Merge pull request #14670 from manfred106/BAEL-6894-close-iostream

BAEL-6894: Closing Java IO Streams

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

@@ -54,6 +54,13 @@
             </resource>
         </resources>
         <plugins>
+            <plugin>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>11</source>
+                    <target>11</target>
+                </configuration>
+            </plugin>
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>exec-maven-plugin</artifactId>

core-java-modules/core-java-io/src/test/java/com/baeldung/close/StreamCloseUnitTest.java

@@ -0,0 +1,118 @@
+package com.baeldung.close;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import java.io.*;
+
+import org.apache.commons.io.IOUtils;
+import org.apache.commons.io.input.AutoCloseInputStream;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+@RunWith(MockitoJUnitRunner.class)
+public class StreamCloseUnitTest {
+
+    private static final Logger log = LoggerFactory.getLogger(StreamCloseUnitTest.class);
+
+    @Mock
+    private OutputStream wrappedOutputStream;
+
+    @Mock
+    private InputStream wrappedInputStream;
+
+    @Test
+    public void whenStreamClosedByFinally_thenIOStreamsCloseCalled() throws IOException {
+
+        InputStream inputStream = null;
+        OutputStream outputStream = null;
+
+        try {
+            inputStream = new BufferedInputStream(wrappedInputStream);
+            outputStream = new BufferedOutputStream(wrappedOutputStream);
+        }
+        finally {
+            try {
+                if (inputStream != null)
+                    inputStream.close();
+            }
+            catch (IOException ioe1) {
+                log.error("Cannot close InputStream");
+            }
+            try {
+                if (outputStream != null)
+                    outputStream.close();
+            }
+            catch (IOException ioe2) {
+                log.error("Cannot close OutputStream");
+            }
+        }
+
+        verify(wrappedInputStream).close();
+        verify(wrappedOutputStream).close();
+    }
+
+    @Test
+    public void whenStreamClosedByCloseQuietly_thenIOStreamsCloseCalled() throws IOException {
+
+        InputStream inputStream = null;
+        OutputStream outputStream = null;
+
+        try {
+            inputStream = new BufferedInputStream(wrappedInputStream);
+            outputStream = new BufferedOutputStream(wrappedOutputStream);
+        }
+        finally {
+            IOUtils.closeQuietly(inputStream);
+            IOUtils.closeQuietly(outputStream);
+        }
+
+        verify(wrappedInputStream).close();
+        verify(wrappedOutputStream).close();
+    }
+
+    @Test
+    public void whenFinishReadOnAutoCloseInputStream_thenInputStreamsCloseCalled() throws IOException {
+
+        // Mimic no more data in the InputStream
+        when(wrappedInputStream.read(any(byte[].class))).thenReturn(-1);
+
+        InputStream inputStream = AutoCloseInputStream.builder().setInputStream(wrappedInputStream).get();
+
+        byte[] buffer = new byte[256];
+        while (inputStream.read(buffer) != -1) {
+        }
+
+        verify(wrappedInputStream).close();
+    }
+
+    @Test
+    public void whenStreamClosedByWithResources_thenIOStreamsCloseCalled() throws IOException {
+
+        try (BufferedInputStream inputStream = new BufferedInputStream(wrappedInputStream);
+            BufferedOutputStream outputStream = new BufferedOutputStream(wrappedOutputStream)) {
+        }
+
+        verify(wrappedInputStream).close();
+        verify(wrappedOutputStream).close();
+    }
+
+    @Test
+    public void whenStreamClosedByWithResourcesJava9_thenIOStreamsCloseCalled() throws IOException {
+
+        InputStream inputStream = new BufferedInputStream(wrappedInputStream);
+        OutputStream outputStream = new BufferedOutputStream(wrappedOutputStream);
+
+        try (inputStream; outputStream) {
+        }
+
+        verify(wrappedInputStream).close();
+        verify(wrappedOutputStream).close();
+    }
+
+}