/*
* Copyright (c) 2014, Android Open Source Project,张涛.
*
* 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 org.kymjs.kjframe.http;
import android.os.SystemClock;
import org.kymjs.kjframe.utils.FileUtils;
import org.kymjs.kjframe.utils.KJLoger;
import java.io.BufferedInputStream;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* 缓存器实现类，磁盘缓存器
*/
public class DiskCache implements Cache {
private final Map<String, CacheHeader> mEntries = new LinkedHashMap<String, CacheHeader>(
16, .75f, true);
private long mTotalSize = 0; // 已使用的空间 :byte
private final File mRootDirectory; // cache路径
private final int mMaxCacheSizeInBytes; // 磁盘缓存大小
private static final float HYSTERESIS_FACTOR = 0.9f; // 缓存最大值警戒线
private static final int CACHE_MAGIC = 0x20150423;
/**
* @param rootDirectory 缓存文件夹
* @param maxCacheSizeInBytes 缓存大小
*/
public DiskCache(File rootDirectory, int maxCacheSizeInBytes) {
mRootDirectory = rootDirectory;
mMaxCacheSizeInBytes = maxCacheSizeInBytes;
}
/**
* 使用默认缓存大小(5MB)构造磁盘缓存器
*
* @param rootDirectory The root directory of the cache.
*/
public DiskCache(File rootDirectory) {
this(rootDirectory, 5 * 1024 * 1024);
}
/**
* 清空磁盘缓存
*/
@Override
public synchronized void clean() {
File[] files = mRootDirectory.listFiles();
if (files != null) {
for (File file : files) {
file.delete();
}
}
mEntries.clear();
mTotalSize = 0;
KJLoger.debug("disk Cache cleared.");
}
/**
* 获取一个cache
*
* @return 如果不存在返回null
*/
@Override
public synchronized Entry get(String key) {
CacheHeader entry = mEntries.get(key);
if (entry == null) {
return null;
}
File file = getFileForKey(key);
CountingInputStream cis = null;
try {
cis = new CountingInputStream(new FileInputStream(file));
CacheHeader.readHeader(cis); // eat header
byte[] data = streamToBytes(cis,
(int) (file.length() - cis.bytesRead));
return entry.toCacheEntry(data);
} catch (IOException e) {
KJLoger.debug("%s: %s", file.getAbsolutePath(), e.toString());
remove(key);
return null;
} finally {
if (cis != null) {
try {
cis.close();
} catch (IOException ioe) {
return null;
}
}
}
}
@Override
public synchronized void initialize() {
if (!mRootDirectory.exists()) {
if (!mRootDirectory.mkdirs()) {
KJLoger.debug("Unable to create cache dir %s",
mRootDirectory.getAbsolutePath());
}
return;
}
File[] files = mRootDirectory.listFiles();
if (files == null) {
return;
}
for (File file : files) {
BufferedInputStream fis = null;
try {
fis = new BufferedInputStream(new FileInputStream(file));
CacheHeader entry = CacheHeader.readHeader(fis);
entry.size = file.length();
putEntry(entry.key, entry);
} catch (IOException e) {
if (file != null) {
file.delete();
}
} finally {
try {
if (fis != null) {
fis.close();
}
} catch (IOException ignored) {
}
}
}
}
/**
* 刷新缓存
*
* @param key
* @param fullExpire True to fully expire the entry, false to soft expire
*/
@Override
public synchronized void invalidate(String key, boolean fullExpire) {
Entry entry = get(key);
if (entry != null && fullExpire) {
entry.ttl = 0;
put(key, entry);
}
}
@Override
public synchronized void put(String key, Entry entry) {
pruneIfNeeded(entry.data.length);
File file = getFileForKey(key);
FileOutputStream fos = null;
try {
fos = new FileOutputStream(file);
CacheHeader e = new CacheHeader(key, entry);
boolean success = e.writeHeader(fos);
if (!success) {
KJLoger.debug("Failed to write header for %s",
file.getAbsolutePath());
throw new IOException();
}
fos.write(entry.data);
putEntry(key, e);
return;
} catch (IOException e) {
FileUtils.closeIO(fos);
}
boolean deleted = file.delete();
if (!deleted) {
KJLoger.debug("Could not clean up file %s", file.getAbsolutePath());
}
}
@Override
public synchronized void remove(String key) {
boolean deleted = getFileForKey(key).delete();
removeEntry(key);
if (!deleted) {
KJLoger.debug(
"Could not delete cache entry for key=%s, filename=%s",
key, getFilenameForKey(key));
}
}
/**
* Creates a pseudo-unique filename for the specified cache key.
*
* @param key The key to generate a file name for.
* @return A pseudo-unique filename.
*/
private String getFilenameForKey(String key) {
int firstHalfLength = key.length() / 2;
String localFilename = String.valueOf(key.substring(0, firstHalfLength)
.hashCode());
localFilename += String.valueOf(key.substring(firstHalfLength)
.hashCode());
return localFilename;
}
/**
* Returns a file object for the given cache key.
*/
public File getFileForKey(String key) {
return new File(mRootDirectory, getFilenameForKey(key));
}
/**
* Prunes the cache to fit the amount of bytes specified.
*
* @param neededSpace The amount of bytes we are trying to fit into the cache.
*/
private void pruneIfNeeded(int neededSpace) {
if ((mTotalSize + neededSpace) < mMaxCacheSizeInBytes) {
return;
}
if (HttpConfig.DEBUG) {
KJLoger.debug("Pruning old cache entries.");
}
long before = mTotalSize;
int prunedFiles = 0;
long startTime = SystemClock.elapsedRealtime();
Iterator<Map.Entry<String, CacheHeader>> iterator = mEntries.entrySet()
.iterator();
while (iterator.hasNext()) {
Map.Entry<String, CacheHeader> entry = iterator.next();
CacheHeader e = entry.getValue();
boolean deleted = getFileForKey(e.key).delete();
if (deleted) {
mTotalSize -= e.size;
} else {
KJLoger.debug(
"Could not delete cache entry for key=%s, filename=%s",
e.key, getFilenameForKey(e.key));
}
iterator.remove();
prunedFiles++;
if ((mTotalSize + neededSpace) < mMaxCacheSizeInBytes
* HYSTERESIS_FACTOR) {
break;
}
}
if (HttpConfig.DEBUG) {
KJLoger.debug("pruned %d files, %d bytes, %d ms", prunedFiles,
(mTotalSize - before), SystemClock.elapsedRealtime()
- startTime);
}
}
/**
* Puts the entry with the specified key into the cache.
*
* @param key The key to identify the entry by.
* @param entry The entry to cache.
*/
private void putEntry(String key, CacheHeader entry) {
if (!mEntries.containsKey(key)) {
mTotalSize += entry.size;
} else {
CacheHeader oldEntry = mEntries.get(key);
mTotalSize += (entry.size - oldEntry.size);
}
mEntries.put(key, entry);
}
/**
* Removes the entry identified by 'key' from the cache.
*/
private void removeEntry(String key) {
CacheHeader entry = mEntries.get(key);
if (entry != null) {
mTotalSize -= entry.size;
mEntries.remove(key);
}
}
/**
* Reads the contents of an InputStream into a byte[].
*/
private static byte[] streamToBytes(InputStream in, int length)
throws IOException {
byte[] bytes = new byte[length];
int count;
int pos = 0;
while (pos < length
&& ((count = in.read(bytes, pos, length - pos)) != -1)) {
pos += count;
}
if (pos != length) {
throw new IOException("Expected " + length + " bytes, read " + pos
+ " bytes");
}
return bytes;
}
/**
* Handles holding onto the cache headers for an entry.
*/
static class CacheHeader {
public long size; // 缓存头大小
public String key;
public String etag;
public long serverDate;
public long ttl;
public long softTtl;
public Map<String, String> responseHeaders;
private CacheHeader() {
}
public CacheHeader(String key, Entry entry) {
this.key = key;
this.size = entry.data.length;
this.etag = entry.etag;
this.serverDate = entry.serverDate;
this.ttl = entry.ttl;
this.responseHeaders = entry.responseHeaders;
}
/**
* Reads the header off of an InputStream and returns a CacheHeader
* object.
*
* @param is The InputStream to read from.
* @throws IOException
*/
public static CacheHeader readHeader(InputStream is) throws IOException {
CacheHeader entry = new CacheHeader();
int magic = readInt(is);
if (magic != CACHE_MAGIC) {
// don't bother deleting, it'll get pruned eventually
throw new IOException();
}
entry.key = readString(is);
entry.etag = readString(is);
if (entry.etag.equals("")) {
entry.etag = null;
}
entry.serverDate = readLong(is);
entry.ttl = readLong(is);
entry.softTtl = readLong(is);
entry.responseHeaders = readStringStringMap(is);
return entry;
}
/**
* Creates a cache entry for the specified data.
*/
public Entry toCacheEntry(byte[] data) {
Entry e = new Entry();
e.data = data;
e.etag = etag;
e.serverDate = serverDate;
e.ttl = ttl;
e.responseHeaders = responseHeaders;
return e;
}
/**
* Writes the contents of this CacheHeader to the specified
* OutputStream.
*/
public boolean writeHeader(OutputStream os) {
try {
writeInt(os, CACHE_MAGIC);
writeString(os, key);
writeString(os, etag == null ? "" : etag);
writeLong(os, serverDate);
writeLong(os, ttl);
writeLong(os, softTtl);
writeStringStringMap(responseHeaders, os);
os.flush();
return true;
} catch (IOException e) {
KJLoger.debug("%s", e.toString());
return false;
}
}
}
private static class CountingInputStream extends FilterInputStream {
private int bytesRead = 0;
private CountingInputStream(InputStream in) {
super(in);
}
@Override
public int read() throws IOException {
int result = super.read();
if (result != -1) {
bytesRead++;
}
return result;
}
@Override
public int read(byte[] buffer, int offset, int count)
throws IOException {
int result = super.read(buffer, offset, count);
if (result != -1) {
bytesRead += result;
}
return result;
}
}
private static int read(InputStream is) throws IOException {
int b = is.read();
if (b == -1) {
throw new EOFException();
}
return b;
}
static void writeInt(OutputStream os, int n) throws IOException {
os.write((n >> 0) & 0xff);
os.write((n >> 8) & 0xff);
os.write((n >> 16) & 0xff);
os.write((n >> 24) & 0xff);
}
static int readInt(InputStream is) throws IOException {
int n = 0;
n |= (read(is) << 0);
n |= (read(is) << 8);
n |= (read(is) << 16);
n |= (read(is) << 24);
return n;
}
static void writeLong(OutputStream os, long n) throws IOException {
os.write((byte) (n >>> 0));
os.write((byte) (n >>> 8));
os.write((byte) (n >>> 16));
os.write((byte) (n >>> 24));
os.write((byte) (n >>> 32));
os.write((byte) (n >>> 40));
os.write((byte) (n >>> 48));
os.write((byte) (n >>> 56));
}
static long readLong(InputStream is) throws IOException {
long n = 0;
n |= ((read(is) & 0xFFL) << 0);
n |= ((read(is) & 0xFFL) << 8);
n |= ((read(is) & 0xFFL) << 16);
n |= ((read(is) & 0xFFL) << 24);
n |= ((read(is) & 0xFFL) << 32);
n |= ((read(is) & 0xFFL) << 40);
n |= ((read(is) & 0xFFL) << 48);
n |= ((read(is) & 0xFFL) << 56);
return n;
}
static void writeString(OutputStream os, String s) throws IOException {
byte[] b = s.getBytes("UTF-8");
writeLong(os, b.length);
os.write(b, 0, b.length);
}
static String readString(InputStream is) throws IOException {
int n = (int) readLong(is);
byte[] b = streamToBytes(is, n);
return new String(b, "UTF-8");
}
static void writeStringStringMap(Map<String, String> map, OutputStream os)
throws IOException {
if (map != null) {
writeInt(os, map.size());
for (Map.Entry<String, String> entry : map.entrySet()) {
writeString(os, entry.getKey());
writeString(os, entry.getValue());
}
} else {
writeInt(os, 0);
}
}
static Map<String, String> readStringStringMap(InputStream is)
throws IOException {
int size = readInt(is);
Map<String, String> result = (size == 0) ? Collections.<String, String>emptyMap() : new
HashMap<String, String>(size);
for (int i = 0; i < size; i++) {
String key = readString(is).intern();
String value = readString(is).intern();
result.put(key, value);
}
return result;
}
}
