trunk/src/testcases/org/apache/poi/poifs/nio/TestDataSource.java

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   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
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       http://www.apache.org/licenses/LICENSE-2.0

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   distributed under the License is distributed on an "AS IS" BASIS,
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   See the License for the specific language governing permissions and
   limitations under the License.
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package org.apache.poi.poifs.nio;

import junit.framework.TestCase;
import org.apache.poi.POIDataSamples;
import org.apache.poi.util.IOUtils;
import org.apache.poi.util.TempFile;

import java.io.*;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;

/**
 * Tests for the datasource implementations
 */
public class TestDataSource extends TestCase
{
   private static POIDataSamples data = POIDataSamples.getPOIFSInstance();
   
   public void testFile() throws Exception {
      File f = data.getFile("Notes.ole2");
      
      FileBackedDataSource ds = new FileBackedDataSource(f);
      try {
          checkDataSource(ds, false);
      } finally {
          ds.close();
      }
      
      // try a second time
      ds = new FileBackedDataSource(f);
      try {
          checkDataSource(ds, false);
      } finally {
          ds.close();
      }
   }

   public void testFileWritable() throws Exception {
       File temp = TempFile.createTempFile("TestDataSource", ".test");
       try {
           writeDataToFile(temp);
       
           FileBackedDataSource ds = new FileBackedDataSource(temp, false);
           try {
               checkDataSource(ds, true);
           } finally {
               ds.close();
           }
           
           // try a second time
           ds = new FileBackedDataSource(temp, false);
           try {
               checkDataSource(ds, true);
           } finally {
               ds.close();
           }

           writeDataToFile(temp);
       } finally {
           assertTrue(temp.exists());
           assertTrue("Could not delete file " + temp, temp.delete());
       }
    }


   public void testRewritableFile() throws Exception {
       File temp = TempFile.createTempFile("TestDataSource", ".test");
       try {
           writeDataToFile(temp);
           
           FileBackedDataSource ds = new FileBackedDataSource(temp, true);
           try {
               ByteBuffer buf = ds.read(0, 10);
               assertNotNull(buf);
               buf = ds.read(8, 0x400);
               assertNotNull(buf);
           } finally {
               ds.close();
           }
           
           // try a second time
           ds = new FileBackedDataSource(temp, true);
           try {
               ByteBuffer buf = ds.read(0, 10);
               assertNotNull(buf);
               buf = ds.read(8, 0x400);
               assertNotNull(buf);
           } finally {
               ds.close();
           }
           
           writeDataToFile(temp);
       } finally {
           assertTrue(temp.exists());
           assertTrue(temp.delete());
       }
    }

    private void writeDataToFile(File temp) throws IOException {
        OutputStream str = new FileOutputStream(temp);
           try {
               InputStream in = data.openResourceAsStream("Notes.ole2");
               try {
                   IOUtils.copy(in, str);
               } finally {
                   in.close();
               }
           } finally {
               str.close();
           }
    }
    
    private void checkDataSource(FileBackedDataSource ds, boolean writeable) throws IOException {
        assertEquals(writeable, ds.isWriteable());
        assertNotNull(ds.getChannel());
        
        // rewriting changes the size
        if(writeable) {
            assertTrue("Had: " + ds.size(), ds.size() == 8192 || ds.size() == 8198); 
        } else {
            assertEquals(8192, ds.size());
        }

        // Start of file
        ByteBuffer bs;
        bs = ds.read(4, 0);
        assertEquals(4, bs.capacity());
        assertEquals(0, bs.position());
        assertEquals(0xd0 - 256, bs.get(0));
        assertEquals(0xcf - 256, bs.get(1));
        assertEquals(0x11, bs.get(2));
        assertEquals(0xe0 - 256, bs.get(3));
        assertEquals(0xd0 - 256, bs.get());
        assertEquals(0xcf - 256, bs.get());
        assertEquals(0x11, bs.get());
        assertEquals(0xe0 - 256, bs.get());

        // Mid way through
        bs = ds.read(8, 0x400);
        assertEquals(8, bs.capacity());
        assertEquals(0, bs.position());
        assertEquals((byte) 'R', bs.get(0));
        assertEquals(0, bs.get(1));
        assertEquals((byte) 'o', bs.get(2));
        assertEquals(0, bs.get(3));
        assertEquals((byte) 'o', bs.get(4));
        assertEquals(0, bs.get(5));
        assertEquals((byte) 't', bs.get(6));
        assertEquals(0, bs.get(7));

        // Can go to the end, but not past it
        bs = ds.read(8, 8190);
        assertEquals(0, bs.position()); // TODO How best to warn of a short read?

        // Can't go off the end
        try {
            ds.read(4, 8192);
            if(!writeable) {
                fail("Shouldn't be able to read off the end of the file");
            }
        } catch (IndexOutOfBoundsException e) {
            // expected here
        }
    }

   public void testByteArray() throws Exception {
      byte[] data = new byte[256];
      byte b;
      for(int i=0; i<data.length; i++) {
         b = (byte)i;
         data[i] = b;
      }
      
      ByteArrayBackedDataSource ds = new ByteArrayBackedDataSource(data);
      
      // Start
      ByteBuffer bs; 
      bs = ds.read(4, 0);
      assertEquals(0, bs.position());
      assertEquals(0x00, bs.get());
      assertEquals(0x01, bs.get());
      assertEquals(0x02, bs.get());
      assertEquals(0x03, bs.get());
      
      // Middle
      bs = ds.read(4, 100);
      assertEquals(100, bs.position());
      assertEquals(100, bs.get());
      assertEquals(101, bs.get());
      assertEquals(102, bs.get());
      assertEquals(103, bs.get());
      
      // End
      bs = ds.read(4, 252);
      assertEquals(-4, bs.get());
      assertEquals(-3, bs.get());
      assertEquals(-2, bs.get());
      assertEquals(-1, bs.get());
      
      // Off the end
      bs = ds.read(4, 254);
      assertEquals(-2, bs.get());
      assertEquals(-1, bs.get());
      try {
         bs.get();
         fail("Shouldn't be able to read off the end");
      } catch(BufferUnderflowException e) {
          // expected here
      }

      // Past the end
      try {
         ds.read(4, 256);
         fail("Shouldn't be able to read off the end");
      } catch(IndexOutOfBoundsException e) {
          // expected here
      }
      
      
      // Overwrite
      bs = ByteBuffer.allocate(4);
      bs.put(0, (byte)-55);
      bs.put(1, (byte)-54);
      bs.put(2, (byte)-53);
      bs.put(3, (byte)-52);
      
      assertEquals(256, ds.size());
      ds.write(bs, 40);
      assertEquals(256, ds.size());
      bs = ds.read(4, 40);
      
      assertEquals(-55, bs.get());
      assertEquals(-54, bs.get());
      assertEquals(-53, bs.get());
      assertEquals(-52, bs.get());
      
      // Append
      bs = ByteBuffer.allocate(4);
      bs.put(0, (byte)-55);
      bs.put(1, (byte)-54);
      bs.put(2, (byte)-53);
      bs.put(3, (byte)-52);
      
      assertEquals(256, ds.size());
      ds.write(bs, 256);
      assertEquals(260, ds.size());
      
      bs = ds.read(4, 256);
      assertEquals(256, bs.position());
      assertEquals(-55, bs.get());
      assertEquals(-54, bs.get());
      assertEquals(-53, bs.get());
      assertEquals(-52, bs.get());
   }
}