diff options
| author | Brian S. O'Neill <bronee@gmail.com> | 2006-08-30 02:06:57 +0000 |
|---|---|---|
| committer | Brian S. O'Neill <bronee@gmail.com> | 2006-08-30 02:06:57 +0000 |
| commit | 21ffac73f08766ea06a289028f7479d04cb0ccff (patch) | |
| tree | 88e292be0cb4f8813a075f99062baf3a0eaa9763 /src/main/java/com/amazon/carbonado/lob/AbstractBlob.java | |
| parent | 04b06d8fa2ced539126f74f4d8a19c29b62c5730 (diff) | |
Add LOB support
Diffstat (limited to 'src/main/java/com/amazon/carbonado/lob/AbstractBlob.java')
| -rw-r--r-- | src/main/java/com/amazon/carbonado/lob/AbstractBlob.java | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/src/main/java/com/amazon/carbonado/lob/AbstractBlob.java b/src/main/java/com/amazon/carbonado/lob/AbstractBlob.java new file mode 100644 index 0000000..3da80e9 --- /dev/null +++ b/src/main/java/com/amazon/carbonado/lob/AbstractBlob.java @@ -0,0 +1,189 @@ +/*
+ * Copyright 2006 Amazon Technologies, Inc. or its affiliates.
+ * Amazon, Amazon.com and Carbonado are trademarks or registered trademarks
+ * of Amazon Technologies, Inc. or its affiliates. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.amazon.carbonado.lob;
+
+import java.io.DataOutputStream;
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.io.Reader;
+import java.io.Writer;
+
+import java.nio.charset.Charset;
+import java.nio.charset.CharsetDecoder;
+
+import com.amazon.carbonado.FetchException;
+import com.amazon.carbonado.PersistException;
+import com.amazon.carbonado.Repository;
+import com.amazon.carbonado.Transaction;
+
+/**
+ * AbstractBlob implements a small set of common Blob methods.
+ *
+ * @author Brian S O'Neill
+ */
+public abstract class AbstractBlob implements Blob {
+ private static Charset UTF_8 = Charset.forName("UTF-8");
+
+ private final Repository mRepo;
+
+ protected AbstractBlob() {
+ mRepo = null;
+ }
+
+ /**
+ * Use of this constructor indicates that setValue should operate within a
+ * transaction. A Repository is passed in for entering the transaction.
+ *
+ * @param repo optional repository to use for performing string conversion
+ * within transactions
+ */
+ protected AbstractBlob(Repository repo) {
+ mRepo = repo;
+ }
+
+ public String asString() throws FetchException {
+ return asString(UTF_8);
+ }
+
+ public String asString(String charsetName) throws FetchException {
+ return asString(Charset.forName(charsetName));
+ }
+
+ public String asString(Charset charset) throws FetchException {
+ Transaction txn = mRepo == null ? null : mRepo.enterTransaction();
+ try {
+ long length = getLength();
+
+ if (length > Integer.MAX_VALUE) {
+ throw new IllegalArgumentException
+ ("Blob is too long to fit in a String: " + length);
+ }
+
+ if (length <= 0) {
+ return "";
+ }
+
+ CharsetDecoder decoder = charset.newDecoder();
+
+ long charLength = (long) (decoder.averageCharsPerByte() * length);
+
+ if (charLength > Integer.MAX_VALUE) {
+ charLength = Integer.MAX_VALUE;
+ }
+
+ char[] buffer = new char[(int) charLength];
+
+ Reader r = new InputStreamReader(openInputStream(), decoder);
+
+ try {
+ int offset = 0;
+ int amt;
+ while ((amt = r.read(buffer, offset, buffer.length - offset)) >= 0) {
+ offset += amt;
+ if (amt == 0 && offset >= buffer.length) {
+ // Expand capacity.
+ charLength *= 2;
+ if (charLength >= Integer.MAX_VALUE) {
+ charLength = Integer.MAX_VALUE;
+ }
+ if (charLength <= buffer.length) {
+ throw new IllegalArgumentException
+ ("Blob is too long to fit in a String");
+ }
+ char[] newBuffer = new char[(int) charLength];
+ System.arraycopy(buffer, 0, newBuffer, 0, buffer.length);
+ buffer = newBuffer;
+ }
+ }
+
+ return new String(buffer, 0, offset);
+ } catch (IOException e) {
+ throw AbstractClob.toFetchException(e);
+ }
+ } finally {
+ if (txn != null) {
+ try {
+ txn.exit();
+ } catch (PersistException e) {
+ // Don't care.
+ }
+ }
+ }
+ }
+
+ public void setValue(String value) throws PersistException {
+ setValue(value, UTF_8);
+ }
+
+ public void setValue(String value, String charsetName) throws PersistException {
+ setValue(value, Charset.forName(charsetName));
+ }
+
+ public void setValue(String value, Charset charset) throws PersistException {
+ if (value == null) {
+ throw new IllegalArgumentException("Blob value cannot be null");
+ }
+
+ if (mRepo == null) {
+ setLength(0);
+ try {
+ Writer w = new OutputStreamWriter(openOutputStream(), charset);
+ w.write(value);
+ w.close();
+ } catch (IOException e) {
+ throw AbstractClob.toPersistException(e);
+ }
+ } else {
+ Transaction txn = mRepo.enterTransaction();
+ try {
+ long originalLength = getLength();
+
+ int newLength;
+ try {
+ DataOutputStream out = new DataOutputStream(openOutputStream());
+ Writer w = new OutputStreamWriter(out, charset);
+ w.write(value);
+ w.close();
+ newLength = out.size();
+ } catch (IOException e) {
+ throw AbstractClob.toPersistException(e);
+ }
+
+ if (newLength < originalLength) {
+ // Truncate.
+ setLength(newLength);
+
+ // Note: DataOutputStream counts bytes written as an int
+ // instead of a long. If String is composed of high unicode
+ // characters and encoding is UTF-8 is used, then the maximum
+ // supported String length is 715,827,882 characters. I don't
+ // expect this to be a real problem however, since the String
+ // will consume over 1.3 gigabytes of memory.
+ }
+
+ txn.commit();
+ } catch (FetchException e) {
+ throw e.toPersistException();
+ } finally {
+ txn.exit();
+ }
+ }
+ }
+}
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