spring（三）

原教程： https://www.w3cschool.cn/wkspring/

spring JDBC框架

以查询student表为例

• 创建StudentDao接口，封装有关数据库的操作（增删改查以及设置DataSource）【此处DataSource是依赖注入的】
• 创建spring bean类（Student）
• 创建实现了RowMapper接口的Mapper类（StudentMapper），用于查询对象或者对象数组
• 创建实现了DAO接口的JDBCTemplate类（StudentJDBCTemplate）（包含DataSource和JdbcTemplate属性）
• beans.xml中设置org.springframework.jdbc.datasource.DriverManagerDataSource及StudentJDBCTemplate为bean, 并将DriverManagerDataSource注入到StudentJDBCTemplate中。

注意：

• JdbcTemplate类执行SQL语句
• 数据源的配置及使用（注入的方式）
• 导入类时不要导错包
  • org.springframework.jdbc.core.JdbcTemplate
  • javax.sql.DataSource
  • org.springframework.jdbc.core.RowMapper

DriverManagerDataSource bean的设置是固定的，其属性及值参考下面的例子。

// StudentDao.java
public interface StudentDao {
    public void setDataSource(DataSource ds);
    public void create(String name, Integer age);
    public Student getStudent(Integer id);
    public List<Student> listStudents();
    public void delete(Integer id);
    public void update(Integer id, Integer age);
}

// StudentJDBCTemplate.java
public class StudentJDBCTemplate implements StudentDao{
    private DataSource dataSource;
    private JdbcTemplate JdbcTemplateObject;

    @Override
    public void setDataSource(DataSource ds) {
        this.dataSource = ds;
        this.JdbcTemplateObject = new JdbcTemplate(dataSource);
    }

    @Override
    public void create(String name, Integer age) {
        String sql = "insert into Student(name, age) values(?,?)";
        JdbcTemplateObject.update(sql, name, age);
        System.out.println("Created Record Name = "+name+" Age = "+age);
    }

    @Override
    public Student getStudent(Integer id) {
        String sql = "select * from Student where id = ?";
        Student student = JdbcTemplateObject.queryForObject(sql, new Object[]{id}, new StudentMapper());
        return student;
    }

    @Override
    public List<Student> listStudents() {
        String sql = "select * from student";
        List<Student> students = JdbcTemplateObject.query(sql, new StudentMapper());
        return students;
    }

    @Override
    public void delete(Integer id) {
        String sql = "delete from student where id = ?";
        JdbcTemplateObject.update(sql, id);
        System.out.println("Delete Record with ID = "+ id);
    }

    @Override
    public void update(Integer id, Integer age) {
        String sql = "update student set age=? where id = ?";
        JdbcTemplateObject.update(sql, age, id);
        System.out.println("Update Record with ID = "+id);
    }
}

// Student.java
public class Student {
    private Integer age;
    private String name;
    private Integer id;
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
}

// StudentMapper.java
public class StudentMapper implements RowMapper<Student>{

    @Override
    public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
        Student student = new Student();
        student.setId(rs.getInt("id"));
        student.setName(rs.getString("name"));
        student.setAge(rs.getInt("age"));
        return student;
    }
}

// MainApp.java
public class MainApp {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        StudentJDBCTemplate studentJDBCTemplate = (StudentJDBCTemplate) context.getBean("studentJDBCTemplate");
        System.out.println("----------插入记录---------");
        studentJDBCTemplate.create("Zara", 11);
        studentJDBCTemplate.create("Nuha", 2);
        studentJDBCTemplate.create("Ayan", 15);
        System.out.println("----------查询所有student记录----------");
        List<Student> students = studentJDBCTemplate.listStudents();
        for (Student student : students) {
            System.out.print("ID:"+student.getId());
            System.out.print(", Name:"+student.getName());
            System.out.println(", Age:"+student.getAge());
        }
        System.out.println("----------更新编号为2的学生的年龄为20----------");
        studentJDBCTemplate.update(2, 20);
        System.out.println("----------查询编号为2的学生的年龄----------");
        Student student = studentJDBCTemplate.getStudent(2);
        System.out.print("ID:"+student.getId());
        System.out.print(", Name:"+student.getName());
        System.out.println(", Age:"+student.getAge());
    }
}

// beans.xml
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/test"/>
        <property name="username" value="root"/>
        <property name="password" value="usbw"/>
    </bean>
    
    <bean id="studentJDBCTemplate" class="com.springjdbc.StudentJDBCTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>

运行结果：
----------插入记录---------
Created Record Name = Zara Age = 11
Created Record Name = Nuha Age = 2
Created Record Name = Ayan Age = 15
----------查询所有student记录----------
ID:1, Name:Zara, Age:11
ID:2, Name:Nuha, Age:2
ID:3, Name:Ayan, Age:15
----------更新编号为2的学生的年龄为20----------
Update Record with ID = 2
----------查询编号为2的学生的年龄----------
ID:2, Name:Nuha, Age:20