我的Android应用程序出现问题，并且不知道如何解决它.... 我试图建立连接抛出我的外部数据库（postgreSQL）并在那里获取一些信息.... 我在java上制作了一些代码并且连接完美（我也能够做一些查询并收到结果）！问题是，如果我导入我的Android应用程序我在我的java类上创建的代码，它会抛出一个我不明白的错误....
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
我确实尝试使用ActiveSync类，但似乎它不起作用，我不知道......
//@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是可以为空的...通常情况下，它应该是不可为空的...由于我的doBackground方法（从我的外部数据库获取信息并将它们放在我的listaLoja上......
：/
/编辑帖子/
Intro.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();
}
答案 0 :(得分：1)
在主UI线程上运行网络相关操作时会发生NetworkOnMainThread异常。
你应该使用asynctask用于此目的
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。
示例：
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主题。但是您需要确保在UI线程上更新UI。
答案 1 :(得分：0)
当堆栈跟踪指示时，抛出此异常是因为您正在主UI线程上执行网络代码（与PostgreSQL交谈）。这应该在后台线程上完成，以使UI响应。
请参阅http://developer.android.com/reference/android/os/NetworkOnMainThreadException.html
答案 2 :(得分：0)
看看这个NetworkOnMainThreadException - 您正在从UI线程进行一些网络调用。从Android 4.0开始，它必须在单独的线程中执行。例如，查看this。