perf: improve more friendly exception messages (#113)

```release-note
友好地提示异常信息
```
fixes https://github.com/halo-dev/plugin-s3/issues/105

验证方法：
1. ak/sk乱输，发生接收到403状态码（接收错误状态码）
2. endpoint网址改成不存在的，如.com改成.comaaa（未知主机）
3. endpoint端口改成没监听的（超时）

src/main/java/run/halo/s3os/S3ExceptionHandler.java

@@ -0,0 +1,42 @@
+package run.halo.s3os;
+
+import lombok.experimental.UtilityClass;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.web.server.ServerWebInputException;
+import software.amazon.awssdk.core.exception.SdkException;
+import software.amazon.awssdk.services.s3.model.S3Exception;
+
+@Slf4j
+@UtilityClass
+public class S3ExceptionHandler {
+
+    /**
+     * Map user configuration caused S3 exception to ServerWebInputException
+     * @param throwable Exception
+     * @return ServerWebInputException or original exception
+     */
+    public static Throwable map(Throwable throwable) {
+        if (throwable instanceof S3Exception s3e) {
+            log.error("S3Exception occurred", s3e);
+            return new ServerWebInputException(String.format(
+                "The object storage service returned an error status code %d. Please check the storage "
+                    + "policy configuration and make sure your account and service are working properly.",
+                s3e.statusCode()));
+        }
+        if (throwable instanceof SdkException sdke && sdke.getMessage() != null
+            && sdke.getMessage().contains("UnknownHostException")) {
+            log.error("UnknownHostException occurred", sdke);
+            return new ServerWebInputException(
+                "Received an UnknownHostException, please check if the endpoint is entered correctly, "
+                    + "especially for any spaces before or after the endpoint.");
+        }
+        if (throwable instanceof SdkException sdke && sdke.getMessage() != null
+            && sdke.getMessage().contains("Connect timed out")) {
+            log.error("ConnectTimeoutException occurred", sdke);
+            return new ServerWebInputException(
+                "Received a ConnectTimeoutException, please check if the endpoint is entered correctly, "
+                    + "and make sure your object storage service is working properly.");
+        }
+        return throwable;
+    }
+}

src/main/java/run/halo/s3os/S3LinkServiceImpl.java

@@ -1,5 +1,13 @@
 package run.halo.s3os;
 
+import static run.halo.s3os.S3OsAttachmentHandler.OBJECT_KEY;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.lang3.StringUtils;
@@ -9,38 +17,18 @@ import org.springframework.security.core.context.ReactiveSecurityContextHolder;
 import org.springframework.security.core.context.SecurityContext;
 import org.springframework.stereotype.Service;
 import org.springframework.web.server.ResponseStatusException;
-import org.springframework.web.util.UriUtils;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.core.scheduler.Schedulers;
 import run.halo.app.core.extension.attachment.Attachment;
-import run.halo.app.core.extension.attachment.Constant;
 import run.halo.app.core.extension.attachment.Policy;
 import run.halo.app.extension.ConfigMap;
-import run.halo.app.extension.Metadata;
 import run.halo.app.extension.ReactiveExtensionClient;
-import run.halo.app.infra.utils.JsonUtils;
-import software.amazon.awssdk.auth.credentials.AwsBasicCredentials;
-import software.amazon.awssdk.regions.Region;
 import software.amazon.awssdk.services.s3.S3Client;
-import software.amazon.awssdk.services.s3.S3Configuration;
 import software.amazon.awssdk.services.s3.model.HeadObjectRequest;
 import software.amazon.awssdk.services.s3.model.ListObjectsV2Request;
 import software.amazon.awssdk.services.s3.model.S3Object;
 
-import java.net.URI;
-import java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Map;
-import java.util.UUID;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicReference;
-import java.util.function.Function;
-import java.util.stream.Collectors;
-
-import static run.halo.s3os.S3OsAttachmentHandler.OBJECT_KEY;
-
 
 @Service
 @RequiredArgsConstructor
@@ -103,7 +91,8 @@ public class S3LinkServiceImpl implements S3LinkService {
                                 listObjectsV2Response.nextContinuationToken(),
                                 listObjectsV2Response.isTruncated()));
                     });
-            });
+            })
+            .onErrorMap(S3ExceptionHandler::map);
     }
 
     @Override
@@ -155,7 +144,8 @@ public class S3LinkServiceImpl implements S3LinkService {
                             .getKey() : null, tokenState.currToken,
                         limitedObjects.size() == pageSize);
                 });
-        });
+        })
+        .onErrorMap(S3ExceptionHandler::map);
     }
 
     record TokenState(String currToken, String nextToken) {
@@ -200,6 +190,7 @@ public class S3LinkServiceImpl implements S3LinkService {
                     .flatMap(client::create)
                     .thenReturn(new LinkResult.LinkResultItem(objectKey, true, null));
             }))
+            .onErrorMap(S3ExceptionHandler::map)
             .onErrorResume(throwable ->
                 Mono.just(new LinkResult.LinkResultItem(objectKey, false, throwable.getMessage())));
     }

src/main/java/run/halo/s3os/S3OsAttachmentHandler.java

@@ -82,7 +82,8 @@ public class S3OsAttachmentHandler implements AttachmentHandler {
                 final var properties = getProperties(context.configMap());
                 return upload(context, properties)
                     .subscribeOn(Schedulers.boundedElastic())
-                    .map(objectDetail -> this.buildAttachment(properties, objectDetail));
+                    .map(objectDetail -> this.buildAttachment(properties, objectDetail))
+                    .onErrorMap(S3ExceptionHandler::map);
             });
     }
 
@@ -116,6 +117,7 @@ public class S3OsAttachmentHandler implements AttachmentHandler {
                     })
                     .thenReturn(context);
             })
+            .onErrorMap(S3ExceptionHandler::map)
             .map(DeleteContext::attachment);
     }
 
@@ -152,7 +154,8 @@ public class S3OsAttachmentHandler implements AttachmentHandler {
                     }
                 },
                 SdkPresigner::close)
-            .subscribeOn(Schedulers.boundedElastic());
+            .subscribeOn(Schedulers.boundedElastic())
+            .onErrorMap(S3ExceptionHandler::map);
     }
 
     @Override

src/main/java/run/halo/s3os/S3UnlinkServiceImpl.java

@@ -1,6 +1,5 @@
 package run.halo.s3os;
 
-import java.time.Instant;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.stereotype.Service;