php中SimpleXML生成与解析xml文件

class SimpleXMLExtended extends SimpleXMLElement {
  public function addCData($cdata_text) {
    $node = dom_import_simplexml($this);
    $no   = $node->ownerDocument;
    $node->appendChild($no->createCDATASection($cdata_text));
    }
  }
function array2xml($array, $xml = false){
    if($xml === false){
        $xml = new SimpleXMLExtended('<root/>');
    }
    foreach($array as $key => $value){
        if(is_array($value)){
            array2xml($value, $xml->addChild($key));
        }else{
            //如果包含汉字，转编码
            if (preg_match("/([x81-xfe][x40-xfe])/", $value, $match)) {
                $value = iconv('gbk', 'utf-8', $value);
            }
            $xml->$key = NULL; // VERY IMPORTANT! We need a node where to append
            $xml->$key->addCData($value);
            //$xml->$key->addAttribute('lang', 'en');
           // $xml->addChild($key, $value);
        }
    }
    return $xml->asXML();
}

<?php
$content = <<<XML
<?xml version="1.0" encoding="UTF-8"?>
<test>
 <global_setting>
  <ping_protocol>HTTP</ping_protocol>
  <ping_port>80</ping_port>
  <ping_path>/index.html</ping_path>
  <response_timeout>5000</response_timeout>
  <health_check_interval>3000</health_check_interval>
  <unhealthy_threshold>2</unhealthy_threshold>
  <healthy_threshold>3</healthy_threshold>
 </global_setting>
 <instances>
  <instance ip="192.168.234.121"/>
  <instance ip="192.168.234.28"/>
 </instances>
</test>
XML;

$test = new SimpleXMLElement($content);

//获得ping_protocol的值
$ping_protocol = $test->global_setting->ping_protocol;
echo "ping_protocol : $ping_protocol n";

//打印出所有instance的IP
foreach ( $test->instances->instance as $instance) {
 echo "IP: {$instance['ip']} n" ;
}

function array2xml($array, $xml = false){
    if($xml === false){
        $xml = new SimpleXMLElement('<root/>');
    }
    foreach($array as $key => $value){
        if(is_array($value)){
            array2xml($value, $xml->addChild($key));
        }else{
            $xml->addChild($key, $value);
        }
    }
    return $xml->asXML();
}
 
header('Content-type: text/xml');
print array2xml($array);

<?xml version="1.0" encoding="utf-8"?>
<phoneBook>
    <person>
        <name>吴边</name>
        <tel>13222053785</tel>
    </person>
    <person>
        <name>吴边2</name>
        <tel>15151981159</tel>
    </person>
    <person>
        <name>test</name>
        <tel>15077887624</tel>
    </person>
    <person>
        <name>撒旦发撒旦发</name>
        <tel>132423142134</tel>
    </person>
    <person>
        <name>阿斯顿飞</name>
        <tel>1234123421342134</tel>
    </person>
</phoneBook>

$doc=new DOMDocument("1.0","utf-8");  #声明文档类型
$doc->formatOutput=true;              #设置可以输出操作
#声明根节点，最好一个XML文件有个跟节点
$root=$doc->createElement("phoneBook");#创建节点对象实体
$doc->appendChild($root);            #把节点添加进来
  
$person=$doc->createElement("person");  #创建节点对象实体  
$root->appendChild($person);    #把节点添加到root节点的子节点
  
$contactName=$doc->createElement("name");
$person->appendChild($contactName);
  
$contactNum=$doc->createElement("tel");
$person->appendChild($contactNum);
  
$contactName->appendChild($doc->createTextNode($name));
$contactNum->appendChild($doc->createTextNode($tel));
  
$doc->save($filename); #保存路径

$doc = new DOMDocument();  #声明文档类型
$doc -> load($filename);
$root = $doc->getElementsByTagName("phoneBook")->item(0);
      
$person = $doc->createElement("person");
  
$contactName = $doc->createElement("name");
$contactName->nodeValue = $name;
  
$contactNum = $doc->createElement("tel");
$contactNum->nodeValue = $tel;
  
$person -> appendChild($contactName);
$person -> appendChild($contactNum);
$root -> appendChild($person);
$doc->save($filename); #保存路径

$xmldoc = new DOMDocument();
$xmldoc -> load("contacts.xml");
$root = $xmldoc->getElementsByTagName("person");
  
foreach($root as $v){
    echo $v->getElementsByTagName("name")->item(0)->nodeValue."<br/>";
}

<?php
$file = "xmltest.xml";
//验证文件的合法性
function trustedFile($file) {
    // only trust local files owned by ourselves
    if (!eregi("^([a-z]+)://", $file)
        && fileowner($file) == getmyuid()) {
            return true;
    }
    return false;
}
//处理起始标记的函数。用特殊颜色标记并输出显示。
//注意$attribs为数组
function startElement($parser, $name, $attribs=array() ) {
    print "&lt;<font color="#0000cc">$name</font>";
    if (sizeof($attribs)) {
        while (list($k, $v) = each($attribs)) {
            print " <font color="#009900">$k</font>="<font
                   color="#990000">$v</font>"";
        }
    }
    print "&gt;";
}
//结束标记处理并显示
function endElement($parser, $name) {
    print "&lt;/<font color="#0000cc">$name</font>&gt;";
}
//处理数据部分
function characterData($parser, $data) {
    print "<b>$data</b>";
}
//处理指令（PI）处理器 参数处理函数
function PIHandler($parser, $target, $data) {
    switch (strtolower($target)) {
        case "php":
            global $parser_file;
            // If the parsed document is "trusted", we say it is safe
            // to execute PHP code inside it.  If not, display the code
            // instead.
            if (trustedFile($parser_file[$parser])) {
                eval($data);
            } else {
                printf("Untrusted PHP code: <i>%s</i>",
                        htmlspecialchars($data));
            }
            break;
    }
}
//默认处理句柄
function defaultHandler($parser, $data) {
    if (substr($data, 0, 1) == "&" && substr($data, -1, 1) == ";") {//判断数据是否为外部实体，注意这种判断方法。
        printf('<font color="#aa00aa">%s</font>',
                htmlspecialchars($data));
    } else {
        printf('<font size="-1">%s</font>',
                htmlspecialchars($data));
    }
}
//外部实体处理句柄
function externalEntityRefHandler($parser, $openEntityNames, $base, $systemId,$publicId) {
    if ($systemId) {
        if (!list($parser, $fp) = new_xml_parser($systemId)) {
            printf("Could not open entity %s at %sn", $openEntityNames,
                   $systemId);
            return false;
        }
        while ($data = fread($fp, 4096)) {
            if (!xml_parse($parser, $data, feof($fp))) {
                printf("XML error: %s at line %d while parsing entity %sn",
                       xml_error_string(xml_get_error_code($parser)),
                       xml_get_current_line_number($parser), $openEntityNames);
                xml_parser_free($parser);
                return false;
            }
        }
        xml_parser_free($parser);
        return true;
    }
    return false;
}
//xml分析器。
function new_xml_parser($file) {
    global $parser_file;
    $xml_parser = xml_parser_create(); //建立一个 XML 解析器，此函数返回解释器的操作句柄。
    xml_parser_set_option($xml_parser, XML_OPTION_CASE_FOLDING, 1); //设置是否采用大小写折叠，及目标编码
    xml_set_element_handler($xml_parser, "startElement", "endElement");//建立起始和终止元素处理器，bool
    xml_set_character_data_handler($xml_parser, "characterData");//建立字符数据处理器,bool
    xml_set_processing_instruction_handler($xml_parser, "PIHandler");//建立处理指令（PI）处理器
    xml_set_default_handler($xml_parser, "defaultHandler"); //默认处理器
    xml_set_external_entity_ref_handler($xml_parser, "externalEntityRefHandler");//外部实体指向处理器
  
    if (!($fp = @fopen($file, "r"))) {
        return false;
    }
    if (!is_array($parser_file)) {
        settype($parser_file, "array");//将文件处理变量设为array类型
    }
    $parser_file[$xml_parser] = $file; //？将文件名赋值给以解释器操作句柄为索引的数组？(解释器的句柄以资源记录的形式返回)
//    echo "<font color=red >parser = ";
//    print_r($parser_file);
//    echo "<br>$xml_parser";
//    echo "</font>";
    return array($xml_parser, $fp); //解释器的操作句柄 和待分析文件的句柄
}
if (!(list($xml_parser, $fp) = new_xml_parser($file))) {
    die("could not open XML input");
}
print "<pre>";
while ($data = fread($fp, 4096)) {
    if (!xml_parse($xml_parser, $data, feof($fp))) {//此处采用条件赋值。当条件表达式失效时执行if处理，否则跳过。
        die(sprintf("XML error: %s at line %dn",
                    xml_error_string(xml_get_error_code($xml_parser)),
                    xml_get_current_line_number($xml_parser)));
    }
}
print "</pre>";
print "parse completen";
xml_parser_free($xml_parser);
?>
 
xmltest.xml文件
<?xml version="1.0" encoding="UTF-8" ?>
<!--因为对xml了解不是很深，故将实体引用部分略去了 -->
<chapter>
 <TITLE>Title </TITLE>
 <para>
  <informaltable>
   <tgroup cols="3">
    <tbody>
     <row><entry>a1</entry><entry morerows="1">b1</entry><entry>c1</entry></row>
     <row><entry>a2</entry><entry>c2</entry></row>
     <row><entry>a3</entry><entry>b3</entry><entry>c3</entry></row>
    </tbody>
   </tgroup>
  </informaltable>
 </para>
 <section id="about">
  <title>About this Document</title>
  <para>
   <!-- this is a comment -->
   <?php print 'Hi!  This is PHP version '.phpversion(); ?>
  </para>
 </section>
 </chapter>
 
 
还有一个是将xml文件处理成php数组的例子。
<?php
class AminoAcid {
    var $name;  // aa name
    var $symbol;    // three letter symbol
    var $code;  // one letter code
    var $type;  // hydrophobic, charged or neutral
  
    function AminoAcid ($aa) {
        foreach ($aa as $k=>$v)
            $this->$k = $aa[$k];
    }
}
function readDatabase($filename) {
    // read the xml database of aminoacids
    $data = implode("",file($filename));//首先将整篇文章读入数组，之后再将数组连接成字符串，赋值给$data.
    $parser = xml_parser_create();
    xml_parser_set_option($parser,XML_OPTION_CASE_FOLDING,0);//不使用大小写折叠
    xml_parser_set_option($parser,XML_OPTION_SKIP_WHITE,1);
    xml_parse_into_struct($parser,$data,$values,$tags);//将 XML 数据解析到数组中，该函数将 XML 文件解析到两个对应的数组中，
                //$tags 参数含有指向 $values 数组中对应值的指针。最后两个数组参数可由指针传递给函数。
    xml_parser_free($parser);
    // loop through the structures
    //针对具体的应用(不同的xml文件，修改此处循环结构得到具体的数组即可。
    foreach ($tags as $key=>$val) {
        if ($key == "molecule") {
            $molranges = $val;
            // each contiguous pair of array entries are the
            // lower and upper range for each molecule definition
            for ($i=0; $i < count($molranges); $i+=2) {
                    $offset = $molranges[$i] + 1;
                $len = $molranges[$i + 1] - $offset;
                $tdb[] = parseMol(array_slice($values, $offset, $len));
            }
        } else {
            continue;
        }
    }
//    echo "<font color=red>values is:";
//    print_r($values);
//    echo "</font>";
    return array($tdb,$values);
}
function parseMol($mvalues) {
    for ($i=0; $i < count($mvalues); $i++)
        $mol[$mvalues[$i]["tag"]] = $mvalues[$i]["value"];
      
//    echo "<font color=blue> after parsemol :";
//    print_r($mol);
//    echo "</font>";
    return new AminoAcid($mol);
}
$db = readDatabase("moldb.xml");
echo "** Database of AminoAcid objects:n";
   // echo "<font color=purple> readdatabase :";
    print_r($db[0]);
   // echo "</font>";

$s = parseMol($db[1]);
?>
 
副 moldb.xml
<?xml version="1.0" encoding="UTF-8" ?>
<moldb>
    <molecule>
        <name>Alanine</name>
        <symbol>ala</symbol>
        <code>A</code>
        <type>hydrophobic</type>
    </molecule>
    <molecule>
        <name>Lysine</name>
        <symbol>lys</symbol>
        <code>K</code>
        <type>charged</type>
    </molecule>
</moldb>

stdClass Object ( [$t] => 2011-12-12T13:00:00.000Z )

$t = $feed->item->{'$t'};