Java tutorial
/* * Copyright (C) 2010 The Android Open Source Project * * 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.android.email.service; import com.android.email.FixedLengthInputStream; import com.android.email.mail.store.imap.ImapResponse; import com.android.email.mail.store.imap.ImapResponseParser; import com.android.email.mail.store.imap.ImapString; import com.android.emailcommon.Logging; import com.android.emailcommon.TempDirectory; import com.android.emailcommon.utility.Utility; import com.android.mail.utils.LogUtils; import org.apache.commons.io.IOUtils; import java.io.ByteArrayInputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; /** * Subclass of {@link ImapString} used for literals backed by a temp file. */ public class ImapTempFileLiteral extends ImapString { /* package for test */ final File mFile; /** Size is purely for toString() */ private final int mSize; /* package */ ImapTempFileLiteral(FixedLengthInputStream stream) throws IOException { mSize = stream.getLength(); mFile = File.createTempFile("imap", ".tmp", TempDirectory.getTempDirectory()); // Unfortunately, we can't really use deleteOnExit(), because temp filenames are random // so it'd simply cause a memory leak. // deleteOnExit() simply adds filenames to a static list and the list will never shrink. // mFile.deleteOnExit(); OutputStream out = new FileOutputStream(mFile); IOUtils.copy(stream, out); out.close(); } /** * Make sure we delete the temp file. * * We should always be calling {@link ImapResponse#destroy()}, but it's here as a last resort. */ @Override protected void finalize() throws Throwable { try { destroy(); } finally { super.finalize(); } } @Override public InputStream getAsStream() { checkNotDestroyed(); try { return new FileInputStream(mFile); } catch (FileNotFoundException e) { // It's probably possible if we're low on storage and the system clears the cache dir. LogUtils.w(Logging.LOG_TAG, "ImapTempFileLiteral: Temp file not found"); // Return 0 byte stream as a dummy... return new ByteArrayInputStream(new byte[0]); } } @Override public String getString() { checkNotDestroyed(); try { byte[] bytes = IOUtils.toByteArray(getAsStream()); // Prevent crash from OOM; we've seen this, but only rarely and not reproducibly if (bytes.length > ImapResponseParser.LITERAL_KEEP_IN_MEMORY_THRESHOLD) { throw new IOException(); } return Utility.fromAscii(bytes); } catch (IOException e) { LogUtils.w(Logging.LOG_TAG, "ImapTempFileLiteral: Error while reading temp file", e); return ""; } } @Override public void destroy() { try { if (!isDestroyed() && mFile.exists()) { mFile.delete(); } } catch (RuntimeException re) { // Just log and ignore. LogUtils.w(Logging.LOG_TAG, "Failed to remove temp file: " + re.getMessage()); } super.destroy(); } @Override public String toString() { return String.format("{%d byte literal(file)}", mSize); } public boolean tempFileExistsForTest() { return mFile.exists(); } }