PHP的Try, throw 和 catch简单用法
PHP的Try, throw 和 catch简单用法
本文简单记录一下关于php中的 Try, throw 和 catch 的用法,后面有时间再做一个详细的解析。
Try - 使用异常的函数应该位于 "try" 代码块内。如果没有触发异常,则代码将照常继续执行。但是如果异常被触发,会抛出一个
异常。
Throw - 这里规定如何触发异常。每一个 "throw" 必须对应至少一个 "catch"
Catch - "catch" 代码块会捕获异常,并创建一个包含异常信息的对象
让我们触发一个异常:
<?php //创建可抛出一个异常的函数 function checkNum($number){ if($number>1){ throw new Exception("Value must be 1 or below"); } return true; } //在 "try" 代码块中触发异常 try{ checkNum(2); //捕获异常 }catch(Exception $e){ echo 'Message: ' .$e->getMessage(); }
上面代码将获得类似这样一个错误:
Message: Value must be 1 or below
例子解释:
上面的代码抛出了一个异常,并捕获了它:
创建 checkNum() 函数。它检测数字是否大于 1。如果是,则抛出一个异常。
在 "try" 代码块中调用 checkNum() 函数。
checkNum() 函数中的异常被抛出
"catch" 代码块接收到该异常,并创建一个包含异常信息的对象 ($e)。
通过从这个 exception 对象调用 $e->getMessage(),输出来自该异常的错误消息,不过,为了遵循“每个 throw 必须对应一个
catch 的原则,可以设置一个顶层的异常处理器来处理漏掉的错误。
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