前端學PHP之物件導向系列第五篇物件操作

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目錄

[1]物件克隆 [2]物件比較[3]物件串列化[4]json

前面的話

　　本文主要介紹物件導向中的一些物件操作

 

對象克隆

　　物件複製，又叫物件克隆，可以透過 clone 關鍵字完成

　　在多數情況下，我們並不需要完全複製一個物件來獲得其中屬性。但有一個情況下確實需要：如果你有一個視窗對象，該對象持有視窗相關的資源。你可能會想複製一個新的窗口，保持所有屬性與原來的窗口相同，但必須是一個新的對象（因為如果不是新的對象，那麼一個窗口中的改變就會影響到另一個窗口）。還有一種情況：如果物件A 中保存著物件B 的引用，當你複製物件A時，你想其中使用的物件不再是物件B 而是B 的一個副本，那麼你必須得到物件A 的副本

<?<span style="color: #000000;">php
    </span><span style="color: #0000ff;">class</span><span style="color: #000000;"> Person{
        </span><span style="color: #0000ff;">private</span> <span style="color: #800080;">$name</span><span style="color: #000000;">;
        </span><span style="color: #0000ff;">private</span> <span style="color: #800080;">$sex</span><span style="color: #000000;">;
        </span><span style="color: #0000ff;">private</span> <span style="color: #800080;">$age</span><span style="color: #000000;">;
        </span><span style="color: #0000ff;">function</span> __construct(<span style="color: #800080;">$name</span>="",<span style="color: #800080;">$sex</span>="",<span style="color: #800080;">$age</span>=1<span style="color: #000000;">){
            </span><span style="color: #800080;">$this</span>->name= <span style="color: #800080;">$name</span><span style="color: #000000;">;
            </span><span style="color: #800080;">$this</span>->sex = <span style="color: #800080;">$sex</span><span style="color: #000000;">;
            </span><span style="color: #800080;">$this</span>->age = <span style="color: #800080;">$age</span><span style="color: #000000;">;
        }
        </span><span style="color: #0000ff;">function</span><span style="color: #000000;"> say(){
            </span><span style="color: #0000ff;">echo</span> "我的名字：" .<span style="color: #800080;">$this</span>->name."，性别：".<span style="color: #800080;">$this</span>->sex."，年龄：".<span style="color: #800080;">$this</span>->age."<br>"<span style="color: #000000;">;
        }
    }
    </span><span style="color: #800080;">$p1</span> = <span style="color: #0000ff;">new</span> Person('张三','男','20'<span style="color: #000000;">);
    </span><span style="color: #800080;">$p2</span> = <span style="color: #0000ff;">clone</span> <span style="color: #800080;">$p1</span><span style="color: #000000;">;
    </span><span style="color: #800080;">$p1</span>->say();<span style="color: #008000;">//</span><span style="color: #008000;">我的名字：张三，性别：男，年龄：20</span>
    <span style="color: #800080;">$p2</span>->say();<span style="color: #008000;">//</span><span style="color: #008000;">我的名字：张三，性别：男，年龄：20</span>
?>

 

物件比較

　　當使用比較運算子（==）比較兩個物件變數時，比較的原則是：如果兩個物件的屬性和屬性值都相等，而且兩個物件是同一個類別的實例，那麼這兩個對象變數相等

　　而如果使用全等運算子（===），這兩個物件變數一定要指向某個類別的同一個實例（即同一個物件）

<?<span style="color: #000000;">php
</span><span style="color: #0000ff;">function</span> bool2str(<span style="color: #800080;">$bool</span><span style="color: #000000;">)
{
    </span><span style="color: #0000ff;">if</span> (<span style="color: #800080;">$bool</span> === <span style="color: #0000ff;">false</span><span style="color: #000000;">) {
        </span><span style="color: #0000ff;">return</span> 'FALSE'<span style="color: #000000;">;
    } </span><span style="color: #0000ff;">else</span><span style="color: #000000;"> {
        </span><span style="color: #0000ff;">return</span> 'TRUE'<span style="color: #000000;">;
    }
}
</span><span style="color: #0000ff;">function</span> compareObjects(&<span style="color: #800080;">$o1</span>, &<span style="color: #800080;">$o2</span><span style="color: #000000;">)
{
    </span><span style="color: #0000ff;">echo</span> 'o1 == o2 : ' . bool2str(<span style="color: #800080;">$o1</span> == <span style="color: #800080;">$o2</span>) . "\n"<span style="color: #000000;">;
    </span><span style="color: #0000ff;">echo</span> 'o1 != o2 : ' . bool2str(<span style="color: #800080;">$o1</span> != <span style="color: #800080;">$o2</span>) . "\n"<span style="color: #000000;">;
    </span><span style="color: #0000ff;">echo</span> 'o1 === o2 : ' . bool2str(<span style="color: #800080;">$o1</span> === <span style="color: #800080;">$o2</span>) . "\n"<span style="color: #000000;">;
    </span><span style="color: #0000ff;">echo</span> 'o1 !== o2 : ' . bool2str(<span style="color: #800080;">$o1</span> !== <span style="color: #800080;">$o2</span>) . "\n"<span style="color: #000000;">;
}
</span><span style="color: #0000ff;">class</span><span style="color: #000000;"> Flag
{
    </span><span style="color: #0000ff;">public</span> <span style="color: #800080;">$flag</span><span style="color: #000000;">;
    </span><span style="color: #0000ff;">function</span> Flag(<span style="color: #800080;">$flag</span> = <span style="color: #0000ff;">true</span><span style="color: #000000;">) {
        </span><span style="color: #800080;">$this</span>->flag = <span style="color: #800080;">$flag</span><span style="color: #000000;">;
    }
}
</span><span style="color: #0000ff;">class</span><span style="color: #000000;"> OtherFlag
{
    </span><span style="color: #0000ff;">public</span> <span style="color: #800080;">$flag</span><span style="color: #000000;">;
    </span><span style="color: #0000ff;">function</span> OtherFlag(<span style="color: #800080;">$flag</span> = <span style="color: #0000ff;">true</span><span style="color: #000000;">) {
        </span><span style="color: #800080;">$this</span>->flag = <span style="color: #800080;">$flag</span><span style="color: #000000;">;
    }
}

</span><span style="color: #800080;">$o</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> Flag();
</span><span style="color: #800080;">$p</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> Flag();
</span><span style="color: #800080;">$q</span> = <span style="color: #800080;">$o</span><span style="color: #000000;">;
</span><span style="color: #800080;">$r</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> OtherFlag();
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
Two instances of the same class
o1 == o2 : TRUE
o1 != o2 : FALSE
o1 === o2 : FALSE
o1 !== o2 : TRUE
 </span><span style="color: #008000;">*/</span>
<span style="color: #0000ff;">echo</span> "Two instances of the same class\n"<span style="color: #000000;">;
compareObjects(</span><span style="color: #800080;">$o</span>, <span style="color: #800080;">$p</span><span style="color: #000000;">);
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
Two references to the same instance
o1 == o2 : TRUE
o1 != o2 : FALSE
o1 === o2 : TRUE
o1 !== o2 : FALSE
 </span><span style="color: #008000;">*/</span>
<span style="color: #0000ff;">echo</span> "\nTwo references to the same instance\n"<span style="color: #000000;">;
compareObjects(</span><span style="color: #800080;">$o</span>, <span style="color: #800080;">$q</span><span style="color: #000000;">);
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
Instances of two different classes
o1 == o2 : FALSE
o1 != o2 : TRUE
o1 === o2 : FALSE
o1 !== o2 : TRUE
 </span><span style="color: #008000;">*/</span>
<span style="color: #0000ff;">echo</span> "\nInstances of two different classes\n"<span style="color: #000000;">;
compareObjects(</span><span style="color: #800080;">$o</span>, <span style="color: #800080;">$r</span><span style="color: #000000;">);
</span>?>

 

物件串列化

　　物件是一種在記憶體中儲存的資料類型，它的壽命通常隨著產生該物件的程式終止而終止。有時候可能需要將物件的狀態保存下來，需要時再將物件恢復。物件透過寫出描述自己狀態的數值來記錄自己，這個過程稱為物件的串列化（Serialization）。以下兩種情況需要將物件串列化：1、物件需要在網路中傳輸時，將物件串列化成二進位串即可；2、物件需要持久保存時，將物件串列化後寫入檔案或資料庫

serialize()

　　serialize() -- 串列化，傳回一個包含位元組流的字串

unserialize()

　　unserialize() -- 反串列化，能夠重新把字串變回php原來的物件值

　　串化一個物件將會保存物件的所有屬性變數和類別名稱訊息，但是不會保存物件的方法

<?<span style="color: #000000;">php
</span><span style="color: #008000;">//</span><span style="color: #008000;"> classa.inc:</span>
  <span style="color: #0000ff;">class</span><span style="color: #000000;"> A {
      </span><span style="color: #0000ff;">public</span> <span style="color: #800080;">$one</span> = 1<span style="color: #000000;">;
      </span><span style="color: #0000ff;">public</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> show_one() {
          </span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$this</span>-><span style="color: #000000;">one;
      }
  }
  
</span><span style="color: #008000;">//</span><span style="color: #008000;"> page1.php:</span>
  <span style="color: #0000ff;">include</span>("classa.inc"<span style="color: #000000;">);
  </span><span style="color: #800080;">$a</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> A;
  </span><span style="color: #800080;">$s</span> = <span style="color: #008080;">serialize</span>(<span style="color: #800080;">$a</span><span style="color: #000000;">);
  </span><span style="color: #008000;">//</span><span style="color: #008000;"> 把变量$s保存起来以便文件page2.php能够读到</span>
  <span style="color: #008080;">file_put_contents</span>('store', <span style="color: #800080;">$s</span><span style="color: #000000;">);

</span><span style="color: #008000;">//</span><span style="color: #008000;"> page2.php:</span>
  <span style="color: #0000ff;">include</span>("classa.inc"<span style="color: #000000;">);
  </span><span style="color: #800080;">$s</span> = <span style="color: #008080;">file_get_contents</span>('store'<span style="color: #000000;">);
  </span><span style="color: #800080;">$a</span> = <span style="color: #008080;">unserialize</span>(<span style="color: #800080;">$s</span><span style="color: #000000;">);
  </span><span style="color: #008000;">//</span><span style="color: #008000;"> 现在可以使用对象$a里面的函数 show_one()</span>
  <span style="color: #800080;">$a</span>-><span style="color: #000000;">show_one();
</span>?>

 

json

json_encode

<span style="color: #0000ff;">string</span> json_encode ( <span style="color: #0000ff;">mixed</span> <span style="color: #800080;">$value</span> [, int <span style="color: #800080;">$options</span> = 0 [, int <span style="color: #800080;">$depth</span> = 512 ]] )

　　json_encode()方法對變數進行 JSON 編碼

<?<span style="color: #000000;">php
</span><span style="color: #800080;">$arr</span> = <span style="color: #0000ff;">array</span> ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5<span style="color: #000000;">);
</span><span style="color: #0000ff;">echo</span> json_encode(<span style="color: #800080;">$arr</span>);<span style="color: #008000;">//</span><span style="color: #008000;">{"a":1,"b":2,"c":3,"d":4,"e":5}</span>
?>

json_decode

<span style="color: #0000ff;">mixed</span> json_decode ( <span style="color: #0000ff;">string</span> <span style="color: #800080;">$json</span> [, bool <span style="color: #800080;">$assoc</span> = <span style="color: #0000ff;">false</span> [, int <span style="color: #800080;">$depth</span> = 512 [, int <span style="color: #800080;">$options</span> = 0 ]]] )

　　json_decode()方法對 JSON 格式的字串進行解碼，接受一個 JSON 編碼的字串並且把它轉換為 PHP 變量，當assoc參數為 TRUE 時，將傳回 array 而非 object

<?<span style="color: #000000;">php
</span><span style="color: #800080;">$json</span> = '{"a":1,"b":2,"c":3,"d":4,"e":5}'<span style="color: #000000;">;
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
object(stdClass)#1 (5) {
    ["a"] => int(1)
    ["b"] => int(2)
    ["c"] => int(3)
    ["d"] => int(4)
    ["e"] => int(5)
}
 <span style="color: #008000;">*/</span>
<span style="color: #008080;">var_dump</span>(json_decode(<span style="color: #800080;">$json</span><span style="color: #000000;">));

</span><span style="color: #008000;">/*</span><span style="color: #008000;">
array(5) {
    ["a"] => int(1)
    ["b"] => int(2)
    ["c"] => int(3)
    ["d"] => int(4)
    ["e"] => int(5)
}
 </span><span style="color: #008000;">*/</span>
<span style="color: #008080;">var_dump</span>(json_decode(<span style="color: #800080;">$json</span>, <span style="color: #0000ff;">true</span><span style="color: #000000;">));
</span>?>