025-11月29日-PHP第15节-抽象类、接口

1. 抽象类

抽象类可以有抽象方法，也可以有普通方法

abstract class operate{
        public $a;
        public $b;
//$a与$b注释掉也没问题
//        public $sum;
//        public $difference;
        public function __construct($a,$b){
            $this->a = $a;
            $this ->b = $b;
        }//如果需要给类的实例最初赋值，必须要用构造方法
        abstract public function sum();
        abstract public function difference();
    }
    class operate_detail extends operate{
        public function sum(){
            return  $this->a+$this->b;
        }
        public function difference(){
            return $this->a-$this->b;
        }
    }
//    $o = new operate(100,50);
// Cannot instantiate 无法实例化
    $o_d =new operate_detail(100,50);
    var_dump($o_d->sum());
    echo '<hr>';
    echo $o_d->difference();

2. 接口

接口是制定规则，只有抽象函数和常量

interface operate2{
        const PRODUCT = '积为：';
        const QUOTIENT = '商为：';
        public function result($c,$d);
        //注意这个地方没有abstract因为interface默认了方法就是抽象的
    }
    class operate2_detail implements operate2{
        public function result($c, $d)
        {
            $result1 = $c*$d;
            $result2 = $c/$d;
            return $c.'与'.$d.'  '.self::PRODUCT.$result1.' --- '.self::QUOTIENT.$result2;
            //常量调用要用self::
//            return self::PRODUCT.$result1 . '---' . self::QUOTIENT.$result2; '---'前后用不用空格都一样,''里能体现空格
            // TODO: Implement result() method.
        }
    }
    $o_d2 = new operate2_detail();
    echo $o_d2->result(100,50);

1，2题运行结果

3. 上次的作业写好

按照接口的方式来写，将其简化为4个操作方法：create(insert)、read(select)、update、delete。

interface curd{
        public function creat($data);
        public function update($data,$where);
        public function read($fields, $where, $order, $limit);
        public function delete($where);
    }
    class DB2 implements curd
    {
        public $pdo;
        public $table;
        public function __construct($dsn, $user, $password, $table)
        {
            $this->table = $table;
            $this->pdo = new PDO($dsn, $user, $password);
            //已经预处理，后面函数不用添加此语句了
        }
        public function read($fields, $where = '', $order = '', $limit = '')
        {
            //            $this->table = $table;
            $sql = 'SELECT ';
            if (is_array($fields)) {
                foreach ($fields as $field) {
                    $sql .= $field . ', ';
                }
            } else {
                $sql .= $fields;
            }
            $sql = rtrim(trim($sql), ',');
            $sql .= '  FROM ' . $this->table;
            //查询条件
            if (!empty($where)) {
                $sql .= ' WHERE ' . $where;
            }
            //排序条件
            if (!empty($order)) {
                $sql .= ' order by ' . $order;
            }
            //分页条件
            if (!empty($limit)) {
                $sql .= ' limit ' . $limit;
            }
            $sql .= ';';
            //创建PDO预处理对象
            $stmt = $this->pdo->prepare($sql);
            //执行查询操作
            if ($stmt->execute()) {
                if ($stmt->rowCount() > 0) {
                    $stmt->setFetchMode(PDO::FETCH_ASSOC);
                    //返回一个二维数组
                    return $stmt->fetchAll();
                }
            } else {
                return false;
            }
        }
        public function creat($data = [])
        {
            $sql = "INSERT INTO {$this->table} SET ";
            //组装插入语句
            if (is_array($data)) {
                foreach ($data as $k => $v) {
                    $sql .= $k . '="' . $v . '", ';
                }
            } else {
                return false;
            }
            //去掉尾部逗号,并添加分号结束
            $sql = rtrim(trim($sql), ',') . ';';
            //创建PDO预处理对象
            $stmt = $this->pdo->prepare($sql);
            //执行新增操作
            if ($stmt->execute()) {
                if ($stmt->rowCount() > 0) {
                    return true;
                }
            } else {
                return false;
            }
        }
        public function update($data = [], $where = '')
        {
            $sql = "UPDATE {$this->table} SET ";
            //组装修改语句
            if (is_array($data)) {
                foreach ($data as $k => $v) {
                    $sql .= $k . '="' . $v . '", ';
                }
            }
            //去掉尾部逗号,并添加分号结束
            $sql = rtrim(trim($sql), ',');
            //查询条件
            if (!empty($where)) {
                $sql .= ' WHERE ' . $where;
            }
            //创建PDO预处理对象
            $stmt = $this->pdo->prepare($sql);
            //执行新增操作
            if ($stmt->execute()) {
                if ($stmt->rowCount() > 0) {
                    return true;
                }
            } else {
                return false;
            }
        }
        public function delete($where = '')
        {
            $sql = "DELETE FROM {$table}  ";
            //查询条件
            if (!empty($where)) {
                $sql .= ' WHERE ' . $where;
            }
            //创建PDO预处理对象
            $stmt = $this->pdo->prepare($sql);
            //执行删除操作
            if ($stmt->execute()) {
                if ($stmt->rowCount() > 0) {
                    return true;
                }
            } else {
                return false;
            }
        }
    }
    $db2 = new DB2('mysql:host=localhost;dbname=anguoguo','root','root','movies');
    //连接pdo
    print_r($db2);
    print_r($db2->read('name','cate_id=2','mov_id DESC')) ;
    echo '<hr/>';
    $array3 =[
    'mov_id' =>10,
    'name' =>'插入',
    'image'=>'10.jpg',
    'detail'=>'能否插入成功',
    'cate_id'=>'4'
    ];
    print_r($db2->creat('$array3'));
    echo '<hr/>';
    $array4 =['image'=>'101.jpg'];
    print_r($db2->update($array4,'mov_id=5'));
    echo '<hr/>';
    print_r( $db2->delete(''));
    echo '<hr/>';
    $array5 =['image'=>'5.jpg'];
    print_r($db2->update($array5,'mov_id=5'));
    echo '<hr/>';

结果为：