关于缓存你了解多少（二）
哈哈，按照惯例，没图说个JJ啊？
老子说，一生二，二生三，三生万物。（万物生长，哈哈）
好吧，言归正传，之前一位师兄对我说，不懂就查嘛，查不到就问嘛，问不到在“靠！"嘛，
有道理，先查，
项目中涉及到缓存，想把一个json字符串解析之后获取的url 集合缓存下来，因为SharedPreferences没有存储数组的方法所以只能将其序列化，
SharedPreferences
>1 存储字符串：
思路：根据Context获取SharedPreferences对象，利用edit()方法获取Editor对象，通过Editor对象存储key-value键值对数据
最后，通过commit()方法提交数据
如：在acitivity onCreate()方法中
sp.getString("OneBelowZero", "");//默认值不用管
sp.getBoolean("Flag", true);
>ok，有人问村一个map集合怎么办啊？ 变通一下呗！
为了代码的简洁。先创建一个工具类用于存取集合
package com.example.cacheutil.sp;
import java.util.HashMap;
import java.util.Map;
import com.example.cacheutil.MainActivity;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
public class SharedpreUtil {
private Context context;
public SharedpreUtil(Context context) {
this.context = context;
}
/**
* 保存参数
*/
public void save(String path,String girl, int age) {
SharedPreferences preference = context.getSharedPreferences(path,
Context.MODE_APPEND);// 得到SharedPreference對象对象
Editor editor = preference.edit(); // 得到edit编译器
editor.putString("girl", girl);
editor.putInt("age", age);
// 提交之后才写入xml中，不提交只是在缓存中而已
editor.commit();
}
/**
* 显示参数
*/
public Map<String, String> put() {
Map<String, String> map = new HashMap<String, String>();
SharedPreferences preference = context.getSharedPreferences(MainActivity.path,
Context.MODE_APPEND);
map.put("name", preference.getString("name", ""));
map.put("age", String.valueOf(preference.getInt("age", 0)));
return map;
}
}
======================================
相信聪明的你一定被我一语点醒你梦中情人啊！
public class MainActivity extends Activity {
private EditText OneBelowZero;
private EditText One;
public static String path="shared_file";
private SharedpreUtil perf;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
OneBelowZero = (EditText) findViewById(R.id.et_str);
One = (EditText) findViewById(R.id.et_num);
}
/**
* 1
*/
private void One(){
perf = new SharedpreUtil(this);
//启动显示参数
Map<String, String> map = new HashMap<String,String>();
map=perf.put();
OneBelowZero.setText(map.get("name"));
One.setText(map.get("age"));
}
public void save(View view){
String girl = OneBelowZero.getText().toString();
int age = Integer.valueOf(One.getText().toString());
perf.save(path, girl, age);
Toast.makeText(MainActivity.this, "保存成功", Toast.LENGTH_LONG).show();
}
}
>3.接下来我们就 二生三了 sp怎么存list呢？没有方法啊？
这就是sp的不好的地方了，做的话也可以，序列化呗，稍微麻烦点见代码：
package com.example.cacheutil.sp;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.StreamCorruptedException;
import java.util.List;
import android.util.Base64;
public class SPSceneListUtil {
// 将list集合转换成字符串 SceneList to String
public static String SceneList2String(List SceneList) throws IOException {
// 实例化一个ByteArrayOutputStream对象，用来装载压缩后的字节文件。
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
// 然后将得到的字符数据装载到ObjectOutputStream
ObjectOutputStream objectOutputStream = new ObjectOutputStream(
byteArrayOutputStream);
// writeObject 方法负责写入特定类的对象的状态，以便相应的 readObject 方法可以还原它
objectOutputStream.writeObject(SceneList);
// 最后，用Base64.encode将字节文件转换成Base64编码保存在String中
String SceneListString = new String(Base64.encode(
byteArrayOutputStream.toByteArray(), Base64.DEFAULT));
// 关闭objectOutputStream
objectOutputStream.close();
return SceneListString;
}
// 将字符串转换成list集合 String to SceneList
public static List String2SceneList(String SceneListString)
throws StreamCorruptedException, IOException,
ClassNotFoundException {
byte[] mobileBytes = Base64.decode(SceneListString.getBytes(),
Base64.DEFAULT);
ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(
mobileBytes);
ObjectInputStream objectInputStream = new ObjectInputStream(
byteArrayInputStream);
List SceneList = (List) objectInputStream.readObject();
objectInputStream.close();
return SceneList;
}
}
public class MainActivity extends Activity {
private EditText OneBelowZero;
private EditText One;
public static String path = "shared_file";
public static String path2 = "shared_file2";
private SharedpreUtil perf;
private SharedPreferences sp;
private Editor edit;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
OneBelowZero = (EditText) findViewById(R.id.et_str);
One = (EditText) findViewById(R.id.et_num);
}
/**
* 1 以下所有顺需都是 取 存 的顺序
*/
private void One() {
perf = new SharedpreUtil(this);
// 启动显示参数
Map<String, String> map = new HashMap<String, String>();
map = perf.put();
OneBelowZero.setText(map.get("name"));
One.setText(map.get("age"));
}
public void save(View view) {
String girl = OneBelowZero.getText().toString();
int age = Integer.valueOf(One.getText().toString());
perf.save(path, girl, age);
Toast.makeText(MainActivity.this, "保存成功", Toast.LENGTH_LONG).show();
}
/**
* 2
*/
public List Two() {
sp = getSharedPreferences(path2, MODE_PRIVATE);
String liststr = sp.getString(path2, "");//
List list=null;
if (!TextUtils.isEmpty(liststr)) {
try {
list = SPSceneListUtil.String2SceneList(liststr);
} catch (Exception e) {
e.printStackTrace();
}
return list;
}
return null;
}
private String save2(List list) {
sp = getSharedPreferences(path2, Context.MODE_PRIVATE);
edit = sp.edit();
String listStr = null;
try {
listStr = SPSceneListUtil.SceneList2String(list);
// 存储
edit.putString("mylistStr", listStr);
edit.commit();
} catch (IOException e) {
e.printStackTrace();
}
return listStr;
}
}
SharedPreferences sp = context.getSharedPreferences(path, Context.MODE_PRIVATE);
Editor editor = sp.edit();
editor.putString(key, mJsonArray.toString());//放你的数据
editor.commit();
取：
List<map<string, string="">> datas = new ArrayList<map<string, string="">>(); SharedPreferences sp = context.getSharedPreferences("finals", Context.MODE_PRIVATE); String result = sp.getString(key, "");import java.util.AbstractMap;
import java.util.concurrent.ConcurrentHashMap;
/**
* 存取数据
*/
public class Data {
private static AbstractMap<String, Object> mData = new ConcurrentHashMap<String, Object>();
private Data() {
}
public static void putData(String key,Object obj) {
mData.put(key, obj);
}
public static Object getData(String key) {
return mData.get(key);
}
}
最后的最后：
提供可增删改查的 缓存工具类：
BestCacheUtil：
package com.example.cacheutil;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Properties;
import java.util.Set;
import android.content.Context;
/**
* 主要用于存储简单key value键值对。提供增、删、改、查方法。 可自定义路径
* @author Administrator
*/
public class BestCacheUtil {
private static Properties properties = new Properties();
private static String filepath;
private BestCacheUtil() {
}
//文件名
public static BestCacheUtil get(Context ctx, String fileName) {
return get(ctx.getCacheDir() + "/" + fileName);
}
/**
* @param filePath
* 文件绝对路径
*/
public static BestCacheUtil get(String filePath) {
createFile(filePath);
filepath = filePath;
try {
properties.load(new FileInputStream(filepath));
return new BestCacheUtil();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
/**
* 没有就创建
* @param fileName
*/
private static void createFile(String fileName) {
File file = new File(fileName);
if (!file.exists()) {
String path = file.getAbsolutePath();
String[] sourceStrArray = path.split("/");
String dirPath = "";
for (int i = 0; i < sourceStrArray.length - 1; i++) {
if (!sourceStrArray[i].equals("")) {
dirPath += "/" + sourceStrArray[i];
}
}
new File(dirPath).mkdirs();
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 完全模仿ACache啊 嘿嘿
* @param key
* @return
*/
public String getAsString(String key) {
if (key == null) {
return null;
}
Properties props = new Properties();
try {
props.load(new FileInputStream(filepath));
String value = props.getProperty(key);
value = URLDecoder.decode(value, "utf-8");
return value;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
public int getAsInt(String key) {
String str = getAsString(key);
if (str == null)
return -9999;
return Integer.valueOf(str).intValue();
}
public boolean getAsBoolean(String key) {
String str = getAsString(key);
if (str == null)
return false;
if (str.equals("true"))
return true;
return false;
}
public long getAsLong(String key) {
String str = getAsString(key);
if (str == null)
return -9999;
return Long.valueOf(str).longValue();
}
public float getAsFloat(String key) {
String str = getAsString(key);
if (str == null)
return -9999;
return Float.valueOf(str).floatValue();
}
public double getAsDouble(String key) {
String str = getAsString(key);
if (str == null)
return -9999;
return Double.valueOf(str).doubleValue();
}
/**
* 添加 变动的是：
* @param keyname
* @param keyvalue
*/
public void put(String keyname, Object keyvalue) {
// 处理中文乱码
String value = keyvalue.toString();
try {
value = URLEncoder.encode(value, "utf-8");
} catch (UnsupportedEncodingException e1) {
e1.printStackTrace();
}
try {
OutputStream fos = new FileOutputStream(filepath);
properties.setProperty(keyname, value);
properties.store(fos, null);
} catch (IOException e) {
}
}
/**
* 更新
* @param keyname
* @param keyvalue
*/
public void update(String keyname, String keyvalue) {
try {
properties.load(new FileInputStream(filepath));
OutputStream fos = new FileOutputStream(filepath);
properties.setProperty(keyname, keyvalue);
properties.store(fos, null);
} catch (IOException e) {
}
}
/**
* 根据key删除
* @param key
*/
public void delete(String key) {
try {
FileInputStream fis = new FileInputStream(filepath);
properties.load(fis);
Map map = new HashMap();
Set keySet = properties.keySet();
for (Object object : keySet) {
String objectkey = (String) object;
String value = (String) properties.get(objectkey);
map.put(objectkey, value);
}
map.remove(key);
properties.remove(key);
Set<Map.Entry<String, String>> set = map.entrySet();
for (Entry<String, String> entry : set) {
properties.setProperty(entry.getKey(), entry.getValue());
}
FileOutputStream fos = new FileOutputStream(filepath);
properties.store(fos, "delete key:" + key);
fos.close();
fis.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
使用：：：
// 这里获取mCache对象。参数也可以为文件绝对路径，当然也可以直接传入Context和文件名。 BestCacheUtil mCache = BestCacheUtil.get("test.txt"); // 增加 mCache.put("key", "OneBelowZero"); // 更新 mCache.update("key", "帅"); // 查找，这里提供多个getAs 方法。取数据找到相应的数据类型 mCache.getAsString("key"); // 删除 mCache.delete("key");根据ACache改的哦！
另外关于三级缓存：
见：http://www.cnblogs.com/yizuochengchi2012/p/5034825.html
