Add Problem object for JSON problem documents

Backport of commit 4e1d173c, fdc05ba7

acme4j-client/src/main/java/org/shredzone/acme4j/Problem.java

@@ -0,0 +1,70 @@
+/*
+ * acme4j - Java ACME client
+ *
+ * Copyright (C) 2017 Richard "Shred" Körber
+ *   http://acme4j.shredzone.org
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+package org.shredzone.acme4j;
+
+import java.io.Serializable;
+import java.net.URI;
+
+import org.shredzone.acme4j.util.JSON;
+
+/**
+ * Represents a JSON Problem.
+ *
+ * @see <a href="https://tools.ietf.org/html/rfc7807">RFC 7807</a>
+ */
+public class Problem implements Serializable {
+    private static final long serialVersionUID = -8418248862966754214L;
+
+    private final JSON problemJson;
+
+    /**
+     * Creates a new {@link Problem} object.
+     *
+     * @param problem
+     *            Problem as JSON structure
+     */
+    public Problem(JSON problem) {
+        this.problemJson = problem;
+    }
+
+    /**
+     * Returns the problem type.
+     */
+    public URI getType() {
+        return problemJson.get("type").asURI();
+    }
+
+    /**
+     * Returns a human-readable description of the problem.
+     */
+    public String getDetail() {
+        return problemJson.get("detail").asString();
+    }
+
+    /**
+     * Returns the problem as {@link JSON} object, to access other fields.
+     */
+    public JSON asJSON() {
+        return problemJson;
+    }
+
+    /**
+     * Returns the problem as JSON string.
+     */
+    @Override
+    public String toString() {
+        return problemJson.toString();
+    }
+
+}

acme4j-client/src/main/java/org/shredzone/acme4j/util/JSON.java

@@ -41,6 +41,7 @@ import java.util.stream.StreamSupport;
 
 import org.jose4j.json.JsonUtil;
 import org.jose4j.lang.JoseException;
+import org.shredzone.acme4j.Problem;
 import org.shredzone.acme4j.exception.AcmeProtocolException;
 
 /**
@@ -294,6 +295,19 @@ public final class JSON implements Serializable {
             }
         }
 
+        /**
+         * Returns the value as {@link Problem}.
+         *
+         * @return {@link Problem}, or {@code null} if the value was not set.
+         */
+        public Problem asProblem() {
+            if (val == null) {
+                return null;
+            }
+
+            return new Problem(asObject());
+        }
+
         /**
          * Returns the value as JSON array.
          *

acme4j-client/src/test/java/org/shredzone/acme4j/ProblemTest.java

@@ -0,0 +1,43 @@
+/*
+ * acme4j - Java ACME client
+ *
+ * Copyright (C) 2017 Richard "Shred" Körber
+ *   http://acme4j.shredzone.org
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+package org.shredzone.acme4j;
+
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+import static uk.co.datumedge.hamcrest.json.SameJSONAs.sameJSONAs;
+
+import java.net.URI;
+
+import org.junit.Test;
+import org.shredzone.acme4j.util.JSON;
+import org.shredzone.acme4j.util.TestUtils;
+
+/**
+ * Unit tests for {@link Problem}.
+ */
+public class ProblemTest {
+
+    @Test
+    public void testProblem() {
+        JSON original = TestUtils.getJsonAsObject("problem");
+
+        Problem problem = new Problem(original);
+
+        assertThat(problem.getType(), is(URI.create("urn:ietf:params:acme:error:connection")));
+        assertThat(problem.getDetail(), is("connection refused"));
+        assertThat(problem.asJSON().toString(), is(sameJSONAs(original.toString())));
+        assertThat(problem.toString(), is(sameJSONAs(original.toString())));
+    }
+
+}

acme4j-client/src/test/java/org/shredzone/acme4j/util/JSONTest.java

@@ -36,6 +36,7 @@ import java.util.NoSuchElementException;
 import java.util.stream.Collectors;
 
 import org.junit.Test;
+import org.shredzone.acme4j.Problem;
 import org.shredzone.acme4j.exception.AcmeProtocolException;
 
 /**
@@ -84,7 +85,7 @@ public class JSONTest {
         JSON json = TestUtils.getJsonAsObject("json");
 
         assertThat(json.keySet(), containsInAnyOrder(
-                    "text", "number", "uri", "url", "date", "array", "collect"));
+                    "text", "number", "uri", "url", "date", "array", "collect", "problem"));
         assertThat(json.contains("text"), is(true));
         assertThat(json.contains("music"), is(false));
         assertThat(json.get("text"), is(notNullValue()));
@@ -189,6 +190,11 @@ public class JSONTest {
 
         JSON sub = array.get(3).asObject();
         assertThat(sub.get("test").asString(), is("ok"));
+
+        Problem problem = json.get("problem").asProblem();
+        assertThat(problem, is(notNullValue()));
+        assertThat(problem.getType(), is(URI.create("urn:ietf:params:acme:error:rateLimited")));
+        assertThat(problem.getDetail(), is("too many requests"));
     }
 
     /**
@@ -205,6 +211,7 @@ public class JSONTest {
         assertThat(json.get("none").asInstant(), is(nullValue()));
         assertThat(json.get("none").asArray(), is(nullValue()));
         assertThat(json.get("none").asObject(), is(nullValue()));
+        assertThat(json.get("none").asProblem(), is(nullValue()));
 
         try {
             json.get("none").asInt();
@@ -272,6 +279,13 @@ public class JSONTest {
         } catch (AcmeProtocolException ex) {
             // expected
         }
+
+        try {
+            json.get("text").asProblem();
+            fail("no exception was thrown");
+        } catch (AcmeProtocolException ex) {
+            // expected
+        }
     }
 
     /**

acme4j-client/src/test/resources/json.properties

@@ -42,7 +42,14 @@ json = \
     "url": "http://example.com",\
     "date": "2016-01-08T00:00:00Z",\
     "array": ["foo", 987, [1, 2, 3], {"test": "ok"}],\
-    "collect": ["foo", "bar", "barfoo"]\
+    "collect": ["foo", "bar", "barfoo"],\
+    "problem": {"type": "urn:ietf:params:acme:error:rateLimited", "detail": "too many requests"}\
+  }
+
+problem = \
+  {\
+    "type": "urn:ietf:params:acme:error:connection",\
+    "detail": "connection refused"\
   }
 
 newRegistration = \