Move Pb Details parsing into SolidClientException

Parsing Problem Details parsing into the SolidClientExceptions makes it
possible to reuse, e.g. in the upcoming BodyHandlers changes.

Author: NSeydoux

solid/src/main/java/com/inrupt/client/solid/SolidClient.java

@@ -22,8 +22,6 @@
 
 import com.inrupt.client.*;
 import com.inrupt.client.auth.Session;
-import com.inrupt.client.spi.JsonService;
-import com.inrupt.client.spi.ServiceProvider;
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
@@ -54,21 +52,11 @@ public class SolidClient {
     private final Client client;
     private final Headers defaultHeaders;
     private final boolean fetchAfterWrite;
-    private final JsonService jsonService;
 
     SolidClient(final Client client, final Headers headers, final boolean fetchAfterWrite) {
         this.client = Objects.requireNonNull(client, "Client may not be null!");
         this.defaultHeaders = Objects.requireNonNull(headers, "Headers may not be null!");
         this.fetchAfterWrite = fetchAfterWrite;
-        JsonService js;
-        try {
-            // It is acceptable for a SolidClient instance to be in a classpath without any implementation for
-            // JsonService, in which case the ProblemDetails exceptions will fallback to default and not be parsed.
-            js = ServiceProvider.getJsonService();
-        } catch (IllegalStateException e) {
-            js = null;
-        }
-        this.jsonService = js;
     }
 
     /**
@@ -134,7 +122,7 @@ public <T extends Resource> CompletionStage<T> read(final URI identifier, final
         return client.send(request, Response.BodyHandlers.ofByteArray())
             .thenApply(response -> {
                 if (response.statusCode() >= ERROR_STATUS) {
-                    throw this.exceptionFromErrorResponse(
+                    throw SolidClientException.fromErrorResponse(
                         "Unable to read resource at " + request.uri(),
                         response.uri(),
                         response.statusCode(),
@@ -289,7 +277,7 @@ public <T extends Resource> CompletionStage<Void> delete(final T resource, final
             if (isSuccess(res.statusCode())) {
                 return null;
             } else {
-                throw this.exceptionFromErrorResponse(
+                throw SolidClientException.fromErrorResponse(
                         "Unable to delete resource",
                         resource.getIdentifier(),
                         res.statusCode(),
@@ -381,7 +369,7 @@ <T extends Resource> Function<Response<byte[]>, CompletionStage<T>> handleRespon
             final Headers headers, final String message) {
         return res -> {
             if (!isSuccess(res.statusCode())) {
-                throw this.exceptionFromErrorResponse(
+                throw SolidClientException.fromErrorResponse(
                         message,
                         resource.getIdentifier(),
                         res.statusCode(),
@@ -472,38 +460,4 @@ static Request.BodyPublisher cast(final Resource resource) {
                     " into Solid Resource", ex);
         }
     }
-
-    private SolidClientException exceptionFromErrorResponse(
-            final String message,
-            final URI uri,
-            final int code,
-            final Headers headers,
-            final byte[] body
-    ) {
-        ProblemDetails pd;
-        if (
-                this.jsonService == null
-                || (headers != null && !headers.allValues("Content-Type").contains(ProblemDetails.MIME_TYPE))) {
-            pd = new ProblemDetails(null, HttpStatus.getStatusMessage(code), null, code, null);
-            return SolidClientException.handle(message, pd, uri, headers, new String(body));
-        }
-        try {
-            // ProblemDetails doesn't have a default constructor, and we can't use JSON mapping annotations because
-            // the JSON service is an abstraction over JSON-B and Jackson, so we deserialize the JSON object in a Map
-            // and build the ProblemDetails from the Map values.
-            final Map<String, Object> pdData = this.jsonService.fromJson(
-                    new ByteArrayInputStream(body),
-                    new HashMap<String, Object>(){}.getClass().getGenericSuperclass()
-            );
-            final String title = (String) pdData.get("title");
-            final String details = (String) pdData.get("details");
-            final URI type = URI.create((String) pdData.get("type"));
-            final URI instance = URI.create((String) pdData.get("instance"));
-            final int status = (int) pdData.get("status");
-            pd = new ProblemDetails(type, title, details, status, instance);
-        } catch (IOException e) {
-            pd = new ProblemDetails( null, HttpStatus.getStatusMessage(code), null, code, null);
-        }
-        return SolidClientException.handle(message, pd, uri, headers, new String(body));
-    }
 }

solid/src/main/java/com/inrupt/client/solid/SolidClientException.java

@@ -23,8 +23,14 @@
 import com.inrupt.client.ClientHttpException;
 import com.inrupt.client.Headers;
 import com.inrupt.client.ProblemDetails;
+import com.inrupt.client.spi.JsonService;
+import com.inrupt.client.spi.ServiceProvider;
 
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
 import java.net.URI;
+import java.util.HashMap;
+import java.util.Map;
 
 /**
  * A runtime exception for use with SolidClient HTTP operations.
@@ -37,6 +43,9 @@ public class SolidClientException extends ClientHttpException {
     private final int statusCode;
     private final String body;
     private final transient Headers headers;
+    private static JsonService jsonService;
+    private static boolean jsonServiceInitialized = false;
+
 
     /**
      * Create a SolidClient exception.
@@ -107,6 +116,62 @@ public String getBody() {
         return body;
     }
 
+    /**
+     * It is acceptable for a SolidClient instance to be in a classpath without any implementation for
+     * JsonService, in which case the ProblemDetails exceptions will fallback to default and not be parsed.
+     * @return a JsonService instance, null if none is available
+     */
+    private static JsonService getJsonService() {
+        if (SolidClientException.jsonServiceInitialized) {
+            return SolidClientException.jsonService;
+        }
+        JsonService js;
+        try {
+
+            js = ServiceProvider.getJsonService();
+        } catch (IllegalStateException e) {
+            js = null;
+        }
+        SolidClientException.jsonService = js;
+        SolidClientException.jsonServiceInitialized = true;
+        return SolidClientException.jsonService;
+    }
+
+    public static SolidClientException fromErrorResponse(
+            final String message,
+            final URI uri,
+            final int code,
+            final Headers headers,
+            final byte[] body
+    ) {
+        ProblemDetails pd;
+        final JsonService jsonService = getJsonService();
+        if (
+                jsonService == null
+                        || (headers != null && !headers.allValues("Content-Type").contains(ProblemDetails.MIME_TYPE))) {
+            pd = new ProblemDetails(null, HttpStatus.getStatusMessage(code), null, code, null);
+            return SolidClientException.handle(message, pd, uri, headers, new String(body));
+        }
+        try {
+            // ProblemDetails doesn't have a default constructor, and we can't use JSON mapping annotations because
+            // the JSON service is an abstraction over JSON-B and Jackson, so we deserialize the JSON object in a Map
+            // and build the ProblemDetails from the Map values.
+            final Map<String, Object> pdData = jsonService.fromJson(
+                    new ByteArrayInputStream(body),
+                    new HashMap<String, Object>(){}.getClass().getGenericSuperclass()
+            );
+            final String title = (String) pdData.get("title");
+            final String details = (String) pdData.get("details");
+            final URI type = URI.create((String) pdData.get("type"));
+            final URI instance = URI.create((String) pdData.get("instance"));
+            final int status = (int) pdData.get("status");
+            pd = new ProblemDetails(type, title, details, status, instance);
+        } catch (IOException e) {
+            pd = new ProblemDetails( null, HttpStatus.getStatusMessage(code), null, code, null);
+        }
+        return SolidClientException.handle(message, pd, uri, headers, new String(body));
+    }
+
     /**
      *
      * @param message the resulting exception message