JDBC DDL DML 代码片段

package io.github.jast90.jdbc.usage;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.SQLSyntaxErrorException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

/**
 * @Description: JDBC 基本使用
 * @date 2021/12/9 10:49
 */
public class Basic {
    final static String url = "jdbc:mysql://192.168.56.102:3306/jdbc";
    final static String username = "root";
    final static String password = "123456";

    static {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) throws SQLException {
//        createTable();
//        dropTable();
//        insert();
        query();
//        showCreateTable();
//        alterTable();

    }

    public static boolean createTable() {
        String sql = "create table post(id int not null primary key auto_increment,title varchar(128)) engine InnoDB character set utf8";
        return doExecute(sql,"createTable");
    }

    private static boolean doExecute(String sql,String action){
        boolean result = false;
        try {
            Connection connection = DriverManager.getConnection(url, username, password);
            Statement statement = connection.createStatement();
            statement.executeUpdate(sql);
            result = true;
        } catch (SQLSyntaxErrorException throwables) {
            throwables.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        if(result){
            System.out.println(String.format("%s table success",action));
        }
        return result;
    }

    public static boolean alterTable(){
        String sql = "alter table post add (`desc` varchar(128) not null)";
        return doExecute(sql,"alterTable");
    }

    public static void showCreateTable(){
        try {
            String sql = "show create table post";
            Connection connection = DriverManager.getConnection(url, username, password);
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery(sql);
            while (resultSet.next()){
                System.out.println(resultSet.getString(1));
                System.out.println(resultSet.getString(2));
            }
        }catch (Exception e){

        }
    }

    public static boolean dropTable() throws SQLException {
        boolean result = false;
        try {
            String sql = "drop table post";
            Connection connection = DriverManager.getConnection(url, username, password);
            Statement statement = connection.createStatement();
            statement.executeUpdate(sql);
            result = true;
        } catch (SQLSyntaxErrorException throwables) {
            throwables.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        if(result){
            System.out.println("drop table success");
        }
        return result;
    }

    public static boolean insert() throws SQLException {
        String sql = "insert into post(title,`desc`) values(?,?)";
        Connection connection = DriverManager.getConnection(url, username, password);
        PreparedStatement preparedStatement = connection.prepareStatement(sql);
        preparedStatement.setString(1,"Mybatis.");
        preparedStatement.setString(2,"Mybatis.");
        if(preparedStatement.executeUpdate() == 1){
            System.out.println("插入数据成功");
            return true;
        }
        return false;
    }

    public static void query(){
        String sql = "select id,title from post";
        List<Post> posts = doQuery(sql, Post.class);
        System.out.println(posts);
    }

    private static <T> List<T> doQuery(String sql,Class<T> tClass,Object... param){
        List<T> list = new ArrayList<>(0);
        //获取查询sql字段
        List<String> columns = ReflectUtil.columns(sql);
        try {
            Connection connection = DriverManager.getConnection(url, username, password);
            PreparedStatement preparedStatement = connection.prepareStatement(sql);
            //填充参数
            ReflectUtil.fillParams(preparedStatement,param);

            ResultSet resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
                T t = tClass.newInstance();
                for (String column : columns) {
                    //字段赋值
                    ReflectUtil.setFieldValue(t,resultSet,column,columns.indexOf(column)+1,tClass);
                }
                list.add(t);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return list;
    }

}

参考

• github