1.JsonUtils    json和实体类之间相互转换　　　　　　随便提一下  App版本升级   github上有开源框架可以看一下VersionUpdate；

public class JsonUtils {
    /**
     * 将一个实体类转换成json字符串（对象中可以包含集合）
     */
    public static <T> String beanToJson(T t){
        Gson gson = new Gson();
        String json = gson.toJson(t);
        return json;
    }

    /**
     * 将一个json字符串，转换成一个实体类对象（可包含集合）
     */
    public static <T> T jsonToBean(String json,Class<T> tClass) throws IllegalAccessException, InstantiationException {
        Gson gson = new Gson();
        T t = tClass.newInstance();
        t = gson.fromJson(json, tClass);
        return t;
    }

    /**
     * 将json字符串转换成Json对象
     */
    public static JSONObject stringToJson(String json){
        try {
            return new JSONObject(json);
        } catch (JSONException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 将输入流转换成String字符串
     */
    public static String getString(InputStream in){
        try {
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len = -1;
            while ((len = in.read(buffer)) != -1){
                byteArrayOutputStream.write(buffer,0,len);
            }
            byte[] bytes = byteArrayOutputStream.toByteArray();
            byteArrayOutputStream.close();
            return new String(bytes,"utf-8");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "";
    }

    /**
     * 从assret文件夹中读取json文件，然后转换为json对象
     */
    public static JSONObject getJsonDataFromAssert(Context context,String jsonFileName) throws IOException, JSONException {
        JSONObject jsonObject = null;
        StringBuffer sb = new StringBuffer();
        InputStream inputStream = context.getAssets().open(jsonFileName);
        int len = -1;
        byte[] buffer = new byte[1024];
        while ((len = inputStream.read(buffer)) != -1){
            sb.append(new String(buffer,0,len,"utf-8"));
        }
        inputStream.close();
        jsonObject = new JSONObject(sb.toString());
        return jsonObject;
    }
}

2.android网络判断的Utils   是否连接无wifi

public class NetworkUtils {
    //没有网络
    public static final int NO_NETWORK = 0;
    //wifi状态
    public static final int WIFI = 1;
    //没有wifi状态
    public static final int NO_WIFI = 2;


    /**
     * 检测当前是否有网络连接
     */
    public static boolean checkNetWork(Context context){
        ConnectivityManager connectManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (connectManager == null){
            return false;
        }
        NetworkInfo networkInfo = connectManager.getActiveNetworkInfo();
        if (networkInfo == null || !networkInfo.isAvailable()){
            return false;
        }
        return true;
    }

3.sdcard状态的utils

public class SdCardState {
    /**
     * 判断sd卡显示是什么状态，不存在，移除，没挂载，正在检测，挂载（正常状态）等；
     *@return  one of {@link #MEDIA_UNKNOWN}, {@link #MEDIA_REMOVED},
     *         {@link #MEDIA_UNMOUNTED}, {@link #MEDIA_CHECKING},
     *         {@link #MEDIA_NOFS}, {@link #MEDIA_MOUNTED},
     *         {@link #MEDIA_MOUNTED_READ_ONLY}, {@link #MEDIA_SHARED},
     *         {@link #MEDIA_BAD_REMOVAL}, or {@link #MEDIA_UNMOUNTABLE}.
     */
    public static String getSdStatus(){
        return Environment.getExternalStorageState();
    }

    /**
     * 判断SD卡是否是挂载状态，是否可用
     */
    public static boolean sdAvailable(){
        return Environment.MEDIA_MOUNTED.equals(getSdStatus());
    }

    /**
     * 得到sd卡根目录的路径
     */
    public static File getRootDirectory(){
        return sdAvailable() ? Environment.getExternalStorageDirectory() : null;
    }
}

    /**
     * 判断当前的网络类型是否是WIFI
     */
    public static int checkNetWorkTypeForWifi(Context context){
        if (!checkNetWork(context)){
            return NO_NETWORK;
        }
        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (cm.getNetworkInfo(ConnectivityManager.TYPE_WIFI).isConnectedOrConnecting()){
            return WIFI;
        }
        return NO_WIFI;
    }
}

保存一下简单封装的工具类JsonUtils 、android网络判断的Utils 是否连接无wifi、sdcard状态的utils