4.2 基于XML配置方式 / 整合三层架构组件

三层架构 概念
界面层(User Interface layer) viewcontroller 层
业务逻辑层(Business Logic Layer)service
数据访问层(Data Access layer) dao 数据库取数据

• model 层 Student

public class StudentDaoImpl implements StudentDao {

    private JdbcTemplate jdbcTemplate;

    //注入我们的jdbctemplate对象
    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    /**
     * 数据库查询全部学生数据
     * */
    @Override
    public List<Student> queryAll() {
        //jdbctemplate 进行数据库查询 ioc容器进行装配 不要自己去实例化
        String sql = "select id,name,gender,age,class as classes from students ";
        List<Student> students = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(Student.class));
        System.out.println("studentDao"+students);
        return students;
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       https://www.springframework.org/schema/context/spring-context.xsd">

    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!--druid-->
    <bean id="druidDataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="url" value="${atguigu.url}"/>
        <property name="driverClassName" value="${atguigu.driver}"/>
        <property name="username" value="${atguigu.username}"/>
        <property name="password" value="${atguigu.password}"/>
    </bean>

    <!--jdbcTemplate-->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="druidDataSource"/>
    </bean>

    <!--dao 配置 di jdbcTemplate-->
    <bean id="studentDao" class="com.atguigu.dao.impl.StudentDaoImpl" >
        <property name="jdbcTemplate" ref="jdbcTemplate"/>
    </bean>

    <!--service 配置 di dao-->
    <bean id="studentService" class="com.atguigu.service.impl.StudentServiceImpl">
        <property name="studentDao" ref="studentDao"/>
    </bean>

    <!--controller 配置 di service-->
    <bean id="studentController" class="com.atguigu.controller.StudentController">
        <property name="studentService" ref="studentService"/>
    </bean>
</beans>

public class JdbcTemplateTest {
    public void testForJava(){
        /****
         * 1.实例化对象即可
         * 2.调用方法即可 DDL DML DCL
         * JdbcTemplate 简化数据库的crud 不提供连接池
         * DruiDataSource 负责连接的创建和数据库的创建等等
         */

        //创建一个连接池对象
        DruidDataSource druidDataSource = new DruidDataSource();
        druidDataSource.setUrl("jdbc:mysql:///studb");
        druidDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        druidDataSource.setUsername("root");
        druidDataSource.setPassword("a123456");


        JdbcTemplate jdbcTemplate = new JdbcTemplate();
        jdbcTemplate .setDataSource(druidDataSource);

        //调用的方法
//        jdbcTemplate.update()             //非查询语句
//        jdbcTemplate.queryForObject();    // 查询单个对象
//        jdbcTemplate.query();             //查询集合
    }

    /**
     * 通过ioc容器读取配置的jdbcTemplate 组件
     * 1.创建ioc容器
     * 2。获取jdbc组件
     * 3。进行数据库cur动作
     * */
    @Test
    public  void  testForIoc(){
        ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("spring_01.xml");
        System.out.println(classPathXmlApplicationContext);
        JdbcTemplate jdbcTemplate = classPathXmlApplicationContext.getBean(JdbcTemplate.class);

        String sql = "insert into students(name,gender,age,class)values(?,?,?,?)";
        int row = jdbcTemplate.update(sql,"xugougou","男","18","3年2班");
        System.out.println(row);

        String sql1 = "select * from students where id = ?";
        /**
         * sql 可以使用？
         * rowMapper 列名和属性名的映射器接口
         * object...param 可变参数占位符的值
         * 返回rowMapper 指定的对象
         * */
        Student student1 =  jdbcTemplate.queryForObject(sql1, new RowMapper<Student>() {

            @Override
            public Student mapRow(ResultSet resultSet, int i) throws SQLException {
                //写结果集 i 行数
                Student student = new Student();
                student.setId(resultSet.getInt("id"));
                student.setName(resultSet.getString("name"));
                student.setAge(resultSet.getInt("age"));
                student.setGender(resultSet.getString("gender"));
                student.setClasses(resultSet.getString("class"));

                return student;
            }

        }, 1);

        Student student2 =jdbcTemplate.queryForObject(sql1,  (resultSet,  i) -> {
                //写结果集 i 行数
                Student student = new Student();
                student.setId(resultSet.getInt("id"));
                student.setName(resultSet.getString("name"));
                student.setAge(resultSet.getInt("age"));
                student.setGender(resultSet.getString("gender"));
                student.setClasses(resultSet.getString("class"));

                return student;
            }, 1);

//        //查询所有学生数据
        String sql2 = "select id,name,age,class as classes from students";
        List<Student> studentList = jdbcTemplate.query(sql2, new BeanPropertyRowMapper<Student>(Student.class));
        //Mapped class was not specified  是BeanPropertyRowMapper的构造有问题 点进去发现 参数要传一个class类
//        List<Student> studentList = jdbcTemplate.query(sql2, new BeanPropertyRowMapper<Student>());
        System.out.println(student1);
        System.out.println(student2);
        System.out.println(studentList);
    }

    /**
     * 从ioc容器中获取controller并且调用业务 内部都是ioc容器进行组装
     * */
    @Test
    public void testQueryAll(){
        ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("spring_02.xml");
        StudentController studentController = classPathXmlApplicationContext.getBean(StudentController.class);
        studentController.findAll();

    }
}