DbUtils介绍
Apache组织下的一个轻量级ORM框架Commons DbUtils: JDBC Utility Component
两个核心方法update方法 ==> insert，update，deletequery方法 ==> select一个核心类QueryRunner DbUtils的核心类
2 DbUtils ORM工具使用
package com.qfedu.c_dbutils;import com.qfedu.b_studentsys.entity.Student;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.*;
import org.junit.Test;
import util.JdbcUtil;import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.List;
import java.util.Map;/*** DbUtils ORM框架演示** @author Anonymous 2020/3/25 16:03*/
public class DbUtilsTest {@Testpublic void testInsert() throws SQLException {// 1. DbUtils核心类 QueryRunner对象QueryRunner runner = new QueryRunner();// 2. 插入数据到Student数据表中String sql = "insert into student(name, age, gender, score, address) value(?, ?, ?, ?, ?)";Object[] parameters = {"老黑", 70, true, 59, "河南郑州"};// 3. 获取数据库连接Connection connection = JdbcUtil.getConnection();// 4. 执行Update方法runner.update(connection, sql, parameters);JdbcUtil.close(connection);}/*** 了解操作方式， ResultSetHandler*/@Testpublic void testQuery1() throws SQLException {// 1. DbUtils核心类 QueryRunner对象QueryRunner runner = new QueryRunner();// 2. SQL语句String sql = "select * from student where id = 1";Connection connection = JdbcUtil.getConnection();/*ResultSetHandler 核心接口ResultSet结果集 Handler处理，核心方法 handler(ResultSet rs)*/Student student = runner.query(connection, sql, rs -> {Student stu = null;if (rs.next()) {int id = rs.getInt("id");String name = rs.getString("name");int age = rs.getInt("age");boolean gender = rs.getBoolean("gender");float score = rs.getFloat("score");String address = rs.getString("address");stu = new Student(id, name, age, gender, score, address);}return stu;});System.out.println(student);JdbcUtil.close(connection);}/*** BeanHandler*/@Testpublic void queryBean() throws SQLException {// 1. DbUtils核心类 QueryRunner对象QueryRunner runner = new QueryRunner();// 2. SQL语句String sql = "select * from student where id = 1";Connection connection = JdbcUtil.getConnection();/*BeanHandler: 处理符合JavaBean规范的类对象，传入参数是对应JavaBean规范 Class对象*/Student student = runner.query(connection, sql, new BeanHandler<>(Student.class));System.out.println(student);JdbcUtil.close(connection);}/*** BeanListHandler*/@Testpublic void queryBeanList() throws SQLException {// 1. DbUtils核心类 QueryRunner对象QueryRunner runner = new QueryRunner();// 2. SQL语句String sql = "select * from student where id > ?";Connection connection = JdbcUtil.getConnection();/*BeanListHandler: 处理符合JavaBean规范的实体类，并且返回值是一个List集合包含制定的JavaBean实体类*/List<Student> list = runner.query(connection, sql, new BeanListHandler<>(Student.class), 2);for (Student student : list) {System.out.println(student);}JdbcUtil.close(connection);}/*** ArrayHandler*/@Testpublic void queryArray() throws SQLException {// 1. DbUtils核心类 QueryRunner对象QueryRunner runner = new QueryRunner();// 2. SQL语句String sql = "select * from student where id = 1";Connection connection = JdbcUtil.getConnection();/*ArrayHandler: 查询一个数据行，数据行中的所有数据整合成一个Object类型数组返回*/Object[] values = runner.query(connection, sql, new ArrayHandler());System.out.println(Arrays.toString(values));JdbcUtil.close(connection);}/*** ArrayListHandler*/@Testpublic void queryArrayList() throws SQLException {// 1. DbUtils核心类 QueryRunner对象QueryRunner runner = new QueryRunner();// 2. SQL语句String sql = "select * from student where id > ?";Connection connection = JdbcUtil.getConnection();/*ArrayListHandler: 查询结果集中所有数据行，每一行数据对应一个Object类型数组，存储在List集合中*/List<Object[]> list = runner.query(connection, sql, new ArrayListHandler(), 2);for (Object[] values : list) {System.out.println(Arrays.toString(values));}JdbcUtil.close(connection);}/*** MapHandler*/@Testpublic void queryMap() throws SQLException {// 1. DbUtils核心类 QueryRunner对象QueryRunner runner = new QueryRunner();// 2. SQL语句String sql = "select * from student where id = 1";Connection connection = JdbcUtil.getConnection();/*MapHandler: 处理一个数据行，数据行中字段是对应Key，字段对应数据是value，组成一个Map双边队列*/Map<String, Object> map = runner.query(connection, sql, new MapHandler());System.out.println(map);}/*** MapListHandler*/@Testpublic void queryMapList() throws SQLException {// 1. DbUtils核心类 QueryRunner对象QueryRunner runner = new QueryRunner();// 2. SQL语句String sql = "select * from student where id > ?";Connection connection = JdbcUtil.getConnection();/*MapListHandler: 结果集中所有的数据行，每一行对应一个Map对象，字段名为Key，字段对应的数据为value，所有数据行存储在List中*/List<Map<String, Object>> mapList = runner.query(connection, sql, new MapListHandler(), 2);for (Map<String, Object> map : mapList) {System.out.println(map);}}
}
3 ResultHandler以及其子类
ResultSetHandler 核心接口ResultSet结果集 Handler处理， 核心方法 handler(ResultSet rs)BeanHandler: 处理符合JavaBean规范的类对象，传入参数是对应JavaBean规范 Class对象BeanListHandler: 处理符合JavaBean规范的实体类，并且返回值是一个List集合包含制定的JavaBean实体类ArrayHandler: 查询一个数据行，数据行中的所有数据整合成一个Object类型数组返回ArrayListHandler: 查询结果集中所有数据行，每一行数据对应一个Object类型数组，存储在List集合中MapHandler: 处理一个数据行，数据行中字段是对应Key，字段对应数据是value，组成一个Map双边队列MapListHandler: 结果集中所有的数据行，每一行对应一个Map对象，字段名为Key，字段对应的数据为value，所有数据行存储在List中
