SharedPreferences儲存和讀取對象
1.首先要序列化對象(下面是序列化實體類的例子,不友善貼出實體類所有的代碼)
public class LoginResult extends BaseResult implements Serializable{
private static final long serialVersionUID = 1L;
private String mobiletoken;
2.儲存和讀取對象的封裝
public class ObjectSaveUtil {
private final static String FILENAME = "login_data_save";
private final static String KEY = "loginResult";
/**
* desc:儲存對象
* @param context
* @param key
* @param obj 要儲存的對象,隻能儲存實作了serializable的對象
* modified:
*/
public static void saveObject(Context context,Object obj){
try {
// 儲存對象
SharedPreferences.Editor sharedata = context.getSharedPreferences(FILENAME, 0).edit();
//先将序列化結果寫到byte緩存中,其實就配置設定一個記憶體空間
ByteArrayOutputStream bos=new ByteArrayOutputStream();
ObjectOutputStream os=new ObjectOutputStream(bos);
//将對象序列化寫入byte緩存
os.writeObject(obj);
//将序列化的資料轉為16進制儲存
String bytesToHexString = bytesToHexString(bos.toByteArray());
//儲存該16進制數組
sharedata.putString(KEY, bytesToHexString);
sharedata.commit();
} catch (IOException e) {
e.printStackTrace();
Log.e("", "儲存obj失敗");
}
}
/**
* desc:将數組轉為16進制
* @param bArray
* @return
* modified:
*/
public static String bytesToHexString(byte[] bArray) {
if(bArray == null){
return null;
}
if(bArray.length == 0){
return "";
}
StringBuffer sb = new StringBuffer(bArray.length);
String sTemp;
for (int i = 0; i < bArray.length; i++) {
sTemp = Integer.toHexString(0xFF & bArray[i]);
if (sTemp.length() < 2)
sb.append(0);
sb.append(sTemp.toUpperCase());
}
return sb.toString();
}
/**
* desc:擷取儲存的Object對象
* @param context
* @param key
* @return
* modified:
*/
public static Object readObject(Context context){
try {
SharedPreferences sharedata = context.getSharedPreferences(FILENAME, 0);
if (sharedata.contains(KEY)) {
String string = sharedata.getString(KEY, "");
if(TextUtils.isEmpty(string)){
return null;
}else{
//将16進制的資料轉為數組,準備反序列化
byte[] stringToBytes = StringToBytes(string);
ByteArrayInputStream bis=new ByteArrayInputStream(stringToBytes);
ObjectInputStream is=new ObjectInputStream(bis);
//傳回反序列化得到的對象
Object readObject = is.readObject();
return readObject;
}
}
} catch (StreamCorruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//所有異常傳回null
return null;
}
/**
* desc:将16進制的資料轉為數組
* <p>建立人:聶旭陽 , 2014-5-25 上午11:08:33</p>
* @param data
* @return
* modified:
*/
public static byte[] StringToBytes(String data){
String hexString=data.toUpperCase().trim();
if (hexString.length()%2!=0) {
return null;
}
byte[] retData=new byte[hexString.length()/2];
for(int i=0;i<hexString.length();i++)
{
int int_ch; // 兩位16進制數轉化後的10進制數
char hex_char1 = hexString.charAt(i); 兩位16進制數中的第一位(高位*16)
int int_ch3;
if(hex_char1 >= '0' && hex_char1 <='9')
int_ch3 = (hex_char1-48)*16; 0 的Ascll - 48
else if(hex_char1 >= 'A' && hex_char1 <='F')
int_ch3 = (hex_char1-55)*16; A 的Ascll - 65
else
return null;
i++;
char hex_char2 = hexString.charAt(i); ///兩位16進制數中的第二位(低位)
int int_ch4;
if(hex_char2 >= '0' && hex_char2 <='9')
int_ch4 = (hex_char2-48); 0 的Ascll - 48
else if(hex_char2 >= 'A' && hex_char2 <='F')
int_ch4 = hex_char2-55; A 的Ascll - 65
else
return null;
int_ch = int_ch3+int_ch4;
retData[i/2]=(byte) int_ch;//将轉化後的數放入Byte裡
}
return retData;
}
}
挺好用的,歡迎大家複制使用