这篇文章来分享下api接口对接如何实现，还有源码，希望对新手有所帮助。

什么是API?

我的回答：API（ 应用程序编程接口）：一般来说，这是一套明确定义的各种软件组件之间的通信方法。

什么是API？我们不妨用一个小故事展示出来：

研发人员A开发了软件A，研发人员B正在研发软件B。

有一天，研发人员B想要调用软件A的部分功能来用，但是他又不想从头看一遍软件A的源码和功能实现过程，怎么办呢？

研发人员A想了一个好主意：我把软件A里你需要的功能打包好，写成一个函数；你按照我说的流程，把这个函数放在软件B里，就能直接用我的功能了！

其中，API就是研发人员A说的那个函数。

进一步解释:

比如c语言的fopen（）函数来打开一个文件，感觉非常简单。

但是操作到底层是非常复杂的，打开文件需要扫描硬盘，找到我文件位置，然后读取部分数据，并放进i/o缓存中，放进内存。

这些数据都是0，1序列，还要对照ASCII表或者unicode表翻译成字符，再在显示器上显示出来。如果这个过程让程序员来完成，简直就是个噩梦。不可能的事。

怎么办呢？

操作系统就想了一个很好的办法。它预先把复杂的操作写在一个函数里面，编译成一个组件（一般是动态链接库）程序员只需要简单的调用这些函数就可以用完成复杂的工作。

这些封装好的函数就叫做API。

getMessage();$LabelArray[$content_tag_name] .= $e->getMessage();}break;default:
}echo serialize($LabelArray);function compose_article($title, $content) {$separator = compose_separator();return $title.$separator.$content;
}function compose_separator() {return PHP_EOL.'('.TITLE_SEPAR2.')'.PHP_EOL;
}function fix_separator($article) {return $article;
}function get_wyc_article($str) {global $url;$separator = compose_separator();$separator = str_replace(PHP_EOL, '', $separator);$wyc = curl_request($url, array('wenzhang'=>$str));$wyc_f = $wyc;$wyc = fix_separator($wyc);$wyc = explode($separator, $wyc);if (isset($wyc[0])){$wyc[0] = str_replace('标题：', '', $wyc[0]);$wyc[0] = str_replace('标题:', '', $wyc[0]);$wyc[0] = str_replace('目：', '', $wyc[0]);$wyc[0] = str_replace('目:', '', $wyc[0]);$wyc[0] = 'xx`xx'.$wyc[0];$wyc[0] = str_replace('xx`xx题', '', $wyc[0]);$wyc[0] = str_replace('xx`xx', '', $wyc[0]);}return $wyc;
}function get_wyc_title($str) {$title = get_wyc_article($str.PHP_EOL.PHP_EOL.PHP_EOL.$str.PHP_EOL.PHP_EOL.PHP_EOL.$str);$title = fix_newline($title);$title = explode(PHP_EOL, $title);return $title[0];
}function get_keywords($title, $contents) {$url_kw = 'http://api-2.78tp.com/nlp/kws.php?appid=';$kws = curl_request($url_kw, array('title'=>$title,'len'=>100,'text'=>$contents));return $kws;
}function remove_alt($contents) {$contents = preg_replace('/alt=\"(.*)\"/', '', $contents);return $contents;
}function fix_title($contents) {$punctuation_symbol = array('。', '？', '，', '：', '；', '、', '！','.',  '?',  ',',  ':',  ';', '!');$contents = str_replace($punctuation_symbol, '', $contents);return $contents;
}function br2newline($contents) {$contents = str_replace('
', PHP_EOL, $contents);$contents = str_replace('
', PHP_EOL, $contents);$contents = str_replace('
', PHP_EOL, $contents);$contents = str_replace('
', PHP_EOL, $contents);$contents = str_replace('
', PHP_EOL, $contents);$contents = str_replace('
', PHP_EOL, $contents);return $contents;
}function newline2br($contnets) {$contnets = str_replace(PHP_EOL, "
", $contnets);$contnets = str_replace('

', '
', $contnets);return $contnets;
}function delete_newline($contents) {$contents = fix_newline($contents);return $contents;
}function reset_newline_win($contents) {// 优化换行符$contents = str_replace("\r\n", "\n", $contents);$contents = str_replace("\r", "\n", $contents);$contents = str_replace("\n", PHP_EOL, $contents);return $contents;
}function fix_newline($data) {$data = str_replace("\r", "\n", $data);while(strpos($data, "\n\n") !== false) {$data = str_replace("\n\n", "\n", $data);}$data = str_replace("\n", PHP_EOL, $data);return $data;
}function clean_contents($contents) {$sa = new cleanHtml;  $sa->allow = array( 'src' );    $sa->exceptions = array(  'img' => array( 'src', 'alt' ),  //'a' => array( 'href', 'title' ),  'iframe'=>array('src','frameborder'),  ); $str = $sa->strip( $contents );   return $str;
}function xfm_strong_str_replace_once($search, $replace, $subject) {$firstChar = strpos($subject, $search);if($firstChar !== false) {$beforeStr = substr($subject,0,$firstChar);$afterStr = substr($subject, $firstChar + strlen($search));return $beforeStr.$replace.$afterStr;} else {return $subject;}
}//参数1：访问的URL，参数2：post数据(不填则为GET)，参数3：提交的$cookies,参数4：是否返回$cookies
function curl_request($url,$post='',$cookie='', $returnCookie=0){if (! extension_loaded('curl')) {file_exists('./ext/php_curl.dll') && dl('php_curl.dll'); // 加载扩展}$curl = curl_init();curl_setopt($curl, CURLOPT_URL, $url);curl_setopt($curl, CURLOPT_USERAGENT, 'Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; Trident/6.0)');if (ini_get('open_basedir') == '' && strtolower(ini_get('safe_mode')) != 'on'){ curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);}curl_setopt($curl, CURLOPT_AUTOREFERER, 1);curl_setopt($curl, CURLOPT_REFERER, "http://XXX");if($post) {curl_setopt($curl, CURLOPT_POST, 1);curl_setopt($curl, CURLOPT_POSTFIELDS, http_build_query($post));}if($cookie) {curl_setopt($curl, CURLOPT_COOKIE, $cookie);}curl_setopt($curl, CURLOPT_HEADER, $returnCookie);curl_setopt($curl, CURLOPT_TIMEOUT, 150);curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);$data = curl_exec($curl);if (curl_errno($curl)) {return curl_error($curl);}curl_close($curl);if($returnCookie){list($header, $body) = explode("\r\n\r\n", $data, 2);preg_match_all("/Set\-Cookie:([^;]*);/", $header, $matches);$info['cookie']  = substr($matches[1][0], 1);$info['content'] = $body;return $info;}else{return $data;}
}//echo $tag;
// 计算中文字符串长度
function utf8_strlen($string = null) {
// 将字符串分解为单元
preg_match_all("/./us", $string, $match);
// 返回单元个数
return count($match[0]);
}function reg_escape( $str )  
{  $conversions = array( "^" => "\^", "[" => "\[", "." => "\.", "$" => "\$", "{" => "\{", "*" => "\*", "(" => "\(", "\\" => "\\\\", "/" => "\/", "+" => "\+", ")" => "\)", "|" => "\|", "?" => "\?", "<" => "\<", ">" => "\>" );  return strtr( $str, $conversions );  
}  /** 
* Strip attribute Class 
* Remove attributes from XML elements 
* @author David (semlabs.co.uk) 
* @version 0.2.1 
*/  class cleanHtml{  public $str         = '';  public $allow       = array();  public $exceptions  = array();  public $ignore      = array();  public function strip( $str )  {  $this->str = $str;  if( is_string( $str ) && strlen( $str ) > 0 )  {  $res = $this->findElements();  if( is_string( $res ) )  return $res;  $nodes = $this->findAttributes( $res );  $this->removeAttributes( $nodes );  }  return $this->str;  }  private function findElements()  {  # Create an array of elements with attributes  $nodes = array();  preg_match_all( "/<([^ !\/\>\n]+)([^>]*)>/i", $this->str, $elements );  foreach( $elements[1] as $el_key => $element )  {  if( $elements[2][$el_key] )  {  $literal = $elements[0][$el_key];  $element_name = $elements[1][$el_key];  $attributes = $elements[2][$el_key];  if( is_array( $this->ignore ) && !in_array( $element_name, $this->ignore ) )  $nodes[] = array( 'literal' => $literal, 'name' => $element_name, 'attributes' => $attributes );  }  }  # Return the XML if there were no attributes to remove  if( !$nodes[0] )  return $this->str;  else  return $nodes;  }  private function findAttributes( $nodes )  {  # Extract attributes  foreach( $nodes as &$node )  {  preg_match_all( "/([^ =]+)\s*=\s*[\"|']{0,1}([^\"']*)[\"|']{0,1}/i", $node['attributes'], $attributes );  if( $attributes[1] )  {  foreach( $attributes[1] as $att_key => $att )  {  $literal = $attributes[0][$att_key];  $attribute_name = $attributes[1][$att_key];  $value = $attributes[2][$att_key];  $atts[] = array( 'literal' => $literal, 'name' => $attribute_name, 'value' => $value );  }  }  else  $node['attributes'] = null;  $node['attributes'] = $atts;  unset( $atts );  }  return $nodes;  }  private function removeAttributes( $nodes )  {  # Remove unwanted attributes  foreach( $nodes as $node )  {  # Check if node has any attributes to be kept  $node_name = $node['name'];  $new_attributes = '';  if( is_array( $node['attributes'] ) )  {  foreach( $node['attributes'] as $attribute )  {  if( ( is_array( $this->allow ) && in_array( $attribute['name'], $this->allow ) ) || $this->isException( $node_name, $attribute['name'], $this->exceptions ) )  $new_attributes = $this->createAttributes( $new_attributes, $attribute['name'], $attribute['value'] );  }  }  $replacement = ( $new_attributes ) ? "<$node_name $new_attributes>" : "<$node_name>";  $this->str = preg_replace( '/'. reg_escape( $node['literal'] ) .'/', $replacement, $this->str );  }  }  private function isException( $element_name, $attribute_name, $exceptions )  {  if( array_key_exists($element_name, $this->exceptions) )  {  if( in_array( $attribute_name, $this->exceptions[$element_name] ) )  return true;  }  return false;  }  private function createAttributes( $new_attributes, $name, $value )  {  if( $new_attributes )  $new_attributes .= " ";  $new_attributes .= "$name=\"$value\"";  return $new_attributes;  }  }  ?>

参考：如何对接伪原创API 更加通俗讲:别人写好的代码，或者编译好的程序，提供给你使用，就叫做api。

因为你使用了别人的代码（ 或者程序）中的某个函数，类，对象，就叫做使用了某个api。