JDBC-对任意表进行查询操作

package JDBCTest.PrepardStamentQuery;

import JDBCTest.JDBCUtils.JDBCUtils;
import JDBCTest.PreparedStatement.Customer;
import com.mysql.jdbc.Connection;

import java.lang.reflect.Field;
import java.sql.*;

public class Test {
    @org.junit.jupiter.api.Test
    public void test(){
        String sql  =  "SELECT id,NAME,email FROM customers WHERE id = ?";
        Customer instance = Test.getInstance(Customer.class, sql, 2);
        System.out.println(instance);
        String sql1 = "SELECT  id,name,date FROM `order` WHERE id= ?";
        Order instance1 = Test.getInstance(Order.class, sql1, 1);
        System.out.println(instance1);


    }
    public static <T> T getInstance(Class<T> clazz,String sql, Object ...args) {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        try {
            connection = JDBCUtils.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                preparedStatement.setObject(i+1,args[i]);
            }
            resultSet = preparedStatement.executeQuery();
            ResultSetMetaData metaData = resultSet.getMetaData();
            int columnCount = metaData.getColumnCount();
            if (resultSet.next()){
                T t = clazz.newInstance();
                for (int i = 0; i <columnCount ; i++) {
                    Object obj = resultSet.getObject(i+1);
                    String catalogName = metaData.getColumnName(i+1);
                    Field declaredField = clazz.getDeclaredField(catalogName);
                    declaredField.setAccessible(true);
                    declaredField.set(t,obj);


                }
                return t;

            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtils.closeRuscre(connection, (com.mysql.jdbc.PreparedStatement) preparedStatement,resultSet);
        }

        return null;

    }
}
数据库表格如下：

 

 create table order(

id int(10) primary key  AUTO_INCREMENT,

name varchar(20),

date date

);

insert into table order(name,date)

values("aa","2000-01-02"),

("bb","2020-02-02");

查询结果如下;