Kl json (#686)

* 新增：JSON 文件格式化预览功能

* 优化：优化 JSON 文件格式化预览效果

Author: klboke

server/src/main/java/cn/keking/service/impl/JsonFilePreviewImpl.java

@@ -1,9 +1,22 @@
 package cn.keking.service.impl;
 
+import cn.keking.config.ConfigConstants;
 import cn.keking.model.FileAttribute;
+import cn.keking.model.ReturnResponse;
+import cn.keking.service.FileHandlerService;
 import cn.keking.service.FilePreview;
+import cn.keking.utils.DownloadUtils;
+import cn.keking.utils.KkFileUtils;
+import org.apache.commons.codec.binary.Base64;
 import org.springframework.stereotype.Service;
 import org.springframework.ui.Model;
+import org.springframework.web.util.HtmlUtils;
+
+import java.io.*;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
 
 /**
  * @author kl (http://kailing.pub)
@@ -13,15 +26,66 @@
 @Service
 public class JsonFilePreviewImpl implements FilePreview {
 
-    private final SimTextFilePreviewImpl simTextFilePreview;
+    private final FileHandlerService fileHandlerService;
+    private final OtherFilePreviewImpl otherFilePreview;
 
-    public JsonFilePreviewImpl(SimTextFilePreviewImpl simTextFilePreview) {
-        this.simTextFilePreview = simTextFilePreview;
+    public JsonFilePreviewImpl(FileHandlerService fileHandlerService, OtherFilePreviewImpl otherFilePreview) {
+        this.fileHandlerService = fileHandlerService;
+        this.otherFilePreview = otherFilePreview;
     }
 
     @Override
     public String filePreviewHandle(String url, Model model, FileAttribute fileAttribute) {
-        simTextFilePreview.filePreviewHandle(url, model, fileAttribute);
+        String fileName = fileAttribute.getName();
+        boolean forceUpdatedCache = fileAttribute.forceUpdatedCache();
+        String filePath = fileAttribute.getOriginFilePath();
+
+        if (forceUpdatedCache || !fileHandlerService.listConvertedFiles().containsKey(fileName) || !ConfigConstants.isCacheEnabled()) {
+            ReturnResponse<String> response = DownloadUtils.downLoad(fileAttribute, fileName);
+            if (response.isFailure()) {
+                return otherFilePreview.notSupportedFile(model, fileAttribute, response.getMsg());
+            }
+            filePath = response.getContent();
+            if (ConfigConstants.isCacheEnabled()) {
+                fileHandlerService.addConvertedFile(fileName, filePath);
+            }
+            try {
+                String fileData = readJsonFile(filePath, fileName);
+                String escapedData = HtmlUtils.htmlEscape(fileData);
+                String base64Data = Base64.encodeBase64String(escapedData.getBytes(StandardCharsets.UTF_8));
+                model.addAttribute("textData", base64Data);
+            } catch (IOException e) {
+                return otherFilePreview.notSupportedFile(model, fileAttribute, e.getLocalizedMessage());
+            }
+            return JSON_FILE_PREVIEW_PAGE;
+        }
+
+        String fileData = null;
+        try {
+            fileData = HtmlUtils.htmlEscape(readJsonFile(filePath, fileName));
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        String base64Data = Base64.encodeBase64String(fileData.getBytes(StandardCharsets.UTF_8));
+        model.addAttribute("textData", base64Data);
         return JSON_FILE_PREVIEW_PAGE;
     }
+
+    /**
+     * 读取 JSON 文件，强制使用 UTF-8 编码
+     * JSON 标准规定必须使用 UTF-8 编码
+     */
+    private String readJsonFile(String filePath, String fileName) throws IOException {
+        File file = new File(filePath);
+        if (KkFileUtils.isIllegalFileName(fileName)) {
+            return null;
+        }
+        if (!file.exists() || file.length() == 0) {
+            return "";
+        }
+
+        // JSON 标准规定使用 UTF-8 编码，不依赖自动检测
+        byte[] bytes = Files.readAllBytes(Paths.get(filePath));
+        return new String(bytes, StandardCharsets.UTF_8);
+    }
 }

server/src/main/java/cn/keking/service/impl/SimTextFilePreviewImpl.java

@@ -47,7 +47,7 @@ public String filePreviewHandle(String url, Model model, FileAttribute fileAttri
             }
             try {
                 String  fileData = HtmlUtils.htmlEscape(textData(filePath,fileName));
-                model.addAttribute("textData", Base64.encodeBase64String(fileData.getBytes()));
+                model.addAttribute("textData", Base64.encodeBase64String(fileData.getBytes(StandardCharsets.UTF_8)));
             } catch (IOException e) {
                 return otherFilePreview.notSupportedFile(model, fileAttribute, e.getLocalizedMessage());
             }
@@ -59,7 +59,7 @@ public String filePreviewHandle(String url, Model model, FileAttribute fileAttri
         } catch (IOException e) {
             e.printStackTrace();
         }
-        model.addAttribute("textData", Base64.encodeBase64String(fileData.getBytes()));
+        model.addAttribute("textData", Base64.encodeBase64String(fileData.getBytes(StandardCharsets.UTF_8)));
         return TXT_FILE_PREVIEW_PAGE;
     }