图片文字缓存(上)文字缓存

今天在做项目中用到了图片缓存的问题所以我就给这个问题总结一下和整理

接下来首先我们介绍一下文字缓存，不多说啦！看代码吧！ACache 当作工具类使用就行
package com.zhongwang.diebao.utils;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.io.Serializable;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;

import org.json.JSONArray;
import org.json.JSONObject;

import android.content.Context;

/**
*
* @Description: 文字缓存类
* @author LZ
* @2015-6-7
*
*/
public class ACache {
public static final int TIME_HOUR = 60 * 60;
public static final int TIME_DAY = TIME_HOUR * 24;
private static final int MAX_SIZE = 1000 * 1000 * 50; // 50 mb
private static final int MAX_COUNT = Integer.MAX_VALUE; // 不限制存放数据的数量
private static Map<String, ACache> mInstanceMap = new HashMap<String, ACache>();
private ACacheManager mCache;

public static ACache get(Context ctx) {
return get(ctx, "ACache");
}

public static ACache get(Context ctx, String cacheName) {
File f = new File(ctx.getCacheDir(), cacheName);
return get(f, MAX_SIZE, MAX_COUNT);
}

public static ACache get(File cacheDir) {
return get(cacheDir, MAX_SIZE, MAX_COUNT);
}

public static ACache get(Context ctx, long max_zise, int max_count) {
File f = new File(ctx.getCacheDir(), "ACache");
return get(f, max_zise, max_count);
}

public static ACache get(File cacheDir, long max_zise, int max_count) {
ACache manager = mInstanceMap.get(cacheDir.getAbsoluteFile() + myPid());
if (manager == null) {
manager = new ACache(cacheDir, max_zise, max_count);
mInstanceMap.put(cacheDir.getAbsolutePath() + myPid(), manager);
}
return manager;
}

private static String myPid() {
return "_" + android.os.Process.myPid();
}

private ACache(File cacheDir, long max_size, int max_count) {
if (!cacheDir.exists() && !cacheDir.mkdirs()) {
throw new RuntimeException("can't make dirs in "
+ cacheDir.getAbsolutePath());
}
mCache = new ACacheManager(cacheDir, max_size, max_count);
}

/**
* Provides a means to save a cached file before the data are available.
* Since writing about the file is complete, and its close method is called,
* its contents will be registered in the cache. Example of use:
*
* ACache cache = new ACache(this) try { OutputStream stream =
* cache.put("myFileName") stream.write("some bytes".getBytes()); // now
* update cache! stream.close(); } catch(FileNotFoundException e){
* e.printStackTrace() }
*/
class xFileOutputStream extends FileOutputStream {
File file;

public xFileOutputStream(File file) throws FileNotFoundException {
super(file);
this.file = file;
}

public void close() throws IOException {
super.close();
mCache.put(file);
}
}

// =======================================
// ================(一)====================
// ============ String数据 读写 ==========
// =======================================
/**
* 保存 String数据 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的String数据
*/
public void put(String key, String value) {
File file = mCache.newFile(key);
BufferedWriter out = null;
try {
out = new BufferedWriter(new FileWriter(file), 1024);
out.write(value);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (out != null) {
try {
out.flush();
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
mCache.put(file);
}
}

/**
* 保存 String数据 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的String数据
* @param saveTime
* 保存的时间，单位：秒
*/
public void put(String key, String value, int saveTime) {
put(key, Utils.newStringWithDateInfo(saveTime, value));
}

public boolean isExists(String key){
File file = mCache.get(key);
if (!file.exists())
return false;
return true;
}

/**
* 读取 String数据
*
* @param key
* @return String 数据
*/
public String getAsString(String key) {
File file = mCache.get(key);
if (!file.exists())
return null;

boolean removeFile = false;
BufferedReader in = null;
try {
in = new BufferedReader(new FileReader(file));
String readString = "";
String currentLine;
while ((currentLine = in.readLine()) != null) {
readString += currentLine;
}
if (!Utils.isDue(readString)) {
return Utils.clearDateInfo(readString);
} else {
removeFile = true;
return null;
}
} catch (IOException e) {
e.printStackTrace();
return null;
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (removeFile)
remove(key);
}
}

// =======================================
// ================(二)====================
// ============= JSONObject 数据 读写 ====
// =======================================
/**
* 保存 JSONObject数据 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的JSON数据
*/
public void put(String key, JSONObject value) {
put(key, value.toString());
}

/**
* 保存 JSONObject数据 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的JSONObject数据
* @param saveTime
* 保存的时间，单位：秒
*/
public void put(String key, JSONObject value, int saveTime) {
put(key, value.toString(), saveTime);
}

/**
* 读取JSONObject数据
*
* @param key
* @return JSONObject数据
*/
public JSONObject getAsJSONObject(String key) {
String JSONString = getAsString(key);
try {
JSONObject obj = new JSONObject(JSONString);
return obj;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

// =======================================
// ================(三)====================
// ============ JSONArray 数据 读写 ======
// =======================================
/**
* 保存 JSONArray数据 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的JSONArray数据
*/
public void put(String key, JSONArray value) {
put(key, value.toString());
}

/**
* 保存 JSONArray数据 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的JSONArray数据
* @param saveTime
* 保存的时间，单位：秒
*/
public void put(String key, JSONArray value, int saveTime) {
put(key, value.toString(), saveTime);
}

/**
* 读取JSONArray数据
*
* @param key
* @return JSONArray数据
*/
public JSONArray getAsJSONArray(String key) {
String JSONString = getAsString(key);
try {
JSONArray obj = new JSONArray(JSONString);
return obj;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

// =======================================
// ================(四)====================
// ============== byte 数据 读写 =========
// =======================================
/**
* 保存 byte数据 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的数据
*/
public void put(String key, byte[] value) {
File file = mCache.newFile(key);
FileOutputStream out = null;
try {
out = new FileOutputStream(file);
out.write(value);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (out != null) {
try {
out.flush();
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
mCache.put(file);
}
}

/**
* Cache for a stream
*
* @param key
* the file name.
* @return OutputStream stream for writing data.
* @throws FileNotFoundException
* if the file can not be created.
*/
public OutputStream put(String key) throws FileNotFoundException {
return new xFileOutputStream(mCache.newFile(key));
}

/**
*
* @param key
* the file name.
* @return (InputStream or null) stream previously saved in cache.
* @throws FileNotFoundException
* if the file can not be opened
*/
public InputStream get(String key) throws FileNotFoundException {
File file = mCache.get(key);
if (!file.exists())
return null;
return new FileInputStream(file);
}

/**
* 保存 byte数据 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的数据
* @param saveTime
* 保存的时间，单位：秒
*/
public void put(String key, byte[] value, int saveTime) {
put(key, Utils.newByteArrayWithDateInfo(saveTime, value));
}

/**
* 获取 byte 数据
*
* @param key
* @return byte 数据
*/
public byte[] getAsBinary(String key) {
RandomAccessFile RAFile = null;
boolean removeFile = false;
try {
File file = mCache.get(key);
if (!file.exists())
return null;
RAFile = new RandomAccessFile(file, "r");
byte[] byteArray = new byte[(int) RAFile.length()];
RAFile.read(byteArray);
if (!Utils.isDue(byteArray)) {
return Utils.clearDateInfo(byteArray);
} else {
removeFile = true;
return null;
}
} catch (Exception e) {
e.printStackTrace();
return null;
} finally {
if (RAFile != null) {
try {
RAFile.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (removeF
c240
ile)
remove(key);
}
}

// =======================================
// ================(五)====================
// ============= 序列化 数据 读写 ========
// =======================================
/**
* 保存 Serializable数据 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的value
*/
public void put(String key, Serializable value) {
put(key, value, -1);
}

/**
* 保存 Serializable数据到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的value
* @param saveTime
* 保存的时间，单位：秒
*/
public void put(String key, Serializable value, int saveTime) {
ByteArrayOutputStream baos = null;
ObjectOutputStream oos = null;
try {
baos = new ByteArrayOutputStream();
oos = new ObjectOutputStream(baos);
oos.writeObject(value);
byte[] data = baos.toByteArray();
if (saveTime != -1) {
put(key, data, saveTime);
} else {
put(key, data);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
oos.close();
} catch (IOException e) {
}
}
}

/**
* 读取 Serializable数据
*
* @param key
* @return Serializable 数据
*/
public Object getAsObject(String key) {
byte[] data = getAsBinary(key);
if (data != null) {
ByteArrayInputStream bais = null;
ObjectInputStream ois = null;
try {
bais = new ByteArrayInputStream(data);
ois = new ObjectInputStream(bais);
Object reObject = ois.readObject();
return reObject;
} catch (Exception e) {
e.printStackTrace();
return null;
} finally {
try {
if (bais != null)
bais.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
if (ois != null)
ois.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;

}

// =======================================
// ================(五)====================
// ============== bitmap 数据 读写========
// =======================================
/**
* 保存 bitmap 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的bitmap数据
*/
/*
* public void put(String key, Bitmap value) { put(key,
* Utils.Bitmap2Bytes(value)); }
*//**
* 保存 bitmap 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的 bitmap 数据
* @param saveTime
* 保存的时间，单位：秒
*/
/*
* public void put(String key, Bitmap value, int saveTime) { put(key,
* Utils.Bitmap2Bytes(value), saveTime); }
*/
/*
*//**
* 读取 bitmap 数据
*
* @param key
* @return bitmap 数据
*/
/*
* public Bitmap getAsBitmap(String key) { if (getAsBinary(key) == null) {
* return null; } return Utils.Bytes2Bimap(getAsBinary(key)); }
*/
/*
* // ======================================= // ============= drawable 数据
* 读写 ============= // =======================================
*//**
* 保存 drawable 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的drawable数据
*/
/*
* public void put(String key, Drawable value) { put(key,
* Utils.drawable2Bitmap(value)); }
*/

/**
* 保存 drawable 到 缓存中
*
* @param key
* 保存的key
* @param value
* 保存的 drawable 数据
* @param saveTime
* 保存的时间，单位：秒
*/
/*
* public void put(String key, Drawable value, int saveTime) { put(key,
* Utils.drawable2Bitmap(value), saveTime); }
*/

/**
* 读取 Drawable 数据
*
* @param key
* @return Drawable 数据
*/
/*
* public Drawable getAsDrawable(String key) { if (getAsBinary(key) == null)
* { return null; } return
* Utils.bitmap2Drawable(Utils.Bytes2Bimap(getAsBinary(key))); }
*/

/**
* 获取缓存文件
*
* @param key
* @return value 缓存的文件
*/
public File file(String key) {
File f = mCache.newFile(key);
if (f.exists())
return f;
return null;
}

/**
* 移除某个key
*
* @param key
* @return 是否移除成功
*/
public boolean remove(String key) {
return mCache.remove(key);
}

/**
* 清除所有数据
*/
public void clear() {
mCache.clear();
}

/**
*
* @Description: 缓存管理器
* @author 朱江宾
* @2015-6-7
*
*/
public class ACacheManager {
private final AtomicLong cacheSize;
private final AtomicInteger cacheCount;
private final long sizeLimit;
private final int countLimit;
private final Map<File, Long> lastUsageDates = Collections
.synchronizedMap(new HashMap<File, Long>());
protected File cacheDir;

private ACacheManager(File cacheDir, long sizeLimit, int countLimit) {
this.cacheDir = cacheDir;
this.sizeLimit = sizeLimit;
this.countLimit = countLimit;
cacheSize = new AtomicLong();
cacheCount = new AtomicInteger();
calculateCacheSizeAndCacheCount();
}

/**
* 计算 cacheSize和cacheCount
*/
private void calculateCacheSizeAndCacheCount() {
new Thread(new Runnable() {
@Override
public void run() {
int size = 0;
int count = 0;
File[] cachedFiles = cacheDir.listFiles();
if (cachedFiles != null) {
for (File cachedFile : cachedFiles) {
size += calculateSize(cachedFile);
count += 1;
lastUsageDates.put(cachedFile,
cachedFile.lastModified());
}
cacheSize.set(size);
cacheCount.set(count);
}
}
}).start();
}

private void put(File file) {
int curCacheCount = cacheCount.get();
while (curCacheCount + 1 > countLimit) {
long freedSize = removeNext();
cacheSize.addAndGet(-freedSize);

curCacheCount = cacheCount.addAndGet(-1);
}
cacheCount.addAndGet(1);

long valueSize = calculateSize(file);
long curCacheSize = cacheSize.get();
while (curCacheSize + valueSize > sizeLimit) {
long freedSize = removeNext();
curCacheSize = cacheSize.addAndGet(-freedSize);
}
cacheSize.addAndGet(valueSize);

Long currentTime = System.currentTimeMillis();
file.setLastModified(currentTime);
lastUsageDates.put(file, currentTime);
}

private File get(String key) {
File file = newFile(key);
Long currentTime = System.currentTimeMillis();
file.setLastModified(currentTime);
lastUsageDates.put(file, currentTime);

return file;
}

private File newFile(String key) {
return new File(cacheDir, key.hashCode() + "");
}

private boolean remove(String key) {
File image = get(key);
return image.delete();
}

private void clear() {
lastUsageDates.clear();
cacheSize.set(0);
File[] files = cacheDir.listFiles();
if (files != null) {
for (File f : files) {
f.delete();
}
}
}

/**
* 移除旧的文件
*
* @return
*/
private long removeNext() {
if (lastUsageDates.isEmpty()) {
return 0;
}

Long oldestUsage = null;
File mostLongUsedFile = null;
Set<Entry<File, Long>> entries = lastUsageDates.entrySet();
synchronized (lastUsageDates) {
for (Entry<File, Long> entry : entries) {
if (mostLongUsedFile == null) {
mostLongUsedFile = entry.getKey();
oldestUsage = entry.getValue();
} else {
Long lastValueUsage = entry.getValue();
if (lastValueUsage < oldestUsage) {
oldestUsage = lastValueUsage;
mostLongUsedFile = entry.getKey();
}
}
}
}

long fileSize = calculateSize(mostLongUsedFile);
if (mostLongUsedFile.delete()) {
lastUsageDates.remove(mostLongUsedFile);
}
return fileSize;
}

private long calculateSize(File file) {
return file.length();
}
}

/**
*
* @Description: 时间计算工具
* @author 朱江宾
* @2015-6-7
*
*/
private static class Utils {

/**
* 判断缓存的String数据是否到期
*
* @param str
* @return true：到期了 false：还没有到期
*/
private static boolean isDue(String str) {
return isDue(str.getBytes());
}

/**
* 判断缓存的byte数据是否到期
*
* @param data
* @return true：到期了 false：还没有到期
*/
private static boolean isDue(byte[] data) {
String[] strs = getDateInfoFromDate(data);
if (strs != null && strs.length == 2) {
String saveTimeStr = strs[0];
while (saveTimeStr.startsWith("0")) {
saveTimeStr = saveTimeStr
.substring(1, saveTimeStr.length());
}
long saveTime = Long.valueOf(saveTimeStr);
long deleteAfter = Long.valueOf(strs[1]);
if (System.currentTimeMillis() > saveTime + deleteAfter * 1000) {
return true;
}
}
return false;
}

private static String newStringWithDateInfo(int second, String strInfo) {
return createDateInfo(second) + strInfo;
}

private static byte[] newByteArrayWithDateInfo(int second, byte[] data2) {
byte[] data1 = createDateInfo(second).getBytes();
byte[] retdata = new byte[data1.length + data2.length];
System.arraycopy(data1, 0, retdata, 0, data1.length);
System.arraycopy(data2, 0, retdata, data1.length, data2.length);
return retdata;
}

private static String clearDateInfo(String strInfo) {
if (strInfo != null && hasDateInfo(strInfo.getBytes())) {
strInfo = strInfo.substring(strInfo.indexOf(mSeparator) + 1,
strInfo.length());
}
return strInfo;
}

private static byte[] clearDateInfo(byte[] data) {
if (hasDateInfo(data)) {
return copyOfRange(data, indexOf(data, mSeparator) + 1,
data.length);
}
return data;
}

private static boolean hasDateInfo(byte[] data) {
return data != null && data.length > 15 && data[13] == '-'
&& indexOf(data, mSeparator) > 14;
}

private static String[] getDateInfoFromDate(byte[] data) {
if (hasDateInfo(data)) {
String saveDate = new String(copyOfRange(data, 0, 13));
String deleteAfter = new String(copyOfRange(data, 14,
indexOf(data, mSeparator)));
return new String[] { saveDate, deleteAfter };
}
return null;
}

private static int indexOf(byte[] data, char c) {
for (int i = 0; i < data.length; i++) {
if (data[i] == c) {
return i;
}
}
return -1;
}

private static byte[] copyOfRange(byte[] original, int from, int to) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
byte[] copy = new byte[newLength];
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}

private static final char mSeparator = ' ';

private static String createDateInfo(int second) {
String currentTime = System.currentTimeMillis() + "";
while (currentTime.length() < 13) {
currentTime = "0" + currentTime;
}
return currentTime + "-" + second + mSeparator;
}
}
}

接下来介绍一下怎么调用这个类

首先我们进行实力

aCache = ACache.get(getApplicationContext());

我们用的时候进行判断就行MyBaseApplication单例管理类

try {
if (!MyBaseApplication.aCache.isExists(docid + "")) {

//数据源是我们网络请求之后的数据进行添加MyBaseApplication.aCache.put(docid + "", dbDetial);这个方法是进行添加缓存数据
httpData();
Log.i("TAG", "HTTP");
} else {
dbDetial = (DbDetial) MyBaseApplication.aCache
.getAsObject(docid + "");

//进行读取已经缓存数据
initWebView();
Log.i("TAG", "LOCAL");
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

//进行读取数据

private void initWebView() throws FileNotFoundException {

webView.loadDataWithBaseURL(
null,
"<html><head>" + dbDetial.getTitle() + "<br>"
+ dbDetial.getDate() + "</head><br><body>"
+ dbDetial.getContent() + "<body> </html>",
"text/html", "UTF-8", null);
WebSettings settings = webView.getSettings();
settings.setTextSize(TextSize.LARGER);
// 设置此属性,可任意比例缩放
settings.setUseWideViewPort(true);
// 使之充满全屏
settings.setLoadWithOverviewMode(true);
// 设置默认编码方式
settings.setDefaultTextEncodingName("UTF-8");
// 支持JavaScript
settings.setJavaScriptEnabled(true);
// 图片过大时自动适应屏幕,缩放排版
settings.setLayoutAlgorithm(LayoutAlgorithm.SINGLE_COLUMN);
// 获取的ZoomControl的位置
settings.setBuiltInZoomControls(true);
// 允许缩放
settings.setSupportZoom(true); // 可以缩放
}

以上就是文字缓存的用法大家如何喜欢可以简介一下