!DOCTYPE html>
html lang="en">
head>
  meta charset="UTF-8">
  title>ajax解决跨域问题/title>
  script src="jquery-3.0.0.min.js" type="text/javascript">/script>
/head>
body>
script>
  $.ajax({
    type:"POST",
    url:"postDemo.php",
    data:{
      "url":"http://192.168.4.101:90/PHPStudy4/server.php",
      "username":"admin",
      "password":"admin",
    },success:function(data){
      var result=eval("("+data+")");
      console.log(result);
    }

  })
/script>
/body>
/html>

?php
/**
 * Created by PhpStorm.
 * User: Administrator
 * Date: 2016-7-21
 * Time: 10:12
 */

if ($_SERVER["REQUEST_METHOD"] == "POST") {
//  echo json_encode(array("111"=>"112"));
  if (isset($_POST["url"])  isset($_POST["username"])  isset($_POST["password"])) {
    $result = postDemo($_POST["url"], array("username" => $_POST["username"], "password" => $_POST["password"]));
    echo $result;

  } else {
    echo json_encode(array("msg2" => "!!!!!!!!!!!!!!!!!!!!!error!!!!!2"));
  }
} else {
  echo json_encode(array("msg" => "error!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"));
}
function postDemo($url, $data)
{

  $query = http_build_query($data);
  $options = array(
    "http" => array(
      "header" => "Content-type: application/x-www-form-urlencoded\r\n" .
        "Content-length:" . strlen($query) . "\r\n" .
        "User-Agent:MyAgent/1.0/r/n",
      "method" => "POST",
      "content" => $query
    )
  );
  $content = stream_context_create($options);
  $result = file_get_contents($url, false, $content);
  return $result;
}

//echo postDemo("http://192.168.4.101:90/PHPStudy4/server.php",array("username"=>"admin","password"=>"admin"));