android中简单的db的使用

 直接上代码：

package com.xxx.xxx;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

//import com.google.gson.Gson;

import android.content.Context;
import android.content.SharedPreferences;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.BitmapFactory;
import android.os.Environment;
import android.preference.PreferenceManager;
import android.text.TextUtils;
import android.util.Log;

import com.google.gson.Gson;

import org.json.JSONObject;

public class TinyDB {

    private SharedPreferences preferences;
    private String DEFAULT_APP_IMAGEDATA_DIRECTORY;
    private String lastImagePath = "";

    public TinyDB(Context appContext) {
        preferences = PreferenceManager.getDefaultSharedPreferences(appContext);
    }


    /**
     * Decodes the Bitmap from 'path' and returns it
     * @param path image path
     * @return the Bitmap from 'path'
     */
    public Bitmap getImage(String path) {
        Bitmap bitmapFromPath = null;
        try {
            bitmapFromPath = BitmapFactory.decodeFile(path);

        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }

        return bitmapFromPath;
    }


    /**
     * Returns the String path of the last saved image
     * @return string path of the last saved image
     */
    public String getSavedImagePath() {
        return lastImagePath;
    }


    /**
     * Saves 'theBitmap' into folder 'theFolder' with the name 'theImageName'
     * @param theFolder the folder path dir you want to save it to e.g "DropBox/WorkImages"
     * @param theImageName the name you want to assign to the image file e.g "MeAtLunch.png"
     * @param theBitmap the image you want to save as a Bitmap
     * @return returns the full path(file system address) of the saved image
     */
    public String putImage(String theFolder, String theImageName, Bitmap theBitmap) {
        if (theFolder == null || theImageName == null || theBitmap == null)
            return null;

        this.DEFAULT_APP_IMAGEDATA_DIRECTORY = theFolder;
        String mFullPath = setupFullPath(theImageName);

        if (!mFullPath.equals("")) {
            lastImagePath = mFullPath;
            saveBitmap(mFullPath, theBitmap);
        }

        return mFullPath;
    }


    /**
     * Saves 'theBitmap' into 'fullPath'
     * @param fullPath full path of the image file e.g. "Images/MeAtLunch.png"
     * @param theBitmap the image you want to save as a Bitmap
     * @return true if image was saved, false otherwise
     */
    public boolean putImageWithFullPath(String fullPath, Bitmap theBitmap) {
        return !(fullPath == null || theBitmap == null) && saveBitmap(fullPath, theBitmap);
    }

    /**
     * Creates the path for the image with name 'imageName' in DEFAULT_APP.. directory
     * @param imageName name of the image
     * @return the full path of the image. If it failed to create directory, return empty string
     */
    private String setupFullPath(String imageName) {
        File mFolder = new File(Environment.getExternalStorageDirectory(), DEFAULT_APP_IMAGEDATA_DIRECTORY);

        if (isExternalStorageReadable() && isExternalStorageWritable() && !mFolder.exists()) {
            if (!mFolder.mkdirs()) {
                Log.e("ERROR", "Failed to setup folder");
                return "";
            }
        }

        return mFolder.getPath() + '/' + imageName;
    }

    /**
     * Saves the Bitmap as a PNG file at path 'fullPath'
     * @param fullPath path of the image file
     * @param bitmap the image as a Bitmap
     * @return true if it successfully saved, false otherwise
     */
    private boolean saveBitmap(String fullPath, Bitmap bitmap) {
        if (fullPath == null || bitmap == null)
            return false;

        boolean fileCreated = false;
        boolean bitmapCompressed = false;
        boolean streamClosed = false;

        File imageFile = new File(fullPath);

        if (imageFile.exists())
            if (!imageFile.delete())
                return false;

        try {
            fileCreated = imageFile.createNewFile();

        } catch (IOException e) {
            e.printStackTrace();
        }

        FileOutputStream out = null;
        try {
            out = new FileOutputStream(imageFile);
            bitmapCompressed = bitmap.compress(CompressFormat.PNG, 100, out);

        } catch (Exception e) {
            e.printStackTrace();
            bitmapCompressed = false;

        } finally {
            if (out != null) {
                try {
                    out.flush();
                    out.close();
                    streamClosed = true;

                } catch (IOException e) {
                    e.printStackTrace();
                    streamClosed = false;
                }
            }
        }

        return (fileCreated && bitmapCompressed && streamClosed);
    }

    // Getters

    /**
     * Get int value from SharedPreferences at 'key'. If key not found, return 0
     * @param key SharedPreferences key
     * @return int value at 'key' or 0 if key not found
     */
    public int getInt(String key) {
        return preferences.getInt(key, 0);
    }

    /**
     * Get parsed ArrayList of Integers from SharedPreferences at 'key'
     * @param key SharedPreferences key
     * @return ArrayList of Integers
     */
    public ArrayList<Integer> getListInt(String key) {
        String[] myList = TextUtils.split(preferences.getString(key, ""), "‚‗‚");
        ArrayList<String> arrayToList = new ArrayList<String>(Arrays.asList(myList));
        ArrayList<Integer> newList = new ArrayList<Integer>();

        for (String item : arrayToList)
            newList.add(Integer.parseInt(item));

        return newList;
    }

    /**
     * Get long value from SharedPreferences at 'key'. If key not found, return 0
     * @param key SharedPreferences key
     * @return long value at 'key' or 0 if key not found
     */
    public long getLong(String key) {
        return preferences.getLong(key, 0);
    }

    /**
     * Get float value from SharedPreferences at 'key'. If key not found, return 0
     * @param key SharedPreferences key
     * @return float value at 'key' or 0 if key not found
     */
    public float getFloat(String key) {
        return preferences.getFloat(key, 0);
    }

    /**
     * Get double value from SharedPreferences at 'key'. If exception thrown, return 0
     * @param key SharedPreferences key
     * @return double value at 'key' or 0 if exception is thrown
     */
    public double getDouble(String key) {
        String number = getString(key);

        try {
            return Double.parseDouble(number);

        } catch (NumberFormatException e) {
            return 0;
        }
    }

    /**
     * Get parsed ArrayList of Double from SharedPreferences at 'key'
     * @param key SharedPreferences key
     * @return ArrayList of Double
     */
    public ArrayList<Double> getListDouble(String key) {
        String[] myList = TextUtils.split(preferences.getString(key, ""), "‚‗‚");
        ArrayList<String> arrayToList = new ArrayList<String>(Arrays.asList(myList));
        ArrayList<Double> newList = new ArrayList<Double>();

        for (String item : arrayToList)
            newList.add(Double.parseDouble(item));

        return newList;
    }

    /**
     * Get parsed ArrayList of Integers from SharedPreferences at 'key'
     * @param key SharedPreferences key
     * @return ArrayList of Longs
     */
    public ArrayList<Long> getListLong(String key) {
        String[] myList = TextUtils.split(preferences.getString(key, ""), "‚‗‚");
        ArrayList<String> arrayToList = new ArrayList<String>(Arrays.asList(myList));
        ArrayList<Long> newList = new ArrayList<Long>();

        for (String item : arrayToList)
            newList.add(Long.parseLong(item));

        return newList;
    }

    /**
     * Get String value from SharedPreferences at 'key'. If key not found, return ""
     * @param key SharedPreferences key
     * @return String value at 'key' or "" (empty String) if key not found
     */
    public String getString(String key) {
        return preferences.getString(key, "");
    }

    /**
     * Get parsed ArrayList of String from SharedPreferences at 'key'
     * @param key SharedPreferences key
     * @return ArrayList of String
     */
    public ArrayList<String> getListString(String key) {
        return new ArrayList<String>(Arrays.asList(TextUtils.split(preferences.getString(key, ""), "‚‗‚")));
    }

    /**
     * Get boolean value from SharedPreferences at 'key'. If key not found, return false
     * @param key SharedPreferences key
     * @return boolean value at 'key' or false if key not found
     */
    public boolean getBoolean(String key) {
        return preferences.getBoolean(key, false);
    }

    /**
     * Get parsed ArrayList of Boolean from SharedPreferences at 'key'
     * @param key SharedPreferences key
     * @return ArrayList of Boolean
     */
    public ArrayList<Boolean> getListBoolean(String key) {
        ArrayList<String> myList = getListString(key);
        ArrayList<Boolean> newList = new ArrayList<Boolean>();

        for (String item : myList) {
            if (item.equals("true")) {
                newList.add(true);
            } else {
                newList.add(false);
            }
        }

        return newList;
    }

    public ArrayList<Object> getListObject(String key, Class<?> mClass){
    	Gson gson = new Gson();

    	ArrayList<String> objStrings = getListString(key);
    	ArrayList<Object> objects =  new ArrayList<Object>();

    	for(String jObjString : objStrings){
    		Object value  = gson.fromJson(jObjString,  mClass);
    		objects.add(value);
    	}
    	return objects;
    }

    public <T> T getObject(String key, Class<T> classOfT){
        String json = getString(key);
        Object value = new Gson().fromJson(json, classOfT);
        if (value == null)
            throw new NullPointerException();
        return (T)value;
    }


    // Put methods

    /**
     * Put int value into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param value int value to be added
     */
    public void putInt(String key, int value) {
        checkForNullKey(key);
        preferences.edit().putInt(key, value).apply();
    }

    /**
     * Put ArrayList of Integer into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param intList ArrayList of Integer to be added
     */
    public void putListInt(String key, ArrayList<Integer> intList) {
        checkForNullKey(key);
        Integer[] myIntList = intList.toArray(new Integer[intList.size()]);
        preferences.edit().putString(key, TextUtils.join("‚‗‚", myIntList)).apply();
    }

    /**
     * Put long value into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param value long value to be added
     */
    public void putLong(String key, long value) {
        checkForNullKey(key);
        preferences.edit().putLong(key, value).apply();
    }

    /**
     * Put ArrayList of Long into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param longList ArrayList of Long to be added
     */
    public void putListLong(String key, ArrayList<Long> longList) {
        checkForNullKey(key);
        Long[] myLongList = longList.toArray(new Long[longList.size()]);
        preferences.edit().putString(key, TextUtils.join("‚‗‚", myLongList)).apply();
    }

    /**
     * Put float value into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param value float value to be added
     */
    public void putFloat(String key, float value) {
        checkForNullKey(key);
        preferences.edit().putFloat(key, value).apply();
    }

    /**
     * Put double value into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param value double value to be added
     */
    public void putDouble(String key, double value) {
        checkForNullKey(key);
        putString(key, String.valueOf(value));
    }

    /**
     * Put ArrayList of Double into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param doubleList ArrayList of Double to be added
     */
    public void putListDouble(String key, ArrayList<Double> doubleList) {
        checkForNullKey(key);
        Double[] myDoubleList = doubleList.toArray(new Double[doubleList.size()]);
        preferences.edit().putString(key, TextUtils.join("‚‗‚", myDoubleList)).apply();
    }

    /**
     * Put String value into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param value String value to be added
     */
    public void putString(String key, String value) {
        checkForNullKey(key); checkForNullValue(value);
        preferences.edit().putString(key, value).apply();
    }

    /**
     * Put ArrayList of String into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param stringList ArrayList of String to be added
     */
    public void putListString(String key, ArrayList<String> stringList) {
        checkForNullKey(key);
        String[] myStringList = stringList.toArray(new String[stringList.size()]);
        preferences.edit().putString(key, TextUtils.join("‚‗‚", myStringList)).apply();
    }

    /**
     * Put boolean value into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param value boolean value to be added
     */
    public void putBoolean(String key, boolean value) {
        checkForNullKey(key);
        preferences.edit().putBoolean(key, value).apply();
    }

    /**
     * Put ArrayList of Boolean into SharedPreferences with 'key' and save
     * @param key SharedPreferences key
     * @param boolList ArrayList of Boolean to be added
     */
    public void putListBoolean(String key, ArrayList<Boolean> boolList) {
        checkForNullKey(key);
        ArrayList<String> newList = new ArrayList<String>();

        for (Boolean item : boolList) {
            if (item) {
                newList.add("true");
            } else {
                newList.add("false");
            }
        }

        putListString(key, newList);
    }

    /**
     * Put ObJect any type into SharedPrefrences with 'key' and save
     * @param key SharedPreferences key
     * @param obj is the Object you want to put
     */
    public void putObject(String key, Object obj){
    	checkForNullKey(key);
    	Gson gson = new Gson();
    	putString(key, gson.toJson(obj));
    }

    public void putListObject(String key, ArrayList<Object> objArray){
    	checkForNullKey(key);
    	Gson gson = new Gson();
    	ArrayList<String> objStrings = new ArrayList<String>();
    	for(Object obj : objArray){
    		objStrings.add(gson.toJson(obj));
    	}
    	putListString(key, objStrings);
    }

    /**
     * 查询这个key是否存在
     * @param key
     * @return
     */
    public boolean isKeyExists(String key){
        return  preferences.contains(key);
    }

    /**
     * Remove SharedPreferences item with 'key'
     * @param key SharedPreferences key
     */
    public void remove(String key) {
        preferences.edit().remove(key).apply();
    }

    /**
     * Delete image file at 'path'
     * @param path path of image file
     * @return true if it successfully deleted, false otherwise
     */
    public boolean deleteImage(String path) {
        return new File(path).delete();
    }

    /**
     * Clear SharedPreferences (remove everything)
     */
    public void clear() {
        preferences.edit().clear().apply();
    }

    /**
     * Retrieve all values from SharedPreferences. Do not modify collection return by method
     * @return a Map representing a list of key/value pairs from SharedPreferences
     */
    public Map<String, ?> getAll() {
        return preferences.getAll();
    }

    /**
     * Register SharedPreferences change listener
     * @param listener listener object of OnSharedPreferenceChangeListener
     */
    public void registerOnSharedPreferenceChangeListener(
            SharedPreferences.OnSharedPreferenceChangeListener listener) {

        preferences.registerOnSharedPreferenceChangeListener(listener);
    }

    /**
     * Unregister SharedPreferences change listener
     * @param listener listener object of OnSharedPreferenceChangeListener to be unregistered
     */
    public void unregisterOnSharedPreferenceChangeListener(
            SharedPreferences.OnSharedPreferenceChangeListener listener) {

        preferences.unregisterOnSharedPreferenceChangeListener(listener);
    }

    /**
     * Check if external storage is writable or not
     * @return true if writable, false otherwise
     */
    public static boolean isExternalStorageWritable() {
        return Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState());
    }

    /**
     * Check if external storage is readable or not
     * @return true if readable, false otherwise
     */
    public static boolean isExternalStorageReadable() {
        String state = Environment.getExternalStorageState();

        return Environment.MEDIA_MOUNTED.equals(state) ||
                Environment.MEDIA_MOUNTED_READ_ONLY.equals(state);
    }
    /**
     * null keys would corrupt the shared pref file and make them unreadable this is a preventive measure
     * @param key the pref key to check
     */
    private void checkForNullKey(String key){
        if (key == null){
            throw new NullPointerException();
        }
    }
    /**
     * null keys would corrupt the shared pref file and make them unreadable this is a preventive measure
     * @param value the pref value to check
     */
    private void checkForNullValue(String value){
        if (value == null){
            throw new NullPointerException();
        }
    }

    /**
     * 保存 map
     * @param key
     * @param inputMap
     */
    public void saveStringMap(String key, Map<String,Object> inputMap){
        if (preferences != null){
            JSONObject jsonObject = new JSONObject(inputMap);
            String jsonString = jsonObject.toString();
            SharedPreferences.Editor editor = preferences.edit();
            editor.remove(key).commit();
            editor.putString(key, jsonString);
            editor.commit();
        }
    }

    /**
     * 加载已保存的 map
     * @param key
     * @return
     */
    public Map<String,Object> loadStringMap(String key){
        Map<String,Object> outputMap = new HashMap<String,Object>();
        try{
            if (preferences != null){
                String jsonString = preferences.getString(key, (new JSONObject()).toString());
                JSONObject jsonObject = new JSONObject(jsonString);
                Iterator<String> keysItr = jsonObject.keys();
                while(keysItr.hasNext()) {
                    String k = keysItr.next();
                    String v = (String) jsonObject.get(k);
                    outputMap.put(k,v);
                }
            }
        }catch(Exception e){
            e.printStackTrace();
        }
        return outputMap;
    }

    public void saveMap(String key, Map<String,String> inputMap){
        if (preferences != null){
            JSONObject jsonObject = new JSONObject(inputMap);
            String jsonString = jsonObject.toString();
            SharedPreferences.Editor editor = preferences.edit();
            editor.remove(key).commit();
            editor.putString(key, jsonString);
            editor.commit();
        }
    }

    /**
     * 加载已保存的 map
     * @param key
     * @return
     */
    public Map<String,String> loadMap(String key){
        Map<String,String> outputMap = new HashMap<String,String>();
        try{
            if (preferences != null){
                String jsonString = preferences.getString(key, (new JSONObject()).toString());
                JSONObject jsonObject = new JSONObject(jsonString);
                Iterator<String> keysItr = jsonObject.keys();
                while(keysItr.hasNext()) {
                    String k = keysItr.next();
                    String v = (String) jsonObject.get(k);
                    outputMap.put(k,v);
                }
            }
        }catch(Exception e){
            e.printStackTrace();
        }
        return outputMap;
    }

}

使用：

TinyDB tinydb = new TinyDB(getApplicationContext());

tinydb.putInt("clickCount", 2);
tinydb.putFloat("xPoint", 3.6f);
tinydb.putLong("userCount", 39832L);
tinydb.putString("userName", "john");
tinydb.putBoolean("isUserMale", true);

ArrayList<String> mArray = new ArrayList<String>();
mArray.add("1");
mArray.add("2");
tinydb.putListString("MyUsers", mArray);

float f = tinydb.getFloat("xPoint");
int in = tinydb.getInt("clickCount");

ArrayList<String> mArray2;
mArray2 = tinydb.getListString("MyUsers");

// 里边的数据是否有值
if(tinydb.isKeyExists("abc") == true) {
    int c = 0;
    c = c + 1;
    tinydb.remove("abc");
}

// 根据key 获取对应的map数据
Map<String,String> mp2 = tinydb.loadMap("abc");

Map<String,String> mp = new HashMap<String,String>();
mp.put("1","a");
mp.put("2","b");
mp.put("3","c");

// 增加map进去
tinydb.saveMap("abc", mp);

 

简单的使用比较方便。