java - 尝试将外部数据库 (postgreSQL) 与我的 android 应用程序连接

Question

我的 android 应用程序有问题，不知道如何解决....我正在尝试建立连接并抛出我的外部数据库(postgreSQL)并在那里获取一些信息......我在 Java 上编写了一些代码并且连接工作正常(我也能够进行一些查询并接收结果)!问题是，如果我将我在 java 类上编写的代码导入我的 android 应用程序，它会抛出一个我不理解的错误....

05-18 16:09:10.273: W/System.err(5395): org.postgresql.util.PSQLException: Something unusual has occured to cause the driver to fail. Please report this exception.
05-18 16:09:10.273: W/System.err(5395):     at org.postgresql.Driver.connect(Driver.java:287)
05-18 16:09:10.273: W/System.err(5395):     at java.sql.DriverManager.getConnection(DriverManager.java:175)
05-18 16:09:10.273: W/System.err(5395):     at java.sql.DriverManager.getConnection(DriverManager.java:209)
05-18 16:09:10.273: W/System.err(5395):     at com.mlab.android.basicoverlays.PostgreSQL.setConnection(PostgreSQL.java:55)
05-18 16:09:10.273: W/System.err(5395):     at com.mlab.android.basicoverlays.PostgreSQL.<init>(PostgreSQL.java:18)
05-18 16:09:10.273: W/System.err(5395):     at com.example.basicmaponline.MainActivity.onCreate(MainActivity.java:31)
05-18 16:09:10.273: W/System.err(5395):     at android.app.Activity.performCreate(Activity.java:5250)
05-18 16:09:10.273: W/System.err(5395):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
05-18 16:09:10.283: W/System.err(5395):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2210)
05-18 16:09:10.283: W/System.err(5395):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2296)
05-18 16:09:10.283: W/System.err(5395):     at android.app.ActivityThread.access$700(ActivityThread.java:151)
05-18 16:09:10.283: W/System.err(5395):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1281)
05-18 16:09:10.283: W/System.err(5395):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-18 16:09:10.283: W/System.err(5395):     at android.os.Looper.loop(Looper.java:137)
05-18 16:09:10.283: W/System.err(5395):     at android.app.ActivityThread.main(ActivityThread.java:5293)
05-18 16:09:10.283: W/System.err(5395):     at java.lang.reflect.Method.invokeNative(Native Method)
05-18 16:09:10.283: W/System.err(5395):     at java.lang.reflect.Method.invoke(Method.java:511)
05-18 16:09:10.283: W/System.err(5395):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
05-18 16:09:10.283: W/System.err(5395):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
05-18 16:09:10.283: W/System.err(5395):     at dalvik.system.NativeStart.main(Native Method)
05-18 16:09:10.283: W/System.err(5395): Caused by: android.os.NetworkOnMainThreadException
05-18 16:09:10.293: W/System.err(5395):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
05-18 16:09:10.293: W/System.err(5395):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
05-18 16:09:10.293: W/System.err(5395):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
05-18 16:09:10.293: W/System.err(5395):     at java.net.InetAddress.getByName(InetAddress.java:289)
05-18 16:09:10.293: W/System.err(5395):     at java.net.InetSocketAddress.<init>(InetSocketAddress.java:105)
05-18 16:09:10.293: W/System.err(5395):     at java.net.InetSocketAddress.<init>(InetSocketAddress.java:90)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.core.PGStream.<init>(PGStream.java:60)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:101)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:64)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:136)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:29)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.jdbc3g.AbstractJdbc3gConnection.<init>(AbstractJdbc3gConnection.java:21)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.jdbc4.AbstractJdbc4Connection.<init>(AbstractJdbc4Connection.java:31)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.jdbc4.Jdbc4Connection.<init>(Jdbc4Connection.java:24)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.Driver.makeConnection(Driver.java:393)
05-18 16:09:10.293: W/System.err(5395):     at org.postgresql.Driver.connect(Driver.java:267)
05-18 16:09:10.293: W/System.err(5395):     ... 19 more

P.S: 我下载了 .jar("postgresql-9.2-1002.jdbc4.jar") 扔到 postgreSQL 网站上，我把它包含在我的 android 项目中......我的 java 版本是“java 版本”1.6.0_45“.请帮助。 :/

我确实尝试过 ActiveSync 类，但它似乎不起作用，我也不知道......

//@SuppressWarnings("rawtypes")
public class loadDatabase extends AsyncTask<Void, Void, HashMap>{

    @Override
    protected HashMap doInBackground(Void... params) {
        // TODO Auto-generated method stub

        HashMap<String,SQLloja>listaLojas = new HashMap<String, SQLloja>();
    try{    
        PostgreSQL pSQL = new PostgreSQL(host,database,username,password);
        String sql = pSQL.getLojasCidadao();
        Statement st = pSQL.getConnection().createStatement();
        ResultSet rs = st.executeQuery(sql);

        while(rs.next()){
            int lcId = Integer.parseInt(rs.getString(1));
            String lcNome=rs.getString(2);
            String lcCP = rs.getString(3);
            int lcDistrito = Integer.parseInt(rs.getString(4));
            int lcConselho = Integer.parseInt(rs.getString(5));
            double lcAltitude = Double.parseDouble(rs.getString(6));
            double lcLongitude = Double.parseDouble(rs.getString(7));
            String lcTelefone = rs.getString(8);
            boolean lcEstado = Boolean.parseBoolean(rs.getString(9));
            String lcRua = rs.getString(10);

            SQLloja loja = new SQLloja(lcId,lcNome,lcCP,lcDistrito,lcConselho,lcAltitude,lcLongitude,lcTelefone,lcEstado,lcRua);

            listaLoja.put(loja.getNome(),loja.clone());

            String informacoesLoja = "Rua : "+lcRua+"\nC.P. : "+lcCP+"\nTel. : "+lcTelefone;

            Log.d("ASYNC",lcNome+" Altitude = "+lcAltitude+" Longitude = "+lcLongitude+" Rua = "+lcRua);
        }
        //listaLoja = new SQLlistLoja(listaLojas);
        rs.close();
        st.close();

    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (Exception e) {
    e.printStackTrace();
    }

    if(listaLoja!=null){
        for(SQLloja loja : listaLoja.values()){
            Log.d("ASYNC", loja.getNome() );
        }
    }
    else Log.d("ASYNC","listaLoja = null ! PQP !");


        return listaLojas;
    }

    @Override
    protected void onPostExecute(HashMap listaLojas){
        listaLoja = listaLojas;
    }
}

即使是:

if(listaLoja!=null){
        for(SQLloja loja : listaLoja.values()){
            Log.d("ASYNC", loja.getNome() );
        }
    }
    else Log.d("ASYNC","listaLoja = null ! PQP !");

它告诉我 listaLoja 可以为 null ... 通常情况下，它不应该为 null ... 由于我的 doBackground 方法(它从我的外部数据库获取信息并将它们放在我的 listaLoja ...

:/

/编辑后的帖子/

简介.java:

  public class Intro extends Activity{

//SQLlistLoja listaLoja;
HashMap<String, SQLloja> listaLoja;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.intro);
    //Intent openMainActivity = new Intent("com.example.basicmaponline.MAINACTIVITY"); //isto vem do ficheiro AndroidManifest.xml o "com.example....."
    //startActivity(openMainActivity);

    try {
        listaLoja = new loadDatabase().execute().get();
    } catch (InterruptedException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (ExecutionException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

Answer 1

当您在主 UI 线程上运行网络相关操作时发生 NetworkOnMainThread 异常。

为此你应该使用异步任务

http://developer.android.com/reference/android/os/AsyncTask.html

检查上面的链接，尤其是“4 个步骤”标题下的主题。

例子:

  class TheTask extends AsyncTask<Void,Void,Void>
  {
      protected void onPreExecute()
      {           super.onPreExecute();
                //display progressdialog.
      } 

       protected void doInBackground(Void ...params)
      {  
            //Network related opearaiton. Do not update ui here

            return null;
      } 

       protected void onPostExecute(Void result)
      {     
                super.onPostExecute(result);
                //dismiss progressdialog.
                //update ui
      } 

}

您也可以创建自己的线程。但是您需要确保在 UI 线程上更新 UI。