Optimize use of Jackson ObjectMapper instances

Closes gh-1789

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/context/properties/ConfigurationPropertiesReportEndpoint.java

@@ -79,6 +79,8 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 
 	private ApplicationContext context;
 
+	private ObjectMapper objectMapper;
+
 	@Override
 	public void setApplicationContext(ApplicationContext context) throws BeansException {
 		this.context = context;
@@ -94,13 +96,11 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 	}
 
 	private ApplicationConfigurationProperties extract(ApplicationContext context) {
-		ObjectMapper mapper = new ObjectMapper();
-		configureObjectMapper(mapper);
 		Map<String, ContextConfigurationProperties> contextProperties = new HashMap<>();
 		ApplicationContext target = context;
 		while (target != null) {
 			contextProperties.put(target.getId(),
-					describeConfigurationProperties(target, mapper));
+					describeConfigurationProperties(target, getObjectMapper()));
 			target = target.getParent();
 		}
 		return new ApplicationConfigurationProperties(contextProperties);
@@ -179,6 +179,14 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 		applySerializationModifier(mapper);
 	}
 
+	private ObjectMapper getObjectMapper() {
+		if (this.objectMapper == null) {
+			this.objectMapper = new ObjectMapper();
+			configureObjectMapper(this.objectMapper);
+		}
+		return this.objectMapper;
+	}
+
 	/**
 	 * Ensure only bindable and non-cyclic bean properties are reported.
 	 * @param mapper the object mapper

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/JacksonJsonParser.java

@@ -36,6 +36,20 @@ public class JacksonJsonParser extends AbstractJsonParser {
 
 	private ObjectMapper objectMapper; // Late binding
 
+	/**
+	 * Creates a instance with the specified {@link ObjectMapper}.
+	 * @param objectMapper the object mapper to use
+	 */
+	public JacksonJsonParser(ObjectMapper objectMapper) {
+		this.objectMapper = objectMapper;
+	}
+
+	/**
+	 * Creates an instance with a default {@link ObjectMapper} that is created lazily.
+	 */
+	public JacksonJsonParser() {
+	}
+
 	@Override
 	public Map<String, Object> parseMap(String json) {
 		return tryParse(() -> getObjectMapper().readValue(json, MAP_TYPE),

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/json/JacksonJsonParserTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,10 +16,22 @@
 
 package org.springframework.boot.json;
 
+import java.io.IOException;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Test;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+
 /**
  * Tests for {@link JacksonJsonParser}.
  *
  * @author Dave Syer
+ * @author Stephane Nicoll
  */
 public class JacksonJsonParserTests extends AbstractJsonParserTests {
 
@@ -28,4 +40,11 @@ public class JacksonJsonParserTests extends AbstractJsonParserTests {
 		return new JacksonJsonParser();
 	}
 
+	@Test
+	public void instanceWithSpecificObjectMapper() throws IOException {
+		ObjectMapper objectMapper = spy(new ObjectMapper());
+		new JacksonJsonParser(objectMapper).parseMap("{}");
+		verify(objectMapper).readValue(eq("{}"), any(TypeReference.class));
+	}
+
 }