source code and tests for jackson node operations

jackson/src/main/resources/node_example.json

@@ -0,0 +1,10 @@
+{
+	"name": 
+	{
+		"first": "Tatu",
+		"last": "Saloranta"
+	},
+
+	"title": "Jackson founder",
+	"company": "FasterXML"
+}

jackson/src/test/java/org/baeldung/jackson/node/ExampleStructure.java

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+package org.baeldung.jackson.node;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class ExampleStructure {
+    private static ObjectMapper mapper = new ObjectMapper();
+
+    static JsonNode getExampleRoot() throws IOException {
+        InputStream exampleInput = ExampleStructure.class.getClassLoader().getResourceAsStream("node_example.json");
+        JsonNode rootNode = mapper.readTree(exampleInput);
+        return rootNode;
+    }
+}

jackson/src/test/java/org/baeldung/jackson/node/MyBean.java

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+package org.baeldung.jackson.node;
+
+public class MyBean {
+    private int id;
+    private String name;
+
+    public MyBean() {
+    }
+
+    public MyBean(int id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

jackson/src/test/java/org/baeldung/jackson/test/JacksonNodeOperationTest.java

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+package org.baeldung.jackson.node;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import org.junit.Test;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+
+public class JacksonNodeOperationTest {
+    private static ObjectMapper mapper = new ObjectMapper();
+
+    @Test
+    public void giveAnObject_whenConvertingIntoANode_thenCorrect() {
+        MyBean fromValue = new MyBean(2016, "baeldung.com");
+
+        JsonNode node = mapper.valueToTree(fromValue);
+
+        assertEquals(2016, node.get("id").intValue());
+        assertEquals("baeldung.com", node.get("name").textValue());
+    }
+
+    @Test
+    public void givenANode_whenWritingOutAsAJsonString_thenCorrect() throws IOException {
+        final String pathToTestFile = "node_to_json_test.json";
+        char[] characterBuffer = new char[50];
+
+        JsonNode node = mapper.createObjectNode();
+        ((ObjectNode) node).put("id", 2016);
+        ((ObjectNode) node).put("name", "baeldung.com");
+
+        try (FileWriter outputStream = new FileWriter(pathToTestFile)) {
+            mapper.writeValue(outputStream, node);
+        }
+
+        try (FileReader inputStreamForAssertion = new FileReader(pathToTestFile)) {
+            inputStreamForAssertion.read(characterBuffer);
+        }
+        String textContentOfTestFile = new String(characterBuffer);
+
+        assertThat(textContentOfTestFile, containsString("2016"));
+        assertThat(textContentOfTestFile, containsString("baeldung.com"));
+
+        Files.delete(Paths.get(pathToTestFile));
+    }
+
+    @Test
+    public void givenANode_whenConvertingIntoAnObject_thenCorrect() throws JsonProcessingException {
+        JsonNode node = mapper.createObjectNode();
+        ((ObjectNode) node).put("id", 2016);
+        ((ObjectNode) node).put("name", "baeldung.com");
+
+        MyBean toValue = mapper.treeToValue(node, MyBean.class);
+
+        assertEquals(2016, toValue.getId());
+        assertEquals("baeldung.com", toValue.getName());
+    }
+
+    @Test
+    public void givenANode_whenAddingIntoATree_thenCorrect() throws IOException {
+        JsonNode rootNode = ExampleStructure.getExampleRoot();
+        ObjectNode addedNode = ((ObjectNode) rootNode).putObject("address");
+        addedNode.put("city", "Seattle").put("state", "Washington").put("country", "United States");
+
+        assertFalse(rootNode.path("address").isMissingNode());
+        assertEquals("Seattle", rootNode.path("address").path("city").textValue());
+        assertEquals("Washington", rootNode.path("address").path("state").textValue());
+        assertEquals("United States", rootNode.path("address").path("country").textValue());
+    }
+
+    @Test
+    public void givenANode_whenModifyingIt_thenCorrect() throws IOException {
+        String newString = "{\"nick\": \"cowtowncoder\"}";
+        JsonNode newNode = mapper.readTree(newString);
+
+        JsonNode rootNode = ExampleStructure.getExampleRoot();
+        ((ObjectNode) rootNode).set("name", newNode);
+
+        assertFalse(rootNode.path("name").path("nick").isMissingNode());
+        assertEquals("cowtowncoder", rootNode.path("name").path("nick").textValue());
+    }
+
+    @Test
+    public void givenANode_whenRemovingFromATree_thenCorrect() throws IOException {
+        JsonNode rootNode = ExampleStructure.getExampleRoot();
+        ((ObjectNode) rootNode).remove("company");
+
+        assertTrue(rootNode.path("company").isMissingNode());
+    }
+
+}