錯誤連接空

Question

我試圖執行下面的代碼，它通過JDBC連接我的Android應用程序到MySQL服務器：

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import java.sql.Statement; 

import android.os.Bundle; 
import android.app.Activity; 
import android.view.Menu; 
import android.widget.Toast; 
import net.sourceforge.jtds.jdbc.*; 
import net.sourceforge.jtds.jdbcx.*; 
import java.sql.*; 

public class MainActivity extends Activity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     Toast.makeText(this, "SqlConnection",Toast.LENGTH_SHORT).show(); 
     Connection conn = null; 
     try { 
      Class.forName("net.sourceforge.jtds.jdbc.Driver").newInstance(); 

      conn = DriverManager.getConnection("jdbc:jtds:sqlserver://HOSTNAME/DATABASE_NAME;user=USERNAME;password=PASSWORD;"); 
      Toast.makeText(this, "Connection Opened", Toast.LENGTH_SHORT).show(); 
      Statement stmt = conn.createStatement(); 
      ResultSet reset = stmt.executeQuery("select * from Tablename;"); 

      if(reset.next() == true){ 
       //Log.w("Data", reset.getString(1)); 
       Toast.makeText(this, reset.getString(1) , Toast.LENGTH_SHORT).show(); 
      Toast.makeText(this, "OK", Toast.LENGTH_SHORT).show(); 
      } 
       conn.close(); 
     } 
     catch (Exception e){ 
      //Log.w("Error Connection", ""+e.getMessage()); 
      Toast.makeText(this, "Error Connection" + e.getMessage(), Toast.LENGTH_SHORT).show(); 
     } 
    } 

    @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; 
    } 
} 

我已經添加了JTDS 1.2.7在我的項目，並增加了互聯網權限，結果是連接ConnectionNull

Answer 1

我相信jTDS是用來與MS SQL服務器，而不是MySQL的工作。 用於連接到MySQL，你可以使用這樣的事情：

Class.forName("com.mysql.jdbc.Driver"); 
Connection conn = null; 
conn = DriverManager.getConnection`enter code here`("jdbc:mysql://hostname:port/dbname","username", "password") 

對於使用JTDS連接到MS SQL服務器，你會做這樣的事情，與端口號和實例名：

jdbc:jtds:sqlserver://127.0.0.1:<instance_port>/Payroll