java反射对数据库进行增删改查

import java.lang.reflect.Field;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class GenericDAO<T> {
    private Connection connection;

    public GenericDAO(Connection connection) {
        this.connection = connection;
    }

    public void insert(T obj) throws SQLException, IllegalAccessException {
        StringBuilder sql = new StringBuilder("INSERT INTO ");
        Class<?> clazz = obj.getClass();
        Field[] fields = clazz.getDeclaredFields();
        sql.append(clazz.getSimpleName()).append(" (");

        for (Field field : fields) {
            sql.append(field.getName()).append(",");
        }
        sql.deleteCharAt(sql.length() - 1).append(") VALUES (");
        for (Field field : fields) {
            sql.append("?,");
        }
        sql.deleteCharAt(sql.length() - 1).append(")");

        try (PreparedStatement ps = connection.prepareStatement(sql.toString())) {
            int index = 1;
            for (Field field : fields) {
                field.setAccessible(true);
                ps.setObject(index++, field.get(obj));
            }
            ps.executeUpdate();
        }
    }

    public List<T> query(Class<T> clazz, String whereClause) throws SQLException, IllegalAccessException, InstantiationException {
        StringBuilder sql = new StringBuilder("SELECT * FROM ");
        sql.append(clazz.getSimpleName()).append(" WHERE ").append(whereClause);

        try (PreparedStatement ps = connection.prepareStatement(sql.toString());
             ResultSet rs = ps.executeQuery()) {
            List<T> result = new ArrayList<>();
            while (rs.next()) {
                T obj = clazz.newInstance();
                Field[] fields = clazz.getDeclaredFields();
                for (Field field : fields) {
                    field.setAccessible(true);
                    field.set(obj, rs.getObject(field.getName()));
                }
                result.add(obj);
            }
            return result;
        }
    }

    // 其他增删改查方法...
}