建立能以JSON檔案格式儲存的實體

    public Crime(JSONObject json) throws JSONException{
        mId = UUID.fromString(json.getString(JSON_ID));
        if(json.has(JSON_TITLE))
            mTitle = json.getString(JSON_TITLE);
        mSolved = json.getBoolean(JSON_SOLVED);
        mDate = new Date(json.getLong(JSON_DATE));
    }

    /**
     * 將Crime物件資料轉換為可寫入JSON檔案的JSONObject物件資料。
     */
 

    public JSONObject toJson() throws JSONException{
        JSONObject json = new JSONObject();
        json.put(JSON_ID, mId.toString());
        json.put(JSON_TITLE, mTitle);
        json.put(JSON_SOLVED, mSolved);
        json.put(JSON_DATE, mDate.getTime());
        return json;
    }

建立JSON檔案的儲存與讀取類

package com.huangfei.criminalintent;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Writer;
import
 
 java.util.ArrayList;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONTokener;

import android.content.Context;
/**
 * JSON檔案的儲存與讀取
 */
public class CriminalIntentJSONSerializer {
    private Context mContext;
    private String mFilename;

    public CriminalIntentJSONSerializer(Context context, String filename) {
        super();
        mContext = context;
        mFilename = filename;
    }

    /**
     * JSON檔案的讀取
     * @throws JSONException 
     */
    public ArrayList<Crime> loadCrimes() throws IOException, JSONException{
        ArrayList<Crime> crimes = new ArrayList<Crime>();
        BufferedReader reader = null;

        try {
            FileInputStream in = mContext.openFileInput(mFilename);
            reader = new BufferedReader(new InputStreamReader(in));
            StringBuilder jsonString = new StringBuilder();
            String line = null;
            while((line = reader.readLine()) != null){
                jsonString.append(line);
            }

            JSONArray array = (JSONArray) new JSONTokener(jsonString.toString()).nextValue();
            for (int i = 0; i < array.length(); i++) {
                crimes.add(new Crime(array.getJSONObject(i)));
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } finally {
            if(reader != null)
                reader.close();
        }

        return crimes;
    }

    /**
     * JSON檔案的儲存
     */
    public void saveCrimes(ArrayList<Crime> crimes) throws JSONException, IOException {
        JSONArray array = new JSONArray();
        for (Crime crime : crimes) {
            array.put(crime.toJson());
        }
        Writer writer = null;

        try {
            /**
             * Context.openFileOutput(...)方法接收檔名（不能是目錄即不能包含/）以及檔案操作模式引數，會自動將傳入的檔名附加到應用沙盒檔案
             * （每個應用的沙盒檔案目錄都是裝置/data/data/目錄的子目錄，且預設以應用包命名。如：/data/data/com.huangfei.criminalintent。
             * 只有在裝置被root了，其他應用和使用者才能隨意獲取沙盒中的檔案。）
             * 目錄路徑之後，然後在新路徑下建立並開啟檔案，等待資料寫入。
             */
            FileOutputStream out = mContext.openFileOutput(mFilename, Context.MODE_PRIVATE);
            writer = new OutputStreamWriter(out);
            writer.write(array.toString());
        } finally{
            if(writer != null)
                writer.close();
        }
    }
}

JSON檔案的讀取與儲存

        mSerializer = new CriminalIntentJSONSerializer(mAppContext, FILENAME);
        try {
            mCrimes = mSerializer.loadCrimes();
        } catch (Exception e) {
            mCrimes = new ArrayList<Crime>();
            e.printStackTrace();
        }

public boolean saveCrimes(){
        try {
            mSerializer.saveCrimes(mCrimes);
            Log.d(TAG, "crimes saved to file");
            return true;
        } catch (Exception e) {
            Log.e(TAG, "Error saving crimes: ", e);
            return false;
        } 
    }

Context類提供的基本檔案或目錄處理方法

程式碼地址