├── .classpath
├── .gitignore
├── .project
├── .settings
    ├── org.eclipse.jdt.core.prefs
    └── org.eclipse.m2e.core.prefs
├── pom.xml
└── src
    ├── main
        └── java
        │   └── com
        │       └── dzone
        │           └── albanoj2
        │               └── examples
        │                   └── annotation
        │                       └── jsonserializer
        │                           ├── JsonField.java
        │                           ├── JsonSerializeException.java
        │                           └── JsonSerializer.java
    └── test
        └── java
            └── com
                └── dzone
                    └── albanoj2
                        └── examples
                            └── annotation
                                └── jsonserializer
                                    ├── JsonSerializerTest.java
                                    └── data
                                        └── Car.java


/.classpath:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <classpath>
 3 | 	<classpathentry kind="src" output="target/classes" path="src/main/java">
 4 | 		<attributes>
 5 | 			<attribute name="optional" value="true"/>
 6 | 			<attribute name="maven.pomderived" value="true"/>
 7 | 		</attributes>
 8 | 	</classpathentry>
 9 | 	<classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources">
10 | 		<attributes>
11 | 			<attribute name="maven.pomderived" value="true"/>
12 | 		</attributes>
13 | 	</classpathentry>
14 | 	<classpathentry kind="src" output="target/test-classes" path="src/test/java">
15 | 		<attributes>
16 | 			<attribute name="optional" value="true"/>
17 | 			<attribute name="maven.pomderived" value="true"/>
18 | 		</attributes>
19 | 	</classpathentry>
20 | 	<classpathentry excluding="**" kind="src" output="target/test-classes" path="src/test/resources">
21 | 		<attributes>
22 | 			<attribute name="maven.pomderived" value="true"/>
23 | 		</attributes>
24 | 	</classpathentry>
25 | 	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/J2SE-1.5">
26 | 		<attributes>
27 | 			<attribute name="maven.pomderived" value="true"/>
28 | 		</attributes>
29 | 	</classpathentry>
30 | 	<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
31 | 		<attributes>
32 | 			<attribute name="maven.pomderived" value="true"/>
33 | 		</attributes>
34 | 	</classpathentry>
35 | 	<classpathentry kind="output" path="target/classes"/>
36 | </classpath>
37 | 


--------------------------------------------------------------------------------
/.gitignore:
--------------------------------------------------------------------------------
 1 | target/
 2 | pom.xml.tag
 3 | pom.xml.releaseBackup
 4 | pom.xml.versionsBackup
 5 | pom.xml.next
 6 | release.properties
 7 | dependency-reduced-pom.xml
 8 | buildNumber.properties
 9 | .mvn/timing.properties
10 | 
11 | # Avoid ignoring Maven wrapper jar file (.jar files are usually ignored)
12 | !/.mvn/wrapper/maven-wrapper.jar


--------------------------------------------------------------------------------
/.project:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <projectDescription>
 3 | 	<name>json-serializer</name>
 4 | 	<comment></comment>
 5 | 	<projects>
 6 | 	</projects>
 7 | 	<buildSpec>
 8 | 		<buildCommand>
 9 | 			<name>org.eclipse.jdt.core.javabuilder</name>
10 | 			<arguments>
11 | 			</arguments>
12 | 		</buildCommand>
13 | 		<buildCommand>
14 | 			<name>org.eclipse.m2e.core.maven2Builder</name>
15 | 			<arguments>
16 | 			</arguments>
17 | 		</buildCommand>
18 | 	</buildSpec>
19 | 	<natures>
20 | 		<nature>org.eclipse.jdt.core.javanature</nature>
21 | 		<nature>org.eclipse.m2e.core.maven2Nature</nature>
22 | 	</natures>
23 | </projectDescription>
24 | 


--------------------------------------------------------------------------------
/.settings/org.eclipse.jdt.core.prefs:
--------------------------------------------------------------------------------
 1 | eclipse.preferences.version=1
 2 | org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
 3 | org.eclipse.jdt.core.compiler.codegen.methodParameters=do not generate
 4 | org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
 5 | org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
 6 | org.eclipse.jdt.core.compiler.compliance=1.8
 7 | org.eclipse.jdt.core.compiler.debug.lineNumber=generate
 8 | org.eclipse.jdt.core.compiler.debug.localVariable=generate
 9 | org.eclipse.jdt.core.compiler.debug.sourceFile=generate
10 | org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
11 | org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
12 | org.eclipse.jdt.core.compiler.problem.forbiddenReference=warning
13 | org.eclipse.jdt.core.compiler.source=1.8
14 | 


--------------------------------------------------------------------------------
/.settings/org.eclipse.m2e.core.prefs:
--------------------------------------------------------------------------------
1 | activeProfiles=
2 | eclipse.preferences.version=1
3 | resolveWorkspaceProjects=true
4 | version=1
5 | 


--------------------------------------------------------------------------------
/pom.xml:
--------------------------------------------------------------------------------
 1 | <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 2 | 	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 3 | 	<modelVersion>4.0.0</modelVersion>
 4 | 	<groupId>com.dzone.albanoj2.examples.annotation</groupId>
 5 | 	<artifactId>json-serializer</artifactId>
 6 | 	<version>0.0.1-SNAPSHOT</version>
 7 | 	<name>JsonSerializer</name>
 8 | 
 9 | 	<dependencies>
10 | 		<dependency>
11 | 			<groupId>junit</groupId>
12 | 			<artifactId>junit</artifactId>
13 | 			<version>4.12</version>
14 | 			<scope>test</scope>
15 | 		</dependency>
16 | 		<dependency>
17 | 			<groupId>org.hamcrest</groupId>
18 | 			<artifactId>hamcrest-all</artifactId>
19 | 			<version>1.3</version>
20 | 			<scope>test</scope>
21 | 		</dependency>
22 | 	</dependencies>
23 | </project>


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/src/main/java/com/dzone/albanoj2/examples/annotation/jsonserializer/JsonField.java:
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 1 | package com.dzone.albanoj2.examples.annotation.jsonserializer;
 2 | 
 3 | import java.lang.annotation.ElementType;
 4 | import java.lang.annotation.Retention;
 5 | import java.lang.annotation.RetentionPolicy;
 6 | import java.lang.annotation.Target;
 7 | 
 8 | @Retention(RetentionPolicy.RUNTIME)
 9 | @Target(ElementType.FIELD)
10 | public @interface JsonField {
11 | 	public String value() default "";
12 | }
13 | 


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/src/main/java/com/dzone/albanoj2/examples/annotation/jsonserializer/JsonSerializeException.java:
--------------------------------------------------------------------------------
 1 | package com.dzone.albanoj2.examples.annotation.jsonserializer;
 2 | 
 3 | public class JsonSerializeException extends Exception {
 4 | 
 5 | 	private static final long serialVersionUID = -8845242379503538623L;
 6 | 
 7 | 	public JsonSerializeException(String message) {
 8 | 		super(message);
 9 | 	}
10 | }
11 | 


--------------------------------------------------------------------------------
/src/main/java/com/dzone/albanoj2/examples/annotation/jsonserializer/JsonSerializer.java:
--------------------------------------------------------------------------------
 1 | package com.dzone.albanoj2.examples.annotation.jsonserializer;
 2 | 
 3 | import static java.util.Objects.requireNonNull;
 4 | import static java.util.stream.Collectors.joining;
 5 | 
 6 | import java.lang.reflect.Field;
 7 | import java.util.HashMap;
 8 | import java.util.Map;
 9 | 
10 | public class JsonSerializer {
11 | 
12 | 	public String serialize(Object object) throws JsonSerializeException {
13 | 		
14 | 		try {
15 | 			Class<?> objectClass = requireNonNull(object).getClass();
16 | 			Map<String, String> jsonElements = new HashMap<>();
17 | 			
18 | 			for (Field field: objectClass.getDeclaredFields()) {
19 | 				field.setAccessible(true);
20 | 				if (field.isAnnotationPresent(JsonField.class)) {
21 | 					jsonElements.put(getSerializedKey(field), (String) field.get(object));
22 | 				}
23 | 			}
24 | 			System.out.println(toJsonString(jsonElements));
25 | 			return toJsonString(jsonElements);
26 | 		}
27 | 		catch (IllegalAccessException e) {
28 | 			throw new JsonSerializeException(e.getMessage());
29 | 		}
30 | 	}
31 | 
32 | 	private String toJsonString(Map<String, String> jsonMap) {
33 | 		String elementsString = jsonMap.entrySet()
34 | 		        .stream()
35 | 		        .map(entry -> "\""  + entry.getKey() + "\":\"" + entry.getValue() + "\"")
36 | 		        .collect(joining(","));
37 | 		return "{" + elementsString + "}";
38 | 	}
39 | 	
40 | 	private static String getSerializedKey(Field field) {
41 | 		String annotationValue = field.getAnnotation(JsonField.class).value();
42 | 		
43 | 		if (annotationValue.isEmpty()) {
44 | 			return field.getName();
45 | 		}
46 | 		else {
47 | 			return annotationValue;
48 | 		}
49 | 	}
50 | }
51 | 


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/src/test/java/com/dzone/albanoj2/examples/annotation/jsonserializer/JsonSerializerTest.java:
--------------------------------------------------------------------------------
 1 | package com.dzone.albanoj2.examples.annotation.jsonserializer;
 2 | 
 3 | import static org.hamcrest.Matchers.isOneOf;
 4 | import static org.junit.Assert.assertThat;
 5 | 
 6 | import org.hamcrest.Matcher;
 7 | import org.junit.Test;
 8 | 
 9 | import com.dzone.albanoj2.examples.annotation.jsonserializer.data.Car;
10 | 
11 | public class JsonSerializerTest {
12 | 	
13 | 	@Test(expected = NullPointerException.class)
14 | 	public void serializeNullObjectEnsureNullPointerExceptionThrown() throws Exception {
15 | 		new JsonSerializer().serialize(null);
16 | 	}
17 | 
18 | 	@Test
19 | 	public void serializeCarObjectEnsureCorrectOutputJson() throws Exception {
20 | 		JsonSerializer serializer = new JsonSerializer();
21 | 		Car testCar = new Car("Ford", "F150", "2018");
22 | 		String json = serializer.serialize(testCar);
23 | 		assertThat(json, isExpectedCarJson(testCar));
24 | 	}
25 | 	
26 | 	private static Matcher<String> isExpectedCarJson(Car car) {
27 | 		return isOneOf(
28 | 			"{\"manufacturer\":\"" + car.getMake() + "\",\"model\":\"" + car.getModel() + "\"}",
29 | 			"{\"model\":\"" + car.getModel() + "\",\"manufacturer\":\"" + car.getMake() + "\"}"
30 | 		);
31 | 	}
32 | }
33 | 


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/src/test/java/com/dzone/albanoj2/examples/annotation/jsonserializer/data/Car.java:
--------------------------------------------------------------------------------
 1 | package com.dzone.albanoj2.examples.annotation.jsonserializer.data;
 2 | 
 3 | import com.dzone.albanoj2.examples.annotation.jsonserializer.JsonField;
 4 | 
 5 | public class Car {
 6 | 
 7 | 	@JsonField("manufacturer")
 8 | 	private final String make;
 9 | 	
10 | 	@JsonField
11 | 	private final String model;
12 | 	
13 | 	private final String year;
14 | 	
15 | 	public Car(String make, String model, String year) {
16 | 		this.make = make;
17 | 		this.model = model;
18 | 		this.year = year;
19 | 	}
20 | 	
21 | 	public String getMake() {
22 | 		return make;
23 | 	}
24 | 
25 | 	public String getModel() {
26 | 		return model;
27 | 	}
28 | 	
29 | 	public String getYear() {
30 | 		return year;
31 | 	}
32 | 
33 | 	@Override
34 | 	public String toString() {
35 | 		return year + " " + make + " " + model;
36 | 	}
37 | }
38 | 


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