(%s) = %q, %v; want %q", ext, got, ok, want)
+		}
+	}
+	if _, ok := imageContentType(".gif"); ok {
+		t.Error(".gif 不应被支持")
+	}
+}
+
+func TestBuildImageKey(t *testing.T) {
+	key, ext, err := buildImageKey("病蚕照片.PNG")
+	if err != nil {
+		t.Fatalf("buildImageKey 失败: %v", err)
+	}
+	if !strings.HasPrefix(key, "knowledge/") {
+		t.Errorf("key 应以 knowledge/ 开头: %s", key)
+	}
+	if !strings.HasSuffix(key, ".png") {
+		t.Errorf("key 应以 .png 结尾: %s", key)
+	}
+	if ext != ".png" {
+		t.Errorf("ext = %s, want .png", ext)
+	}
+	if len(key) <= len("knowledge/")+8 {
+		t.Errorf("key 应包含日期与随机部分: %s", key)
+	}
+}