BAEL-3603 Add test examples for Java IO versus NIO article

core-java-modules/core-java-io-2/pom.xml

@@ -45,6 +45,14 @@
             <version>${assertj.version}</version>
             <scope>test</scope>
         </dependency>
+        <!-- https://mvnrepository.com/artifact/com.github.tomakehurst/wiremock -->
+        <dependency>
+            <groupId>com.github.tomakehurst</groupId>
+            <artifactId>wiremock</artifactId>
+            <version>2.26.3</version>
+            <scope>test</scope>
+        </dependency>
+
     </dependencies>
 
     <build>

core-java-modules/core-java-io-2/src/test/java/com/baeldung/blockingnonblocking/BlockingClientUnitTest.java

@@ -0,0 +1,51 @@
+package com.baeldung.blockingnonblocking;
+
+import com.github.tomakehurst.wiremock.junit.WireMockRule;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+
+import java.io.*;
+import java.net.Socket;
+
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
+import static com.github.tomakehurst.wiremock.core.WireMockConfiguration.wireMockConfig;
+import static org.junit.Assert.assertTrue;
+
+public class BlockingClientUnitTest {
+    private static final String REQUESTED_RESOURCE = "/test.json";
+
+    @Rule public WireMockRule wireMockRule = new WireMockRule(wireMockConfig().dynamicPort());
+
+    @Before
+    public void setup() {
+        stubFor(get(urlEqualTo(REQUESTED_RESOURCE)).willReturn(aResponse()
+          .withStatus(200)
+          .withBody("{ \"response\" : \"It worked!\" }\r\n\r\n")));
+    }
+
+    @Test
+    public void givenJavaIOSocket_whenReadingAndWritingWithStreams_thenReadSuccessfully() throws IOException {
+        // given an IO socket and somewhere to store our result
+        Socket socket = new Socket("localhost", wireMockRule.port());
+        StringBuilder ourStore = new StringBuilder();
+
+        // when we write and read (using try-with-resources so our resources are auto-closed)
+        try (InputStream serverInput = socket.getInputStream();
+          BufferedReader reader = new BufferedReader(new InputStreamReader(serverInput));
+          OutputStream clientOutput = socket.getOutputStream();
+          PrintWriter writer = new PrintWriter(new OutputStreamWriter(clientOutput))) {
+            writer.print("GET " + REQUESTED_RESOURCE + " HTTP/1.0\r\n\r\n");
+            writer.flush(); // important - without this the request is never sent, and the test will hang on readLine()
+
+            for (String line; (line = reader.readLine()) != null; ) {
+                ourStore.append(line);
+            }
+        }
+
+        // then we read and saved our data
+        assertTrue(ourStore
+          .toString()
+          .contains("It worked!"));
+    }
+}

core-java-modules/core-java-io-2/src/test/java/com/baeldung/blockingnonblocking/NonBlockingClientUnitTest.java

@@ -0,0 +1,94 @@
+package com.baeldung.blockingnonblocking;
+
+import com.github.tomakehurst.wiremock.junit.WireMockRule;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.nio.channels.SocketChannel;
+import java.nio.charset.Charset;
+import java.nio.charset.CharsetDecoder;
+import java.nio.charset.StandardCharsets;
+
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
+import static com.github.tomakehurst.wiremock.core.WireMockConfiguration.wireMockConfig;
+import static org.junit.Assert.assertTrue;
+
+public class NonBlockingClientUnitTest {
+    private String REQUESTED_RESOURCE = "/test.json";
+
+    @Rule public WireMockRule wireMockRule = new WireMockRule(wireMockConfig().dynamicPort());
+
+    @Before
+    public void setup() {
+        stubFor(get(urlEqualTo(REQUESTED_RESOURCE)).willReturn(aResponse()
+          .withStatus(200)
+          .withBody("{ \"response\" : \"It worked!\" }")));
+    }
+
+    @Test
+    public void givenJavaNIOSocketChannel_whenReadingAndWriting_thenUseBuffers() throws IOException {
+        // given a NIO SocketChannel and a charset
+        InetSocketAddress address = new InetSocketAddress("localhost", wireMockRule.port());
+        SocketChannel socketChannel = SocketChannel.open(address);
+        Charset charset = StandardCharsets.UTF_8;
+
+        // when we write and read using buffers
+        socketChannel.write(charset.encode(CharBuffer.wrap("GET " + REQUESTED_RESOURCE + " HTTP/1.0\r\n\r\n")));
+
+        ByteBuffer buffer = ByteBuffer.allocate(8); // or allocateDirect if we need direct memory access
+        CharBuffer charBuffer = CharBuffer.allocate(8192);
+        CharsetDecoder decoder = charset.newDecoder();
+        StringBuilder ourStore = new StringBuilder();
+        while (socketChannel.read(buffer) != -1 || buffer.position() > 0) {
+            buffer.flip();
+            storeBufferContents(buffer, charBuffer, decoder, ourStore);
+            buffer.compact();
+        }
+        socketChannel.close();
+
+        // then we read and saved our data
+        assertTrue(ourStore
+          .toString()
+          .contains("It worked!"));
+    }
+
+    @Test
+    public void givenJavaNIO_whenReadingAndWriting_thenSmallBuffers() throws IOException {
+        // given a NIO SocketChannel and a charset
+        InetSocketAddress address = new InetSocketAddress("localhost", wireMockRule.port());
+        SocketChannel socket = SocketChannel.open(address);
+        Charset charset = StandardCharsets.UTF_8;
+
+        // when we write and read using buffers that are too small for our message
+        socket.write(charset.encode(CharBuffer.wrap("GET " + REQUESTED_RESOURCE + " HTTP/1.0\r\n\r\n")));
+
+        ByteBuffer buffer = ByteBuffer.allocate(8); // or allocateDirect if we need direct memory access
+        CharBuffer charBuffer = CharBuffer.allocate(8);
+        CharsetDecoder decoder = charset.newDecoder();
+        StringBuilder ourStore = new StringBuilder();
+        while (socket.read(buffer) != -1 || buffer.position() > 0) {
+            buffer.flip();
+            storeBufferContents(buffer, charBuffer, decoder, ourStore);
+            buffer.compact();
+        }
+        socket.close();
+
+        // then we read and saved our data
+        assertTrue(ourStore
+          .toString()
+          .contains("It worked!"));
+    }
+
+    void storeBufferContents(ByteBuffer buffer, CharBuffer charBuffer, CharsetDecoder decoder, StringBuilder ourStore) {
+        decoder.decode(buffer, charBuffer, true);
+        charBuffer.flip();
+        ourStore.append(charBuffer);
+        charBuffer.clear();
+    }
+
+}