0
我正在研究修改外部MySQL數據庫的android應用程序。我知道我可以使用中間的PHP/JSON服務來做到這一點，但我寧願使用JBDC，因爲連接速度更快，我的項目老師希望我這樣做。因爲這是我的第一個應用程序，我開始使用一個簡單的按鈕和一個操作（創建一個數據庫），它實際上工作（實際上是兩個按鈕，第一個不能在skd高於9的時候工作，AsyncTask不得不爲在他們使用）：在android片段中的JDBC不工作？
package com.example.prova;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.sql.*;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button button1 = (Button) findViewById(R.id.btconn1);
final Button button2 = (Button) findViewById(R.id.btconn2);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try
{
String URL = "jdbc:mysql://" + "192.168.1.200" + ":" + "3306";
String USER = "app";
String PASS = "android";
Toast.makeText(getApplicationContext(),
"Conectando a servidor MySQL",
Toast.LENGTH_SHORT).show();
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection conn = DriverManager.getConnection(URL, USER, PASS);
Toast.makeText(getApplicationContext(),
"Conectado Servidor MySQL",
Toast.LENGTH_LONG).show();
Statement stmt = conn.createStatement();
String SQL = "CREATE DATABASE SYNC";
stmt.executeUpdate(SQL);
conn.close();
}
catch (ClassNotFoundException e)
{
Toast.makeText(getApplicationContext(),
"Error: " + e.getMessage(),
Toast.LENGTH_SHORT).show();
}
catch (SQLException e)
{
Toast.makeText(getApplicationContext(),
"Error: " + e.getMessage(),
Toast.LENGTH_SHORT).show();
}
catch (Exception e)
{
Toast.makeText(getApplicationContext(),
"Error: " + e.getMessage(),
Toast.LENGTH_LONG).show();
}
}
});
button2.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
new LED13ON().execute();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public class LED13ON extends AsyncTask<Void, Integer, Void> {
@Override
protected void onPostExecute(Void result){
SystemClock.sleep(2000);
}
@Override
protected void onPreExecute(){
SystemClock.sleep(2100);
}
@Override
protected void onProgressUpdate(Integer... values){
SystemClock.sleep(100);
}
@Override
protected Void doInBackground(Void... arg0){
try
{
String URL = "jdbc:mysql://" + "192.168.1.200" + ":" + "3306";
String USER = "app";
String PASS = "android";
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection conn = DriverManager.getConnection(URL, USER, PASS);
Statement stmt = conn.createStatement();
String SQL = "CREATE DATABASE aSYNC";
stmt.executeUpdate(SQL);
conn.close();
}
catch (ClassNotFoundException e)
{
}
catch (SQLException e)
{
}
catch (Exception e)
{
}
return null;
}
}
}
問題是，當我嘗試使用碎片，日食不返回錯誤回報，但JDBC代碼是行不通的。我知道那只是JDBC代碼不工作，因爲它進入LED13ON內部併產生SystemClock.sleep（2000），因爲該按鈕被標記了兩秒鐘。這是我對新一類片段的代碼：
package com.example.smarthome;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Locale;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.NavUtils;
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
public class Fragment_main extends Fragment {
public Fragment_main() {
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main,container, false);
Button btn = (Button) rootView.findViewById(R.id.btconn1);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick (View v) {
new LED13ON().execute();
}
});
return rootView;
}
public class LED13ON extends AsyncTask<Void, Integer, Void> {
@Override
protected void onPostExecute(Void result){
SystemClock.sleep(2000);
}
@Override
protected void onPreExecute(){
SystemClock.sleep(2100);
}
@Override
protected void onProgressUpdate(Integer... values){
SystemClock.sleep(100);
}
@Override
protected Void doInBackground(Void... arg0){
try
{
String URL = "jdbc:mysql://" + "192.168.1.200" + ":" + "3306";
String USER = "app";
String PASS = "android";
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection conn = DriverManager.getConnection(URL, USER, PASS);
Statement stmt = conn.createStatement();
String SQL = "CREATE DATABASE aSYNC";
stmt.executeUpdate(SQL);
conn.close();
}
catch (ClassNotFoundException e)
{
}
catch (SQLException e)
{
}
catch (Exception e)
{
}
return null;
}
}
}
所以我不明白爲什麼被相同的代碼它不是第二個應用程序的工作，已經改變了setOnClickListener的片段工作。誰能幫我？我真的很喜歡用我的應用程序的滑動視圖，因爲我認爲它適合更多的Android Holo風格。
謝謝你的時間！
我建議的第一件事就是記錄您發現的異常。其次，記錄不同部分的代碼，以確保它沒有到達這些部分。請注意，如果您啓動AsyncTask，則不會看到該按鈕掛起。這是一件好事。要記錄...'Log.w（「ClassName」，message）;' – JRomero
另外，爲什麼睡覺？ – JRomero