!193 跨域方法 支持重定向

Merge pull request !193 from 高雄/N/A

server/src/main/java/cn/keking/web/controller/OnlinePreviewController.java

@@ -30,8 +30,11 @@ import javax.servlet.http.HttpServletResponse;
 import java.awt.image.RenderedImage;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.UnsupportedEncodingException;
 import java.net.HttpURLConnection;
 import java.net.URL;
+import java.net.URLDecoder;
+import java.nio.charset.StandardCharsets;
 import java.text.SimpleDateFormat;
 import java.util.Arrays;
 import java.util.Date;
@@ -63,6 +66,7 @@ public class OnlinePreviewController {
 
     @GetMapping( "/onlinePreview")
     public String onlinePreview(String url, Model model, HttpServletRequest req) {
+  
         String fileUrl;
         try {
             fileUrl = WebUtils.decodeUrl(url);
@@ -121,6 +125,7 @@ public class OnlinePreviewController {
         }
         HttpURLConnection urlcon = null;
         InputStream inputStream = null;
+        String urlStr;
         assert urlPath != null;
         if (!urlPath.toLowerCase().startsWith("http") && !urlPath.toLowerCase().startsWith("https") && !urlPath.toLowerCase().startsWith("ftp")) {
             logger.info("读取跨域文件异常，可能存在非法访问，urlPath：{}", urlPath);
@@ -135,19 +140,43 @@ public class OnlinePreviewController {
                 urlcon.setReadTimeout(30000);
                 urlcon.setInstanceFollowRedirects(false);
                 int responseCode = urlcon.getResponseCode();
+                if ( responseCode == 403  || responseCode == 500) { //403  500
+                    logger.error("读取跨域文件异常，url：{}，错误：{}", urlPath,responseCode);
+                    return ;
+                }
                 if (responseCode == HttpURLConnection.HTTP_MOVED_PERM || responseCode == HttpURLConnection.HTTP_MOVED_TEMP) { //301 302
                     url =new URL(urlcon.getHeaderField("Location"));
                     urlcon=(HttpURLConnection)url.openConnection();
+                } if (responseCode  == 404 ) {  //404
+                    try {
+                        urlStr = URLDecoder.decode(urlPath, StandardCharsets.UTF_8.name());
+                        urlStr = URLDecoder.decode(urlStr, StandardCharsets.UTF_8.name());
+                        url = WebUtils.normalizedURL(urlStr);
+                        urlcon=(HttpURLConnection)url.openConnection();
+                        urlcon.setConnectTimeout(30000);
+                        urlcon.setReadTimeout(30000);
+                        urlcon.setInstanceFollowRedirects(false);
+                        responseCode = urlcon.getResponseCode();
+                        if (responseCode == HttpURLConnection.HTTP_MOVED_PERM || responseCode == HttpURLConnection.HTTP_MOVED_TEMP) { //301 302
+                            url =new URL(urlcon.getHeaderField("Location"));
+                        }
+                        if(responseCode == 404 ||responseCode  == 403  || responseCode == 500 ){
+                            logger.error("读取跨域文件异常，url：{}，错误：{}", urlPath,responseCode);
+                            return ;
+                        }
+                    } catch (UnsupportedEncodingException e) {
+                        e.printStackTrace();
+                    }finally {
+                        assert urlcon != null;
+                        urlcon.disconnect();
+                    }
                 }
-                if (responseCode  == HttpURLConnection.HTTP_NOT_FOUND  ||responseCode  == HttpURLConnection.HTTP_FORBIDDEN  || responseCode == HttpURLConnection.HTTP_INTERNAL_ERROR ) { //403 404 500
-                    logger.error("读取跨域文件异常，url：{}，错误：{}", urlPath,responseCode);
-                } else {
                     if(urlPath.contains( ".svg")) {
                         response.setContentType("image/svg+xml");
                     }
                     inputStream=(url).openStream();
                     IOUtils.copy(inputStream, response.getOutputStream());
-                }
+
             } catch (IOException | GalimatiasParseException e) {
                 logger.error("读取跨域文件异常，url：{}", urlPath);
             } finally {