小编Gob*_*nch的帖子

我需要将使用我的应用程序拍摄的照片保存在特定文件夹中.我已经阅读了很多这个问题的解决方案,但我无法使它们中的任何一个工作,所以我寻求帮助.

MainActivity.java

public void onClick(View v) {

    Intent camera = new Intent(
            android.provider.MediaStore.ACTION_IMAGE_CAPTURE);

    //Folder is already created
    String dirName = Environment.getExternalStorageDirectory().getPath()
            + "/MyAppFolder/MyApp" + n + ".png";

    Uri uriSavedImage = Uri.fromFile(new File(dirName));
    camera.putExtra(MediaStore.EXTRA_OUTPUT, uriSavedImage);
    startActivityForResult(camera, 1);

    n++;
}

AndroidManifest.xml中

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

我db.sqlite在Asset文件夹中有我的文件,当我尝试打开它时出现此错误:

android.database.sqlite.SQLiteCantOpenDatabaseException:未知错误(代码14):无法打开数据库

我尝试了不同的路径和名称(有和没有扩展名),但我不能使它工作.

package com.example.APP.db;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;

public class DataBaseHelper extends SQLiteOpenHelper {

// The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.example.APP/databases/";
private static String DB_NAME = "app";
private SQLiteDatabase myDataBase;
private final Context myContext;

/**
 * Constructor Takes and keeps a reference of the passed context in order …

我正在使用Mosquitto和Paho的Python实现来尝试传达几个程序.当我使用最后一个功能时,我遇到了一些麻烦.我的代码是这样的:

会员键:

import paho.mqtt.client as mqtt
def on_message(client, userdata, msg):
    print 'Received: ' + msg.payload

client = mqtt.Client()
client.on_message = on_message

client.connect('localhost', 1883)
client.subscribe('hello/#')

client.loop_forever()

出版商:

import paho.mqtt.client as mqtt

client = mqtt.Client()

client.will_set('hello/will', 'Last will', 0, False)
client.connect('localhost', 1883)

client.publish('hello/world', 'Regular msg', 0, False)
client.disconnect()

输出:

Received: Last will

我应该只接收常规消息,因为我client.disconnect()用来关闭连接.如果我评论该will_set行,我会收到常规消息.我也尝试在同一主题上发布它们并且它不起作用.