android连接mysql

导入Mysql的jar，和rxjava

    implementation "io.reactivex.rxjava2:rxjava:2.2.10"
    implementation "io.reactivex.rxjava2:rxandroid:2.0.2"

创建DBOpenHelper

package com.example.connectmysql;

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

public class DBOpenHelper {
    private static String diver = "com.mysql.jdbc.Driver";
    //加入utf-8是为了后面往表中输入中文，表中不会出现乱码的情况
    private static String url = "jdbc:mysql://ip:port/your db's name?characterEncoding=utf-8";
    private static String user = "user";//用户名
    private static String password = "password";//密码
    /*
     * 连接数据库
     * */
    public static Connection getConn(){
        Connection conn = null;
        try {
            Class.forName(diver);
            conn = (Connection) DriverManager.getConnection(url,user,password);//获取连接
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
}

创建bean类

package com.example.connectmysql;

public class StudentBean {
  String name;
  int id;
  int age;
  String major;

    public String getName() {
        return name;
    }

    public int getId() {
        return id;
    }

    public int getAge() {
        return age;
    }

    public String getMajor() {
        return major;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public void setMajor(String major) {
        this.major = major;
    }
}

在MainActivity中加入

private void executeAsyncTask(int i) {
        //Observable#create方法创建一个异步任务
        Observable.create(new ObservableOnSubscribe<Integer>() {
                    @Override
                    public void subscribe(@NonNull ObservableEmitter<Integer> e) throws Exception {

                        new Thread(new Runnable() {
                            @Override
                            public void run() {
                                Connection conn =(Connection) DBOpenHelper.getConn();
                                Statement st = null;
                                try {st = (Statement) conn.createStatement();} catch (SQLException ex) {ex.printStackTrace();}
                                switch (i){
                                    case 1:
                                        String sql = "select * from student";
                                        try {
                                            ResultSet rs = st.executeQuery(sql);
                                            while (rs.next()){
                                                studentBean=new StudentBean();
                                                studentBean.setName(rs.getString("name"));
                                                studentBean.setId(rs.getInt("id"));
                                                studentBean.setAge(rs.getInt("age"));
                                                studentBean.setMajor(rs.getString("major"));
                                                e.onNext(0);
                                            }
                                            st.close();
                                            conn.close();
                                        } catch (SQLException e) {
                                            e.printStackTrace();
                                        }
                                        break;
                                    case 2:
                                        String sqlInsert = "insert into student (id,name,age,major) values (?,?, ?,?)";
                                        try {
                                            PreparedStatement ps = conn.prepareStatement(sqlInsert);
                                            ps.setInt(1,202121103);
                                            ps.setString(2,"names");
                                            ps.setInt(3, 19);
                                            ps.setString(4,"cs");
                                            ps.executeUpdate();
                                            st.close();
                                            conn.close();
                                        } catch (SQLException e) {
                                            e.printStackTrace();
                                            Log.e("-->",e.getMessage());
                                        }
                                        e.onComplete();
                                        break;
                                    case 3:
                                        String sqlDele = "delete from student where id = ?";
                                        try {
                                            PreparedStatement ps = conn.prepareStatement(sqlDele);
                                            ps.setInt(1,202121101);
                                            ps.executeUpdate();
                                            st.close();
                                            conn.close();
                                        } catch (SQLException e) {
                                            e.printStackTrace();
                                            Log.e("-->",e.getMessage());
                                        }
                                        e.onComplete();
                                        break;
                                    case 4:
                                        String sqlUpdate = "update student set age = ? where id = ?";
                                        try {
                                            PreparedStatement ps = conn.prepareStatement(sqlUpdate);
                                            ps.setInt(1,22);
                                            ps.setInt(2,202120100);
                                            ps.executeUpdate();
                                            st.close();
                                            conn.close();
                                        } catch (SQLException e) {
                                            e.printStackTrace();
                                            Log.e("-->",e.getMessage());
                                        }
                                        e.onComplete();
                                        break;
                                }

                            }
                        }).start();
                    }
                })
                .subscribe(new Observer<Integer>() {
                    @Override
                    public void onSubscribe(@NonNull Disposable d) {
                    }

                    @Override
                    public void onNext(@NonNull Integer integer) {
                        Log.e("-->",studentBean.getName()+"\n"
                        +studentBean.getId()+"\n"
                        +studentBean.getAge()+"\n"
                        +studentBean.getMajor());
                    }

                    @Override
                    public void one rror(@NonNull Throwable e) {
                    }

                    @Override
                    public void onComplete() {
                        Log.e("-->","COMP");

                    }
                });

    }

直接用mysql语句即可