What to do if Android cannot connect to mysql

Solution to the problem that Android cannot connect to mysql: First, customize the listening event in Activivty; then open up a child thread in the custom listening event; finally, change the definition of coonection to "DriverManager.getConnection(... )".

Recommendation: "mysql video tutorial"

Android Studio connects to MySQL: Problem solved: The virtual machine cannot connect to the local SQL, coon is always empty

Connect to the database in a child thread

First customize the listening event in Activivty

//写在Activity中
private Button mBtn;
  @Override
 protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        SetListener();//自定义监听事件
        }

Open a child thread in the custom listening event , pay attention to the last .start()

private void SetListener()
    {
        mBtnadmin.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View view) {
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        Connection conn=null;//创建连接
                        Statement stmt=null;//用以执行SQL语句
                        try{
                        //注册驱动
                            Class.forName("com.mysql.jdbc.Driver");
                        //数据库的执行语句
                            String sql="insert into demo values(6666,6666)";
 //获取connection对象，这里使用localhost如果无法成功，则改成10.0.2.2,这是虚拟机上电脑的地址，注意是虚拟机，用于虚拟机的测试
                            conn=DriverManager.getConnection("jdbc:mysql://10.0.2.2:3306/logindata","root","666666");
                            stmt=conn.createStatement();
                            stmt.executeUpdate(sql);
                            }
                        }catch (Exception e)
                        {
                            e.printStackTrace();
                        }finally {
                     stmt.close();
                     conn.close();
                           // JDBCUtils .Close(stmt,conn);
                        }
                    }
                }).start();
             }
        });
    }

Because I have been using a virtual machine for testing, the definition of coonection has always been

 conn= DriverManager.getConnection("jdbc:mysql://localhost/logindata","root","666666");

Every time the connection result is reported: coon=null, Finally, multiple debugging parties discovered this problem. The IP address of the computer corresponding to the virtual machine should be 10.0.2.2. That is, changing the definition of coonection to

conn= DriverManager.getConnection("jdbc:mysql://10.0.2.2:3306/logindata","root","666666");

was successful! I was always worried that it was a code problem, so I didn’t try to connect to MySQL on the server. Now I can try it!

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