add methods copyResourceToTempFile() and tryCopyResourceToTempFile()

SVN: 1491

common/source/java/ch/systemsx/cisd/common/utilities/FileUtilities.java

@@ -19,10 +19,12 @@ package ch.systemsx.cisd.common.utilities;
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileFilter;
+import java.io.FileOutputStream;
 import java.io.FileReader;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.io.OutputStream;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.regex.Matcher;
@@ -477,8 +479,8 @@ public final class FileUtilities
      * 
      * @param defaultFileName the default name for the new file if the digit pattern could not be found (probably the
      *            starting file).
-     * @param regex pattern to find out the counter. If <code>null</code> then <code>"(\\d+)"</code> will be
-     *            taken. The given <var>regex</var> must contain <code>(\\d+)</code> or <code>([0-9]+)</code>.
+     * @param regex pattern to find out the counter. If <code>null</code> then <code>"(\\d+)"</code> will be taken.
+     *            The given <var>regex</var> must contain <code>(\\d+)</code> or <code>([0-9]+)</code>.
      */
     public final static File createNextNumberedFile(File path, Pattern regex, String defaultFileName)
     {
@@ -548,4 +550,62 @@ public final class FileUtilities
             return null;
         }
     }
+
+    /**
+     * Copies the resource with the given name to a temporary file.
+     * 
+     * @param resource The name of the resource to copy.
+     * @param prefix The prefix to use for the temporary name.
+     * @param postfix The postfix to use for the temporary name.
+     * @return The name of the temporary file.
+     * @throws IllegalArgumentException If the resource cannot be found in the class path.
+     * @throws CheckedExceptionTunnel If an {@link IOException} occurs.
+     */
+    public final static String copyResourceToTempFile(String resource, String prefix, String postfix)
+    {
+        final InputStream resourceStream = FileUtilities.class.getResourceAsStream(resource);
+        if (resourceStream == null)
+        {
+            throw new IllegalArgumentException("Resource '" + resource + "' not found.");
+        }
+        try
+        {
+            final File tempFile = File.createTempFile(prefix, postfix);
+            tempFile.deleteOnExit();
+            OutputStream fileStream = new FileOutputStream(tempFile);
+            try
+            {
+                IOUtils.copy(resourceStream, fileStream);
+            } finally
+            {
+                IOUtils.closeQuietly(fileStream);
+            }
+            return tempFile.getAbsolutePath();
+        } catch (IOException ex)
+        {
+            throw new CheckedExceptionTunnel(ex);
+        } finally
+        {
+            IOUtils.closeQuietly(resourceStream);
+        }
+    }
+    
+    /**
+     * Tries to copy the resource with the given name to a temporary file.
+     * 
+     * @param resource The name of the resource to copy.
+     * @param prefix The prefix to use for the temporary name.
+     * @param postfix The postfix to use for the temporary name.
+     * @return The name of the temporary file, or <code>null</code>, if the resource could not be copied.
+     */
+    public final static String tryCopyResourceToTempFile(String resource, String prefix, String postfix)
+    {
+        try
+        {
+            return copyResourceToTempFile(resource, prefix, postfix);
+        } catch (Exception ex)
+        {
+            return null;
+        }
+    }
 }

common/sourceTest/java/ch/systemsx/cisd/common/utilities/FileUtilitiesTest.java

@@ -18,17 +18,22 @@ package ch.systemsx.cisd.common.utilities;
 
 import static org.testng.AssertJUnit.assertEquals;
 import static org.testng.AssertJUnit.assertFalse;
+import static org.testng.AssertJUnit.assertNotNull;
 import static org.testng.AssertJUnit.assertNull;
+import static org.testng.AssertJUnit.assertTrue;
 import static org.testng.AssertJUnit.fail;
 
 import java.io.File;
+import java.io.FileInputStream;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.io.InputStream;
 import java.util.Arrays;
 import java.util.List;
 import java.util.regex.Pattern;
 
 import org.apache.commons.io.FilenameUtils;
+import org.apache.commons.io.IOUtils;
 import org.testng.annotations.BeforeSuite;
 import org.testng.annotations.Test;
 
@@ -235,4 +240,62 @@ public class FileUtilitiesTest
         assertFalse(relativeFile.isAbsolute());
         assertEquals("hello", relativeFile.getPath());
     }
+
+    @Test(expectedExceptions = IllegalArgumentException.class)
+    public final void testCopyResourceToTempFileIllegalResource()
+    {
+        FileUtilities.copyResourceToTempFile("nonexistent", "pre", "post");
+    }
+
+    @Test
+    public final void testCopyResourceToTempFile()
+    {
+        final String resourceName = "/ch/systemsx/cisd/common/utilities/FileUtilities.class";
+        final String absoluteTempFileName = FileUtilities.copyResourceToTempFile(resourceName, "pre", "post");
+        assertNotNull(absoluteTempFileName);
+        final File tempFile = new File(absoluteTempFileName);
+        final String tempFileName = tempFile.getName();
+        assertTrue(tempFile.exists());
+        assertTrue(tempFile.length() > 0);
+        assertTrue(tempFileName.startsWith("pre"));
+        assertTrue(tempFileName.endsWith("post"));
+        assertTrue(Arrays.equals(resourceToByteArray(resourceName), fileToByteArray(absoluteTempFileName)));
+
+    }
+
+    private byte[] resourceToByteArray(String resourcename)
+    {
+        final InputStream is = FileUtilitiesTest.class.getResourceAsStream(resourcename);
+        if (is == null)
+        {
+            return null;
+        }
+        try
+        {
+            return IOUtils.toByteArray(is);
+        } catch (IOException ex)
+        {
+            return null;
+        } finally
+        {
+            IOUtils.closeQuietly(is);
+        }
+    }
+
+    private byte[] fileToByteArray(String filename)
+    {
+        InputStream is = null;
+        try
+        {
+            is = new FileInputStream(filename);
+            return IOUtils.toByteArray(is);
+        } catch (IOException ex)
+        {
+            return null;
+        } finally
+        {
+            IOUtils.closeQuietly(is);
+        }
+
+    }
 }