对于一个网站来说，肯定会需要一个提供验证功能的页面。那么我们现在就需要考虑验证页面中的验证码的应用了。我们接下来将要为大家具体讲解有关一、准备一个展示并提交PHP验证码的页面
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<li class="alt"><span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> </span></span></li>
<li class=""><span> </span></li>
<li class="alt">
<span> @header("content-type:text/html; </span><span class="attribute"><font color="#ff0000">charset</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">UTF</font></span><span>-8"); </span>
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<li class=""><span> </span></li>
<li class="alt"><span> //打开session </span></li>
<li class=""><span> </span></li>
<li class="alt"><span> session_start(); </span></li>
<li class=""><span> </span></li>
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<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span>
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<li class=""><span> </span></li>
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<span></span><strong><font color="#006699"><span class="tag"><span class="tag-name">html</span><span class="tag">></span></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">head</span><span class="tag">></span></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">meta</span></span></font></strong><span> </span><span class="attribute"><font color="#ff0000">http-equiv</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"Content-Type"</font></span><span> </span><span class="attribute"><font color="#ff0000">content</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"text/html; charset=utf-8"</font></span><span> </span><span class="tag"><strong><font color="#006699">/></font></strong></span><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">title</span><span class="tag">></span></span></font></strong><span>PHP验证码示例</span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">title</span><span class="tag">></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">head</span><span class="tag">></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">body</span><span class="tag">></span></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> 验证码：</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span><span class="tag">/></span></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">iframe</span></span></font></strong><span> </span><span class="attribute"><font color="#ff0000">id</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"iimg"</font></span><span> </span><span class="attribute"><font color="#ff0000">height</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"100"</font></span><span> </span><span class="attribute"><font color="#ff0000">width</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">300</font></span><span> </span><span class="attribute"><font color="#ff0000">src</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"img.php"</font></span><span> </span><span class="attribute"><font color="#ff0000">frameborder</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"0"</font></span><span> </span><strong><font color="#006699"><span class="tag">></span><span class="tag"></span><span class="tag-name">iframe</span><span class="tag">></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span><span class="tag">/></span></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">input</span></span></font></strong><span> </span><span class="attribute"><font color="#ff0000">type</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">button</font></span><span> </span><span class="attribute"><font color="#ff0000">value</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"看不清，换一张"</font></span><span> </span><span class="attribute"><font color="#ff0000">onclick</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"iimg.location.reload();"</font></span><span class="tag"><strong><font color="#006699">></font></strong></span><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span><span class="tag">></span></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">form</span></span></font></strong><span> </span><span class="attribute"><font color="#ff0000">action</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"validate.php"</font></span><span> </span><span class="attribute"><font color="#ff0000">method</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"post"</font></span><span class="tag"><strong><font color="#006699">></font></strong></span><span> </span>
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<li class=""><span> </span></li>
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<span> 输入验证码：</span><strong><font color="#006699"><span class="tag"><span class="tag-name">input</span></span></font></strong><span> </span><span class="attribute"><font color="#ff0000">name</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"imgId"</font></span><span> </span><span class="attribute"><font color="#ff0000">style</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"width:60"</font></span><span class="tag"><strong><font color="#006699">></font></strong></span><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"><span class="tag-name">input</span></span></font></strong><span> </span><span class="attribute"><font color="#ff0000">type</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"submit"</font></span><span> </span><span class="attribute"><font color="#ff0000">value</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">"确定"</font></span><span class="tag"><strong><font color="#006699">></font></strong></span><span> </span>
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<span> </span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">form</span><span class="tag">></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span> </span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">body</span><span class="tag">></span></font></strong><span> </span>
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<li class=""><span> </span></li>
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<span></span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">html</span><span class="tag">></span></font></strong><span> </span>
</li>
</ol>二、以下是PHP验证码生成页面，该页面在第一页面中被调用
<ol class="dp-xml">
<li class="alt"><span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> </span></span></li>
<li class=""><span> </span></li>
<li class="alt"><span>Header("Content-type: image/gif"); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>session_start(); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>//验证码为随机字符，以下是算法 </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>$randval; </span></li>
<li class=""><span> </span></li>
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<span>for($</span><span class="attribute"><font color="#ff0000">i</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">0</font></span><span>;$i</span><strong><font color="#006699"><span class="tag"><span class="tag-name">7</span></span></font></strong><span>;$i++){ </span>
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<li class=""><span> </span></li>
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<span> $</span><span class="attribute"><font color="#ff0000">randstr</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">mt_rand</font></span><span>(ord('A'),ord('Z')); </span>
</li>
<li class=""><span> </span></li>
<li class="alt"><span> srand((double)microtime()*1000000); </span></li>
<li class=""><span> </span></li>
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<span> $</span><span class="attribute"><font color="#ff0000">randv</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">mt_rand</font></span><span>(0,10); </span>
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<li class=""><span> </span></li>
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<span> if($randv%</span><span class="attribute"><font color="#ff0000">2</font></span><span>==0){ </span>
</li>
<li class=""><span> </span></li>
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<span> $</span><span class="attribute"><font color="#ff0000">randval.</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">mt_rand</font></span><span>(0,10); </span>
</li>
<li class=""><span> </span></li>
<li class="alt"><span> }else{ </span></li>
<li class=""><span> </span></li>
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<span> $</span><span class="attribute"><font color="#ff0000">randval.</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">chr</font></span><span>($randstr); </span>
</li>
<li class=""><span> </span></li>
<li class="alt"><span> } </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>} </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>//注册PHP验证码到session </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>session_register($randval); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>//以下是绘制验证码图 </span></li>
<li class=""><span> </span></li>
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<span>$</span><span class="attribute"><font color="#ff0000">height</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">50</font></span><span>;//图高 </span>
</li>
<li class=""><span> </span></li>
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<span>$</span><span class="attribute"><font color="#ff0000">width</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">100</font></span><span>;//图宽 </span>
</li>
<li class=""><span> </span></li>
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<span>$</span><span class="attribute"><font color="#ff0000">im</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">ImageCreateTrueColor</font></span><span>($width, $height); </span>
</li>
<li class=""><span> </span></li>
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<span>$</span><span class="attribute"><font color="#ff0000">white</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">ImageColorAllocate</font></span><span>($im, 255, 255, 255); </span>
</li>
<li class=""><span> </span></li>
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<span>$</span><span class="attribute"><font color="#ff0000">blue</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">ImageColorAllocate</font></span><span>($im, 0, 0, 64); </span>
</li>
<li class=""><span> </span></li>
<li class="alt"><span>ImageFill($im, 0, 0, $white); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>srand((double)microtime()*1000000000); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>ImageLine($im, mt_rand(0,$width/3), mt_rand(0,$height/3), mt_rand($width/3,$width), mt_rand($height/3,$height), $blue); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>srand((double)microtime()*1000000); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>ImageLine($im, mt_rand($width/3,$width), mt_rand(0,$height/3), mt_rand(0,$width/3), mt_rand(0,$height/3), $blue); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>srand((double)microtime()*1000000); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>ImageString($im,16 , mt_rand(0,$width - strlen($randval) * 10), mt_rand(0,$height-12), $randval, $blue); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>ImageGIF($im); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>ImageDestroy($im); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>/* </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>需要注意的是：为了支持以上绘图函数，我们必须在PHP载入GD2图形处理库，可修改 php.ini 文件中的 </span></li>
<li class=""><span> </span></li>
<li class="alt">
<span>;</span><span class="attribute"><font color="#ff0000">extension</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">php_gd2</font></span><span>.dll </span>
</li>
<li class=""><span> </span></li>
<li class="alt"><span>为 </span></li>
<li class=""><span> </span></li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">extension</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">php_gd2</font></span><span>.dll </span>
</li>
<li class=""><span> </span></li>
<li class="alt"><span>即开启GD2库 </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>*/ </span></li>
<li class=""><span> </span></li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span>
</li>
</ol>三、这是验证页面，提示PHP验证码是否通过验证
<ol class="dp-xml">
<li class="alt"><span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> @header("content-type:text/html; </span><span class="attribute"><font color="#ff0000">charset</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">UTF</font></span><span>-8"); </span></span></li>
<li class=""><span> </span></li>
<li class="alt"><span> //开启session </span></li>
<li class=""><span> </span></li>
<li class="alt"><span> session_start(); </span></li>
<li class=""><span> </span></li>
<li class="alt"><span> //得到用户输入的验证码，并转换成大写 </span></li>
<li class=""><span> </span></li>
<li class="alt">
<span> $</span><span class="attribute"><font color="#ff0000">imgId_req</font></span><span> = $_REQUEST['imgId']; </span>
</li>
<li class=""><span> </span></li>
<li class="alt">
<span> $</span><span class="attribute"><font color="#ff0000">imgId_req</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">strtoupper</font></span><span>($imgId_req); </span>
</li>
<li class=""><span> </span></li>
<li class="alt"><span> //验证该字符串是否注册了session变量 </span></li>
<li class=""><span> </span></li>
<li class="alt"><span> if (session_is_registered($imgId_req)) { </span></li>
<li class=""><span> </span></li>
<li class="alt">
<span> echo "</span><strong><font color="#006699"><span class="tag"><span class="tag-name">font</span></span></font></strong><span> </span><span class="attribute"><font color="#ff0000">color</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">blue</font></span><span> </span><span class="tag"><strong><font color="#006699">></font></strong></span><span>通过验证！</span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">font</span><span class="tag">></span></font></strong><span>"; </span>
</li>
<li class=""><span> </span></li>
<li class="alt"><span> } else { </span></li>
<li class=""><span> </span></li>
<li class="alt">
<span> echo "</span><strong><font color="#006699"><span class="tag"><span class="tag-name">font</span></span></font></strong><span> </span><span class="attribute"><font color="#ff0000">color</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">red</font></span><span> </span><span class="tag"><strong><font color="#006699">></font></strong></span><span>验证错误！</span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">font</span><span class="tag">></span></font></strong><span>"; </span>
</li>
<li class=""><span> </span></li>
<li class="alt"><span> } </span></li>
<li class=""><span> </span></li>
<li class="alt"><span> //关闭session，以清除所有注册过的变量 </span></li>
<li class=""><span> </span></li>
<li class="alt"><span> session_destroy(); </span></li>
<li class=""><span> </span></li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span>
</li>
</ol>
