Java-使用com.mysql.jdbc.Driver的Android MySQL

我正在编写一个将连接到MySQL服务器的Android应用程序.现在,我正在使用http://localhost:3306/通过XAMPP在我的计算机上测试MySQL服务器.下面的代码在严格作为Java应用程序进行测试时可以正常工作.

import java.sql.*;

public class MySQL{
  public static void main(String[] args) {
    System.out.println("MySQL Connect Example.");
    Connection conn = null;
    String url = "jdbc:mysql://localhost:3306/";
    String dbName = "database";
    String driver = "com.mysql.jdbc.Driver";
    String userName = "root"; 
    String password = "";
    try {
      Class.forName(driver).newInstance();
      conn = DriverManager.getConnection(url+dbName,userName,password);
      System.out.println("Connected to the database");
      conn.close();
      System.out.println("Disconnected from database");
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

但是,当我将其添加到Android应用程序时,出现Exception e错误.

// interact with MySQL!!!
 private View.OnClickListener onSendRequest = new View.OnClickListener() {
  @Override
  public void onClick(View v) {
   EditText username = (EditText) findViewById(R.id.Huusername);
      //    String un = " " + username.getText().toString() + " ";

      System.out.println("MySQL Connect Example.");
      Connection conn = null;
      String url = "jdbc:mysql://localhost:3306/";
      String dbName = "database";
      String driver = "com.mysql.jdbc.Driver";
      String userName = "root"; 
      String password = "";
      try {
        Class.forName(driver).newInstance();
        conn = DriverManager.getConnection(url+dbName,userName,password);
        Toast.makeText(getBaseContext(),
      "Connected to the database.", Toast.LENGTH_LONG)
      .show();
        conn.close();
        Toast.makeText(getBaseContext(),
      "Disconnected form the database.", Toast.LENGTH_LONG)
      .show();
      } catch (Exception e) {
       Toast.makeText(getBaseContext(),
      "Exception e.", Toast.LENGTH_LONG)
      .show();
        e.printStackTrace();
      }


  }
 };

在编译Android应用程序时,我在控制台中注意到以下语句：

[2011-01-26 16:05:54 - hookup]: Dxwarning: Ignoring InnerClasses attribute for an anonymous inner class
(com.mysql.jdbc.interceptors.ResultSetScannerInterceptor$1) that doesn't come with an
associated EnclosingMethod attribute. This class was probably produced by a
compiler that did not target the modern .class file format. The recommended
solution is to recompile the class from source, using an up-to-date compiler
and without specifying any "-target" type options. The consequence of ignoring
this warning is that reflective operations on this class will incorrectly
indicate that it is *not* an inner class.

我认为该语句与我得到的异常有关.有没有人与MySQL和Android合作过,可以引导我朝正确的方向发展？
谢谢

解决方法:

使用JDBC连接器mysql-connector-java-3.0.17-ga-bin.jar,目前是唯一可以使用的连接器.

还要检查您的代码,您需要为应用程序的每个活动实现一个连接池,只需添加一个私有的“ Connection”变量并在您的OnCreate方法中将其初始化,例如con = DriveManager.getConnection ……,然后使用该变量每次您需要访问MYSQL时都使用private var.

标签：exception,inner-classes,java,mysql,android
来源： https://codeday.me/bug/20191023/1913912.html