BAEL-5657 - Reading JSON from a URL in Java (#12584)

* moving SpringBootPersistenceApplication class to its own package

* from com.baeldung to com.baeldung.logging to prevent it from loading
contexts from other applications.

* moving SpringBootPersistenceApplication class to its own package

* from com.baeldung to com.baeldung.logging to prevent it from loading
contexts from other applications.

* Spring Data MongoDB - Configure Connection

Ready for revision.

* fixed tests to reflect article changes

* BAEL-5657

* reverting BAEL-5657

* reverting BAEL-5657

* done

* reverting bael-5366

* revert bael-5366

* revert bael-3366

* including section 3

3. Using commons-io and org.json

* replacing tabs with spaces

jackson-modules/jackson-conversions-2/pom.xml

@@ -32,6 +32,18 @@
             <artifactId>jackson-dataformat-csv</artifactId>
             <version>${jackson.version}</version>
         </dependency>
+
+        <dependency>
+            <groupId>org.mock-server</groupId>
+            <artifactId>mockserver-netty</artifactId>
+            <version>${mockserver-netty.version}</version>
+            <scope>test</scope>        
+        </dependency>
+        <dependency>
+            <groupId>org.json</groupId>
+            <artifactId>json</artifactId>
+            <version>${json.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -44,4 +56,9 @@
         </resources>
     </build>
 
+    <properties>
+        <mockserver-netty.version>5.13.2</mockserver-netty.version>
+        <json.version>20220320</json.version>
+    </properties>
+
 </project>

jackson-modules/jackson-conversions-2/src/main/java/com/baeldung/jackson/jsonurlreader/JsonUrlReader.java

@@ -0,0 +1,62 @@
+package com.baeldung.jackson.jsonurlreader;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.nio.charset.Charset;
+
+import org.apache.commons.io.IOUtils;
+import org.json.JSONObject;
+
+import com.fasterxml.jackson.core.exc.StreamReadException;
+import com.fasterxml.jackson.databind.DatabindException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class JsonUrlReader {
+
+    public static void main(String[] args) throws StreamReadException, DatabindException, MalformedURLException, IOException {
+        String url = args[0];
+
+        JsonNode node = JsonUrlReader.get(url);
+        System.out.println(node.toPrettyString());
+    }
+
+    public static String stream(String url) throws IOException {
+        try (InputStream input = new URL(url).openStream()) {
+            InputStreamReader isr = new InputStreamReader(input, Charset.forName("UTF-8"));
+            BufferedReader reader = new BufferedReader(isr);
+            StringBuilder json = new StringBuilder();
+            int c;
+            while ((c = reader.read()) != -1) {
+                json.append((char) c);
+            }
+            return json.toString();
+        }
+    }
+
+    public static JsonNode get(String url) throws StreamReadException, DatabindException, MalformedURLException, IOException {
+        ObjectMapper mapper = new ObjectMapper();
+        JsonNode json = mapper.readTree(new URL(url));
+        return json;
+    }
+
+    public static <T> T get(String url, Class<T> type) throws StreamReadException, DatabindException, MalformedURLException, IOException {
+        ObjectMapper mapper = new ObjectMapper();
+        T entity = mapper.readValue(new URL(url), type);
+        return entity;
+    }
+
+    public static String getString(String url) throws StreamReadException, DatabindException, MalformedURLException, IOException {
+        return get(url).toPrettyString();
+    }
+
+    public static JSONObject getJson(String url) throws MalformedURLException, IOException {
+        String json = IOUtils.toString(new URL(url), Charset.forName("UTF-8"));
+        JSONObject object = new JSONObject(json);
+        return object;
+    }
+}

jackson-modules/jackson-conversions-2/src/main/java/com/baeldung/jackson/jsonurlreader/data/Example.java

@@ -0,0 +1,40 @@
+package com.baeldung.jackson.jsonurlreader.data;
+
+public class Example {
+    private String name;
+    private Integer n;
+    private Boolean real;
+
+    public Example() {
+    }
+
+    public Example(String name, Integer n, Boolean real) {
+        this.name = name;
+        this.n = n;
+        this.real = real;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Integer getN() {
+        return n;
+    }
+
+    public void setN(Integer n) {
+        this.n = n;
+    }
+
+    public Boolean getReal() {
+        return real;
+    }
+
+    public void setReal(Boolean real) {
+        this.real = real;
+    }
+}

jackson-modules/jackson-conversions-2/src/test/java/com/baeldung/jackson/jsonurlreader/JsonMockServer.java

@@ -0,0 +1,62 @@
+package com.baeldung.jackson.jsonurlreader;
+
+import static org.mockserver.integration.ClientAndServer.startClientAndServer;
+import static org.mockserver.model.HttpRequest.request;
+import static org.mockserver.model.HttpResponse.response;
+
+import java.io.IOException;
+import java.net.ServerSocket;
+
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.mockserver.client.MockServerClient;
+import org.mockserver.integration.ClientAndServer;
+import org.mockserver.model.HttpStatusCode;
+
+import com.baeldung.jackson.jsonurlreader.data.Example;
+
+public class JsonMockServer {
+    protected static final String JSON_RESPONSE = "{ \"name\": \"A\", \"n\": 1, \"real\": true }";
+    protected static final Example OBJECT_RESPONSE = new Example("A", 1, true);
+
+    protected static String serviceUrl;
+
+    private static final String SERVER_ADDRESS = "127.0.0.1";
+    private static final String PATH = "/sample-json";
+
+    private static ClientAndServer mockServer;
+    private static int serverPort;
+
+    @BeforeAll
+    static void startServer() throws IOException {
+        serverPort = getFreePort();
+        serviceUrl = "http://" + SERVER_ADDRESS + ":" + serverPort + PATH;
+
+        mockServer = startClientAndServer(serverPort);
+
+        mockJsonRequest();
+    }
+
+    @AfterAll
+    static void stopServer() {
+        mockServer.stop();
+    }
+
+    @SuppressWarnings("resource")
+    private static void mockJsonRequest() {
+        new MockServerClient(SERVER_ADDRESS, serverPort)
+          .when(request()
+            .withPath(PATH)
+            .withMethod("GET"))
+          .respond(response()
+            .withStatusCode(HttpStatusCode.OK_200.code())
+            .withBody(JSON_RESPONSE)
+        );
+    }
+
+    private static int getFreePort() throws IOException {
+        try (ServerSocket serverSocket = new ServerSocket(0)) {
+            return serverSocket.getLocalPort();
+        }
+    }
+}

jackson-modules/jackson-conversions-2/src/test/java/com/baeldung/jackson/jsonurlreader/JsonUrlReaderIntegrationTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.jackson.jsonurlreader;
+
+import static org.junit.Assert.assertEquals;
+
+import org.json.JSONObject;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.jackson.jsonurlreader.data.Example;
+import com.fasterxml.jackson.databind.JsonNode;
+
+public class JsonUrlReaderIntegrationTest extends JsonMockServer {
+
+    @Test
+    public void whenStreamUrl_thenJsonStringReturned() throws Exception {
+        String jsonNode = JsonUrlReader.stream(serviceUrl);
+
+        assertEquals(jsonNode, JSON_RESPONSE);
+    }
+
+    @Test
+    public void whenGetUrl_thenJsonNodeReturned() throws Exception {
+        JsonNode jsonNode = JsonUrlReader.get(serviceUrl);
+
+        assertEquals(jsonNode.get("name")
+            .textValue(), "A");
+        assertEquals(jsonNode.get("n")
+            .intValue(), 1);
+        assertEquals(jsonNode.get("real")
+            .booleanValue(), true);
+    }
+
+    @Test
+    public void givenType_whenGetUrl_thenTypeReturned() throws Exception {
+        Example object = JsonUrlReader.get(serviceUrl, Example.class);
+
+        Integer n = 1;
+        assertEquals(object.getName(), "A");
+        assertEquals(object.getN(), n);
+        assertEquals(object.getReal(), true);
+    }
+
+    @Test
+    public void whenGetJsonUrl_thenJsonObjectReturned() throws Exception {
+        JSONObject jsonObject = JsonUrlReader.getJson(serviceUrl);
+
+        assertEquals(jsonObject.getString("name"), "A");
+        assertEquals(jsonObject.getInt("n"), 1);
+        assertEquals(jsonObject.getBoolean("real"), true);
+    }
+}