Polish GSON customization support

Closes gh-11498

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/gson/GsonAutoConfiguration.java

 /*
- * Copyright 2012-2014 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.
@@ -18,18 +18,16 @@ package org.springframework.boot.autoconfigure.gson;
 
 import java.util.List;
 
-import com.google.gson.FieldNamingPolicy;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
-import com.google.gson.LongSerializationPolicy;
 
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.context.properties.PropertyMapper;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.context.annotation.Primary;
 import org.springframework.core.Ordered;
 
 /**
@@ -41,120 +39,65 @@ import org.springframework.core.Ordered;
  */
 @Configuration
 @ConditionalOnClass(Gson.class)
+@EnableConfigurationProperties(GsonProperties.class)
 public class GsonAutoConfiguration {
 
-	@Configuration
-	static class GsonConfiguration {
-
-		@Bean
-		@Primary
-		@ConditionalOnMissingBean(Gson.class)
-		public Gson gson(GsonBuilder gsonBuilder) {
-			return gsonBuilder.create();
-		}
+	@Bean
+	public GsonBuilder gsonBuilder(List<GsonBuilderCustomizer> customizers) {
+		GsonBuilder builder = new GsonBuilder();
+		customizers.forEach(c -> c.customize(builder));
+		return builder;
 	}
 
-	@Configuration
-	static class GsonBuilderConfiguration {
-
-		@Bean
-		public GsonBuilder gsonBuilder(List<GsonBuilderCustomizer> customizers) {
-			final GsonBuilder gsonBuilder = new GsonBuilder();
-			customizers.forEach(c -> c.customize(gsonBuilder));
-			return gsonBuilder;
-		}
-
+	@Bean
+	@ConditionalOnMissingBean(Gson.class)
+	public Gson gson(GsonBuilder gsonBuilder) {
+		return gsonBuilder.create();
 	}
 
-	@Configuration
-	@EnableConfigurationProperties(GsonProperties.class)
-	static class GsonBuilderCustomizerConfiguration {
-
-		@Bean
-		public StandardGsonBuilderCustomizer standardGsonBuilderCustomizer(
-				GsonProperties gsonProperties) {
-			return new StandardGsonBuilderCustomizer(gsonProperties);
-		}
-
-		private static final class StandardGsonBuilderCustomizer
-				implements GsonBuilderCustomizer, Ordered {
-
-			private final GsonProperties properties;
-
-			StandardGsonBuilderCustomizer(GsonProperties properties) {
-				this.properties = properties;
-			}
-
-			@Override
-			public int getOrder() {
-				return 0;
-			}
-
-			@Override
-			public void customize(GsonBuilder gsonBuilder) {
-
-				boolean generateNonExecutableJson = this.properties
-						.isGenerateNonExecutableJson();
-				if (generateNonExecutableJson) {
-					gsonBuilder.generateNonExecutableJson();
-				}
-
-				boolean excludeFieldsWithoutExposeAnnotation = this.properties
-						.isExcludeFieldsWithoutExposeAnnotation();
-				if (excludeFieldsWithoutExposeAnnotation) {
-					gsonBuilder.excludeFieldsWithoutExposeAnnotation();
-				}
-
-				boolean serializeNulls = this.properties.isSerializeNulls();
-				if (serializeNulls) {
-					gsonBuilder.serializeNulls();
-				}
-
-				boolean enableComplexMapKeySerialization = this.properties
-						.isEnableComplexMapKeySerialization();
-				if (enableComplexMapKeySerialization) {
-					gsonBuilder.enableComplexMapKeySerialization();
-				}
-
-				boolean disableInnerClassSerialization = this.properties
-						.isDisableInnerClassSerialization();
-				if (disableInnerClassSerialization) {
-					gsonBuilder.disableInnerClassSerialization();
-				}
-
-				LongSerializationPolicy longSerializationPolicy = this.properties
-						.getLongSerializationPolicy();
-				if (longSerializationPolicy != null) {
-					gsonBuilder.setLongSerializationPolicy(longSerializationPolicy);
-				}
+	@Bean
+	public StandardGsonBuilderCustomizer standardGsonBuilderCustomizer(
+			GsonProperties gsonProperties) {
+		return new StandardGsonBuilderCustomizer(gsonProperties);
+	}
 
-				FieldNamingPolicy fieldNamingPolicy = this.properties
-						.getFieldNamingPolicy();
-				if (fieldNamingPolicy != null) {
-					gsonBuilder.setFieldNamingPolicy(fieldNamingPolicy);
-				}
+	private static final class StandardGsonBuilderCustomizer
+			implements GsonBuilderCustomizer, Ordered {
 
-				boolean prettyPrinting = this.properties.isPrettyPrinting();
-				if (prettyPrinting) {
-					gsonBuilder.setPrettyPrinting();
-				}
+		private final GsonProperties properties;
 
-				boolean isLenient = this.properties.isLenient();
-				if (isLenient) {
-					gsonBuilder.setLenient();
-				}
+		StandardGsonBuilderCustomizer(GsonProperties properties) {
+			this.properties = properties;
+		}
 
-				boolean disableHtmlEscaping = this.properties.isDisableHtmlEscaping();
-				if (disableHtmlEscaping) {
-					gsonBuilder.disableHtmlEscaping();
-				}
+		@Override
+		public int getOrder() {
+			return 0;
+		}
 
-				String dateFormat = this.properties.getDateFormat();
-				if (dateFormat != null) {
-					gsonBuilder.setDateFormat(dateFormat);
-				}
-			}
+		@Override
+		public void customize(GsonBuilder builder) {
+			GsonProperties properties = this.properties;
+			PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
+			map.from(properties::getGenerateNonExecutableJson)
+					.toCall(builder::generateNonExecutableJson);
+			map.from(properties::getExcludeFieldsWithoutExposeAnnotation)
+					.toCall(builder::excludeFieldsWithoutExposeAnnotation);
+			map.from(properties::getSerializeNulls).toCall(builder::serializeNulls);
+			map.from(properties::getEnableComplexMapKeySerialization)
+					.toCall(builder::enableComplexMapKeySerialization);
+			map.from(properties::getDisableInnerClassSerialization)
+					.toCall(builder::disableInnerClassSerialization);
+			map.from(properties::getLongSerializationPolicy)
+					.to(builder::setLongSerializationPolicy);
+			map.from(properties::getFieldNamingPolicy).to(builder::setFieldNamingPolicy);
+			map.from(properties::getPrettyPrinting).toCall(builder::setPrettyPrinting);
+			map.from(properties::getLenient).toCall(builder::setLenient);
+			map.from(properties::getDisableHtmlEscaping)
+					.toCall(builder::disableHtmlEscaping);
+			map.from(properties::getDateFormat).to(builder::setDateFormat);
 		}
+
 	}
 
 }

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/gson/GsonBuilderCustomizer.java

 /*
- * 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.

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/gson/GsonProperties.java

 /*
- * 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.
@@ -19,7 +19,6 @@ package org.springframework.boot.autoconfigure.gson;
 import com.google.gson.FieldNamingPolicy;
 import com.google.gson.Gson;
 import com.google.gson.LongSerializationPolicy;
-import com.google.gson.annotations.Expose;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
@@ -33,109 +32,103 @@ import org.springframework.boot.context.properties.ConfigurationProperties;
 public class GsonProperties {
 
 	/**
-	 * Makes the output JSON non-executable in Javascript by prefixing the generated JSON
-	 * with some special text.
+	 * Whether to generate non executable JSON by prefixing the output with some special
+	 * text.
 	 */
-	private boolean generateNonExecutableJson;
+	private Boolean generateNonExecutableJson;
 
 	/**
-	 * Configures {@link Gson} to exclude all fields from consideration for serialization
-	 * or deserialization that do not have the {@link Expose} annotation.
+	 * Whether to exclude all fields from consideration for serialization or
+	 * deserialization that do not have the "Expose" annotation.
 	 */
-	private boolean excludeFieldsWithoutExposeAnnotation;
+	private Boolean excludeFieldsWithoutExposeAnnotation;
 
 	/**
-	 * Configure {@link Gson} to serialize null fields.
+	 * Whether to to serialize null fields.
 	 */
-	private boolean serializeNulls;
+	private Boolean serializeNulls;
 
 	/**
-	 * Enabling this feature will only change the serialized form if the map key is a
-	 * complex type (i.e. non-primitive) in its serialized JSON form
+	 * Whether to enabled serialization of complex map keys (i.e. non-primitives).
 	 */
-	private boolean enableComplexMapKeySerialization;
+	private Boolean enableComplexMapKeySerialization;
 
 	/**
-	 * Configures {@link Gson} to exclude inner classes during serialization.
+	 * Whether to exclude inner classes during serialization.
 	 */
-	private boolean disableInnerClassSerialization;
+	private Boolean disableInnerClassSerialization;
 
 	/**
-	 * Configures {@link Gson} to apply a specific serialization policy for Long and long
-	 * objects.
+	 * Serialization policy for Long and long types.
 	 */
 	private LongSerializationPolicy longSerializationPolicy;
 
 	/**
-	 * Configures {@link Gson} to apply a specific naming policy to an object's field
-	 * during serialization and deserialization.
+	 * The naming policy that should be applied to an object's field during serialization
+	 * and deserialization.
 	 */
 	private FieldNamingPolicy fieldNamingPolicy;
 
 	/**
-	 * Configures {@link Gson} to output Json that fits in a page for pretty printing.
-	 * This option only affects Json serialization.
+	 * Whether to output serialized JSON that fits in a page for pretty printing.
 	 */
-	private boolean prettyPrinting;
+	private Boolean prettyPrinting;
 
 	/**
-	 * By default, {@link Gson} is strict and only accepts JSON as specified by RFC 4627.
-	 * This option makes the parser liberal in what it accepts.
+	 * Whether to be lenient about parsing JSON that doesn't conform to RFC 4627.
 	 */
-	private boolean lenient;
+	private Boolean lenient;
 
 	/**
-	 * By default, {@link Gson} escapes HTML characters such as < > etc. Use this option
-	 * to configure Gson to pass-through HTML characters as is.
+	 * Whether to disable the escaping of HTML characters such as '<' '>' etc.
 	 */
-	private boolean disableHtmlEscaping;
+	private Boolean disableHtmlEscaping;
 
 	/**
-	 * Configures {@link Gson} to serialize Date objects according to the pattern
-	 * provided.
+	 * The format to use when serializing Date objects.
 	 */
 	private String dateFormat;
 
-	public boolean isGenerateNonExecutableJson() {
+	public Boolean getGenerateNonExecutableJson() {
 		return this.generateNonExecutableJson;
 	}
 
-	public void setGenerateNonExecutableJson(boolean generateNonExecutableJson) {
+	public void setGenerateNonExecutableJson(Boolean generateNonExecutableJson) {
 		this.generateNonExecutableJson = generateNonExecutableJson;
 	}
 
-	public boolean isExcludeFieldsWithoutExposeAnnotation() {
+	public Boolean getExcludeFieldsWithoutExposeAnnotation() {
 		return this.excludeFieldsWithoutExposeAnnotation;
 	}
 
 	public void setExcludeFieldsWithoutExposeAnnotation(
-			boolean excludeFieldsWithoutExposeAnnotation) {
+			Boolean excludeFieldsWithoutExposeAnnotation) {
 		this.excludeFieldsWithoutExposeAnnotation = excludeFieldsWithoutExposeAnnotation;
 	}
 
-	public boolean isSerializeNulls() {
+	public Boolean getSerializeNulls() {
 		return this.serializeNulls;
 	}
 
-	public void setSerializeNulls(boolean serializeNulls) {
+	public void setSerializeNulls(Boolean serializeNulls) {
 		this.serializeNulls = serializeNulls;
 	}
 
-	public boolean isEnableComplexMapKeySerialization() {
+	public Boolean getEnableComplexMapKeySerialization() {
 		return this.enableComplexMapKeySerialization;
 	}
 
 	public void setEnableComplexMapKeySerialization(
-			boolean enableComplexMapKeySerialization) {
+			Boolean enableComplexMapKeySerialization) {
 		this.enableComplexMapKeySerialization = enableComplexMapKeySerialization;
 	}
 
-	public boolean isDisableInnerClassSerialization() {
+	public Boolean getDisableInnerClassSerialization() {
 		return this.disableInnerClassSerialization;
 	}
 
 	public void setDisableInnerClassSerialization(
-			boolean disableInnerClassSerialization) {
+			Boolean disableInnerClassSerialization) {
 		this.disableInnerClassSerialization = disableInnerClassSerialization;
 	}
 
@@ -156,27 +149,27 @@ public class GsonProperties {
 		this.fieldNamingPolicy = fieldNamingPolicy;
 	}
 
-	public boolean isPrettyPrinting() {
+	public Boolean getPrettyPrinting() {
 		return this.prettyPrinting;
 	}
 
-	public void setPrettyPrinting(boolean prettyPrinting) {
+	public void setPrettyPrinting(Boolean prettyPrinting) {
 		this.prettyPrinting = prettyPrinting;
 	}
 
-	public boolean isLenient() {
+	public Boolean getLenient() {
 		return this.lenient;
 	}
 
-	public void setLenient(boolean lenient) {
+	public void setLenient(Boolean lenient) {
 		this.lenient = lenient;
 	}
 
-	public boolean isDisableHtmlEscaping() {
+	public Boolean getDisableHtmlEscaping() {
 		return this.disableHtmlEscaping;
 	}
 
-	public void setDisableHtmlEscaping(boolean disableHtmlEscaping) {
+	public void setDisableHtmlEscaping(Boolean disableHtmlEscaping) {
 		this.disableHtmlEscaping = disableHtmlEscaping;
 	}
 
@@ -187,4 +180,5 @@ public class GsonProperties {
 	public void setDateFormat(String dateFormat) {
 		this.dateFormat = dateFormat;
 	}
+
 }

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/gson/GsonAutoConfigurationTests.java

 /*
- * Copyright 2012-2016 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.
@@ -34,6 +34,7 @@ import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 
 import static org.assertj.core.api.Assertions.assertThat;
+
 /**
  * Tests for {@link GsonAutoConfiguration}.
  *
@@ -246,7 +247,6 @@ public class GsonAutoConfigurationTests {
 
 	public class DataObject {
 
-		@SuppressWarnings("unused")
 		public static final String STATIC_DATA = "bye";
 
 		@SuppressWarnings("unused")
@@ -255,14 +255,16 @@ public class GsonAutoConfigurationTests {
 		public void setData(Long data) {
 			this.data = data;
 		}
+
 	}
 
 	public class WrapperObject {
 
 		@SuppressWarnings("unused")
 		class NestedObject {
-			@SuppressWarnings("unused")
+
 			private String data = "nested";
+
 		}
 	}
 

spring-boot-project/spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -340,18 +340,18 @@ content into your application. Rather, pick only the properties that you need.
 	spring.jackson.serialization.*= # Jackson on/off features that affect the way Java objects are serialized.
 	spring.jackson.time-zone= #  Time zone used when formatting dates. For instance, "America/Los_Angeles" or "GMT+10".
 
-    # GSON ({sc-spring-boot-autoconfigure}/gson/GsonProperties.{sc-ext}[GsonProperties])
-    spring.gson.date-format= # Configures Gson to serialize Date objects according to the pattern provided.
-    spring.gson.disable-html-escaping=false # By default, Gson escapes HTML characters such as < > etc. Use this option to configure Gson to pass-through HTML characters as is.
-    spring.gson.disable-inner-class-serialization=false # Configures Gson to exclude inner classes during serialization.
-    spring.gson.enable-complex-map-key-serialization=false # Enabling this feature will only change the serialized form if the map key is a complex type (i.e. non-primitive) in its serialized JSON form
-    spring.gson.exclude-fields-without-expose-annotation=false # Configures Gson to exclude all fields from consideration for serialization or deserialization that do not have the Expose  annotation.
-    spring.gson.field-naming-policy= # Configures Gson to apply a specific naming policy to an object's field during serialization and deserialization.
-    spring.gson.generate-non-executable-json=false # Makes the output JSON non-executable in Javascript by prefixing the generated JSON with some special text.
-    spring.gson.lenient=false # By default, Gson is strict and only accepts JSON as specified by RFC 4627. This option makes the parser liberal in what it accepts.
-    spring.gson.long-serialization-policy= # Configures Gson to apply a specific serialization policy for Long and long objects.
-    spring.gson.pretty-printing=false # Configures Gson to output Json that fits in a page for pretty printing. This option only affects Json serialization.
-    spring.gson.serialize-nulls=false # Configure Gson to serialize null fields.
+	# GSON ({sc-spring-boot-autoconfigure}/gson/GsonProperties.{sc-ext}[GsonProperties])
+	spring.gson.date-format= # The format to use when serializing Date objects.
+	spring.gson.disable-html-escaping= # Whether to disable the escaping of HTML characters such as '<' '>' etc.
+	spring.gson.disable-inner-class-serialization= # Whether to exclude inner classes during serialization.
+	spring.gson.enable-complex-map-key-serialization= # Whether to enabled serialization of complex map keys (i.e. non-primitives).
+	spring.gson.exclude-fields-without-expose-annotation= # Whether to exclude all fields from consideration for serialization or deserialization that do not have the "Expose" annotation.
+	spring.gson.field-naming-policy= # The naming policy that should be applied to an object's field during serialization and deserialization.
+	spring.gson.generate-non-executable-json= # Whether to generate non executable JSON by prefixing the output with some special text.
+	spring.gson.lenient= # Whether to be lenient about parsing JSON that doesn't conform to RFC 4627.
+	spring.gson.long-serialization-policy= # Serialization policy for Long and long types.
+	spring.gson.pretty-printing= # Whether to output serialized JSON that fits in a page for pretty printing.
+	spring.gson.serialize-nulls= # Whether to to serialize null fields.
 
 	# JERSEY ({sc-spring-boot-autoconfigure}/jersey/JerseyProperties.{sc-ext}[JerseyProperties])
 	spring.jersey.application-path= # Path that serves as the base URI for the application. If specified, overrides the value of "@ApplicationPath".