BAEL-2037 - Code for mini-article (#4923)

* BAEL-2037 - Code for mini-article

* BAEL-2037 - Fixes after editors review

* Fixing dependencies

* Change File Reader

* Formatting

* Fix imports

* Rename test class

json/pom.xml

@@ -33,6 +33,20 @@
             <artifactId>json</artifactId>
             <version>20171018</version>
         </dependency>
+        
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+        <!-- https://search.maven.org/search?q=g:org.glassfish%20AND%20a:javax.json&core=gav  -->
+        <dependency>
+            <groupId>org.glassfish</groupId>
+            <artifactId>javax.json</artifactId>
+            <version>1.1.2</version>
+        </dependency>
+        
     </dependencies>
 
     <properties>

json/src/main/java/com/baeldung/jsonpointer/JsonPointerCrud.java

@@ -0,0 +1,95 @@
+package com.baeldung.jsonpointer;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import javax.json.Json;
+import javax.json.JsonObject;
+import javax.json.JsonPointer;
+import javax.json.JsonReader;
+import javax.json.JsonString;
+import javax.json.JsonStructure;
+
+public class JsonPointerCrud {
+
+    private JsonStructure jsonStructure = null;
+
+    public JsonPointerCrud(String fileName) throws IOException {
+
+        try (JsonReader reader = Json.createReader(Files.newBufferedReader(Paths.get(fileName)))) {
+            jsonStructure = reader.read();
+        } catch (FileNotFoundException e) {
+            System.out.println("Error to open json file: " + e.getMessage());
+        }
+
+    }
+
+    public JsonPointerCrud(InputStream stream) {
+
+        JsonReader reader = Json.createReader(stream);
+        jsonStructure = reader.read();
+        reader.close();
+
+    }
+
+    public JsonStructure insert(String key, String value) {
+
+        JsonPointer jsonPointer = Json.createPointer("/" + key);
+        JsonString jsonValue = Json.createValue(value);
+        jsonStructure = jsonPointer.add(jsonStructure, jsonValue);
+
+        return jsonStructure;
+
+    }
+
+    public JsonStructure update(String key, String newValue) {
+
+        JsonPointer jsonPointer = Json.createPointer("/" + key);
+        JsonString jsonNewValue = Json.createValue(newValue);
+        jsonStructure = jsonPointer.replace(jsonStructure, jsonNewValue);
+
+        return jsonStructure;
+    }
+
+    public JsonStructure delete(String key) {
+
+        JsonPointer jsonPointer = Json.createPointer("/" + key);
+        jsonPointer.getValue(jsonStructure);
+        jsonStructure = jsonPointer.remove(jsonStructure);
+
+        return jsonStructure;
+
+    }
+
+    public String fetchValueFromKey(String key) {
+        JsonPointer jsonPointer = Json.createPointer("/" + key);
+        JsonString jsonString = (JsonString) jsonPointer.getValue(jsonStructure);
+
+        return jsonString.getString();
+    }
+
+    public String fetchListValues(String key) {
+        JsonPointer jsonPointer = Json.createPointer("/" + key);
+        JsonObject jsonObject = (JsonObject) jsonPointer.getValue(jsonStructure);
+
+        return jsonObject.toString();
+    }
+
+    public String fetchFullJSON() {
+        JsonPointer jsonPointer = Json.createPointer("");
+        JsonObject jsonObject = (JsonObject) jsonPointer.getValue(jsonStructure);
+
+        return jsonObject.toString();
+
+    }
+
+    public boolean check(String key) {
+        JsonPointer jsonPointer = Json.createPointer("/" + key);
+        boolean found = jsonPointer.containsValue(jsonStructure);
+
+        return found;
+    }
+}

json/src/test/java/com/baeldung/jsonpointer/JsonPointerCrudUnitTest.java

@@ -0,0 +1,59 @@
+package com.baeldung.jsonpointer;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+public class JsonPointerCrudUnitTest {
+
+    @Test
+    public void testJsonPointerCrudForAddress() {
+
+        JsonPointerCrud jsonPointerCrud = new JsonPointerCrud(JsonPointerCrudUnitTest.class.getResourceAsStream("/address.json"));
+
+        assertFalse(jsonPointerCrud.check("city"));
+
+        // insert a value
+        jsonPointerCrud.insert("city", "Rio de Janeiro");
+
+        assertTrue(jsonPointerCrud.check("city"));
+
+        // fetch full json
+        String fullJSON = jsonPointerCrud.fetchFullJSON();
+
+        assertTrue(fullJSON.contains("name"));
+
+        assertTrue(fullJSON.contains("city"));
+
+        // fetch value
+        String cityName = jsonPointerCrud.fetchValueFromKey("city");
+
+        assertEquals(cityName, "Rio de Janeiro");
+
+        // update value
+        jsonPointerCrud.update("city", "Sao Paulo");
+
+        // fetch value
+        cityName = jsonPointerCrud.fetchValueFromKey("city");
+
+        assertEquals(cityName, "Sao Paulo");
+
+        // delete
+        jsonPointerCrud.delete("city");
+
+        assertFalse(jsonPointerCrud.check("city"));
+
+    }
+
+    @Test
+    public void testJsonPointerCrudForBooks() {
+
+        JsonPointerCrud jsonPointerCrud = new JsonPointerCrud(JsonPointerCrudUnitTest.class.getResourceAsStream("/books.json"));
+
+        // fetch value
+        String book = jsonPointerCrud.fetchListValues("books/1");
+
+        assertEquals(book, "{\"title\":\"Title 2\",\"author\":\"John Doe\"}");
+
+    }
+}

json/src/test/resources/address.json

@@ -0,0 +1,4 @@
+{
+    "name": "Customer 01",
+    "street name": "Street 01"
+}

json/src/test/resources/books.json

@@ -0,0 +1,7 @@
+{
+    "library": "My Personal Library",
+    "books": [
+        { "title":"Title 1", "author":"Jane Doe" },
+        { "title":"Title 2", "author":"John Doe" }
+    ]
+}