Jackson Map Serialize/Deserialize (#1511)

* Solr w Apache SolrJ

* Solr w Apache SolrJ

* updated test names and moved add to @before method

* create apache-solrj module, moved code from spring-data-solr

* More examples for indexing,delete,and query for solrj

* More examples for indexing,delete,and query for solrj

* Jackson Map Serialize/Deserialize

* Jackson Map Serialize/Deserialize

jackson/src/main/java/com/baeldung/jackson/entities/MyPair.java

@@ -0,0 +1,80 @@
+package com.baeldung.jackson.entities;
+
+import com.fasterxml.jackson.annotation.JsonValue;
+
+public class MyPair {
+
+	private String first;
+	private String second;
+
+	public MyPair(String first, String second) {
+		this.first = first;
+		this.second = second;
+	}
+
+	public MyPair(String both) {
+		String[] pairs = both.split("and");
+		this.first = pairs[0].trim();
+		this.second = pairs[1].trim();
+	}
+
+	@Override
+	@JsonValue
+	public String toString() {
+		return first + " and " + second;
+	}
+
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		result = prime * result + ((first == null) ? 0 : first.hashCode());
+		result = prime * result + ((second == null) ? 0 : second.hashCode());
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) {
+			return true;
+		}
+		if (obj == null) {
+			return false;
+		}
+		if (!(obj instanceof MyPair)) {
+			return false;
+		}
+		MyPair other = (MyPair) obj;
+		if (first == null) {
+			if (other.first != null) {
+				return false;
+			}
+		} else if (!first.equals(other.first)) {
+			return false;
+		}
+		if (second == null) {
+			if (other.second != null) {
+				return false;
+			}
+		} else if (!second.equals(other.second)) {
+			return false;
+		}
+		return true;
+	}
+
+	public String getFirst() {
+		return first;
+	}
+
+	public void setFirst(String first) {
+		this.first = first;
+	}
+
+	public String getSecond() {
+		return second;
+	}
+
+	public void setSecond(String second) {
+		this.second = second;
+	}
+}

jackson/src/main/java/com/baeldung/jackson/serialization/MyPairSerializer.java

@@ -0,0 +1,25 @@
+package com.baeldung.jackson.serialization;
+
+import java.io.IOException;
+import java.io.StringWriter;
+
+import com.baeldung.jackson.entities.MyPair;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializerProvider;
+
+public class MyPairSerializer extends JsonSerializer<MyPair> {
+
+	private final ObjectMapper mapper = new ObjectMapper();
+
+	@Override
+	public void serialize(MyPair value, JsonGenerator gen,
+			SerializerProvider serializers) throws IOException,
+			JsonProcessingException {
+		StringWriter writer = new StringWriter();
+		mapper.writeValue(writer, value);
+		gen.writeFieldName(writer.toString());
+	}
+}

jackson/src/test/java/com/baeldung/jackson/deserialization/JacksonMapDeserializeTest.java

@@ -0,0 +1,63 @@
+package com.baeldung.jackson.deserialization;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.baeldung.jackson.entities.MyPair;
+import com.fasterxml.jackson.core.JsonParseException;
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class JacksonMapDeserializeTest {
+
+	private Map<MyPair, String> map;
+	private Map<MyPair, MyPair> cmap;
+
+	@Test
+	public void whenSimpleMapDeserialize_thenCorrect()
+			throws JsonParseException, JsonMappingException, IOException {
+
+		final String jsonInput = "{\"key\": \"value\"}";
+		final ObjectMapper mapper = new ObjectMapper();
+		TypeReference<HashMap<String, String>> typeRef = new TypeReference<HashMap<String, String>>() {
+		};
+
+		final Map<String, String> map = mapper.readValue(jsonInput, typeRef);
+
+		Assert.assertEquals("value", map.get("key"));
+	}
+
+	@Test
+	public void whenObjectStringMapDeserialize_thenCorrect()
+			throws JsonParseException, JsonMappingException, IOException {
+
+		final String jsonInput = "{\"Abbott and Costello\" : \"Comedy\"}";
+		final ObjectMapper mapper = new ObjectMapper();
+
+		TypeReference<HashMap<MyPair, String>> typeRef = new TypeReference<HashMap<MyPair, String>>() {
+		};
+		map = mapper.readValue(jsonInput, typeRef);
+
+		Assert.assertEquals("Comedy", map.get(new MyPair("Abbott", "Costello")));
+	}
+
+	@Test
+	public void whenObjectObjectMapDeserialize_thenCorrect()
+			throws JsonParseException, JsonMappingException, IOException {
+
+		final String jsonInput = "{\"Abbott and Costello\" : \"Comedy and 1940s\"}";
+		final ObjectMapper mapper = new ObjectMapper();
+		TypeReference<HashMap<MyPair, MyPair>> typeRef = new TypeReference<HashMap<MyPair, MyPair>>() {
+		};
+
+		cmap = mapper.readValue(jsonInput, typeRef);
+
+		Assert.assertEquals(new MyPair("Comedy", "1940s"),
+				cmap.get(new MyPair("Abbott", "Costello")));
+	}
+}

jackson/src/test/java/com/baeldung/jackson/serialization/JacksonMapSerializeTest.java

@@ -0,0 +1,71 @@
+package com.baeldung.jackson.serialization;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.baeldung.jackson.entities.MyPair;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import com.fasterxml.jackson.databind.ser.std.MapSerializer;
+
+public class JacksonMapSerializeTest {
+
+	@JsonSerialize(keyUsing = MyPairSerializer.class)
+	private Map<MyPair, String> map;
+
+	@JsonSerialize(keyUsing = MapSerializer.class)
+	private Map<MyPair, MyPair> cmap;
+
+	@JsonSerialize(keyUsing = MyPairSerializer.class)
+	private MyPair mapKey;
+
+	@JsonSerialize(keyUsing = MyPairSerializer.class)
+	private MyPair mapValue;
+
+	@Test
+	public void whenSimpleMapSerialize_thenCorrect()
+			throws JsonProcessingException {
+
+		Map<String, String> map = new HashMap<String, String>();
+		map.put("key", "value");
+
+		final ObjectMapper mapper = new ObjectMapper();
+		final String jsonResult = mapper.writeValueAsString(map);
+
+		Assert.assertEquals("{\"key\":\"value\"}", jsonResult);
+	}
+
+	@Test
+	public void whenCustomObjectStringMapSerialize_thenCorrect()
+			throws JsonProcessingException {
+
+		map = new HashMap<MyPair, String>();
+		MyPair key = new MyPair("Abbott", "Costello");
+		map.put(key, "Comedy");
+
+		final ObjectMapper mapper = new ObjectMapper();
+		final String jsonResult = mapper.writeValueAsString(map);
+
+		Assert.assertEquals("{\"Abbott and Costello\":\"Comedy\"}", jsonResult);
+	}
+
+	@Test
+	public void whenCustomObjectObjectMapSerialize_thenCorrect()
+			throws JsonProcessingException {
+
+		cmap = new HashMap<MyPair, MyPair>();
+		mapKey = new MyPair("Abbott", "Costello");
+		mapValue = new MyPair("Comedy", "1940's");
+		cmap.put(mapKey, mapValue);
+
+		final ObjectMapper mapper = new ObjectMapper();
+		final String jsonResult = mapper.writeValueAsString(cmap);
+
+		Assert.assertEquals("{\"Abbott and Costello\":\"Comedy and 1940's\"}",
+				jsonResult);
+	}
+}