3.10

所花时间：4小时

代码量：83

博客篇：1

了解到的知识点

之前一直报错，连接不上，原因是我的mysql没有远程访问权限

mysql数据库的连接：

在xml添加网络访问权限

<uses-permission android:name="android.permission.INTERNET" />
然后创建方法mymysql()
在oncreate()中调用该方法，完成数据库的访问

package com.example.myapplication;

import android.util.Log;

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

public class Dao {
    public String sel1() throws Exception {
        Connection conn = (Connection) DBHelpOpen.getConn();
        String sql1 = "select * from cal1";
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(sql1);
        String s;
        rs.next();
        s = rs.getString(2);
        stmt.close();
        conn.close();
        return s;
    }

    private static final String TAG = "mysql11111";
    java.sql.Connection conn = null;

    public static void mymysql() {
        final Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {

                while (!Thread.interrupted()) {
                    try {
                        Thread.sleep(100);  // 每隔0.1秒尝试连接
                    } catch (InterruptedException e) {
                        Log.e(TAG, e.toString());
                    }

// 1.加载JDBC驱动
                    try {
                        Class.forName("com.mysql.jdbc.Driver");
                        Log.v(TAG, "加载JDBC驱动成功");
                    } catch (ClassNotFoundException e) {
                        Log.e(TAG, "加载JDBC驱动失败");
                        return;
                    }

                    // 2.设置好IP/端口/数据库名/用户名/密码等必要的连接信息
                    String ip = "192.168.218.224";
                    int port = 3306;
                      String dbName = "db1";
                    String url = "jdbc:mysql://" + ip + ":" + port
                            + "/" + dbName+"?useUnicode=true&characterEncoding=utf-8&useSSL=false";
                    // 构建连接mysql的字符串
                    String user = "root";
                    String password = "1234";

                    String s;
                    // 3.连接JDBC
                    try {
                        java.sql.Connection conn = DriverManager.getConnection(url, user, password);
                        Log.d(TAG, "数据库连接成功");
                        String sql1 = "select * from cal1";
                        Statement stmt = conn.createStatement();
                        ResultSet rs = stmt.executeQuery(sql1);
                        rs.next();
                        s = rs.getString(2);
                        Log.d(TAG, s);
                        stmt.close();

                        conn.close();
                        return;
                    } catch (SQLException e) {
                        Log.e(TAG, e.getMessage());
                    }

                }
            }
        });
        thread.start();
    }
}