ajax调用返回php接口返回json数据

php代码如下：

<?php

    header("Content-Type: application/json");
    header("Content-Type: text/html;charset=utf-8");

    $email = $_GET["email"];

    $user = [];

    $conn = @mysql_connect("localhost","Test","123456") or die("Failed in connecting database");
    mysql_select_db("Test",$conn);
    mysql_query("set names "UTF-8"");
    $query = "select * from UserInformation where email = "".$email.""";
    $result = mysql_query($query);
    if (null == ($row = mysql_fetch_array($result))) {
        echo $_GET["callback"]."(no such user)";
    } else {
        $user["email"] = $email;
        $user["nickname"] = $row["nickname"];
        $user["portrait"] = $row["portrait"];
        echo $_GET["callback"]."(".json_encode($user).")";
    }

?>

js代码如下:

<script>
        $.ajax({
            url: "http://test.localhost/UserInterfaceForChatroom/UserInformation.php?email=pshuyue@gmail.com",
            type: "GET",
            dataType: "jsonp",
            //            crossDomain: true,
            success: function (result) {
                //                data = $.parseJSON(result);
                //                alert(data.nickname);
                alert(result.nickname);
            }
        });
    </script>

其中遇到了两个问题:

1.第一个问题:

解决方案如下:

This has just happened to me, and the reason was none of the reasons above. I was using the jQuery command getJSON and adding callback=? to use JSONP (as I needed to go cross-domain), and returning the JSON code {"foo":"bar"} and getting the error.

This is because I should have included the callback data, something like jQuery17209314005577471107_1335958194322({"foo":"bar"})

Here is the PHP code I used to achieve this, which degrades if JSON (without a callback) is used:

$ret["foo"] = "bar";
finish();

function finish() {
    header("content-type:application/json");
    if ($_GET["callback"]) {
        print $_GET["callback"]."(";
    }
    print json_encode($GLOBALS["ret"]);
    if ($_GET["callback"]) {
        print ")";
    }
    exit; 
}

Hopefully that will help someone in the future.

2.第二个问题: 解析json数据。从上面的javascript中可以看到，我没有使用jquery.parseJSON()这些方法，开始使用这些方法，但是总是会报 VM219:1 Uncaught SyntaxError: Unexpected token o in JSON at position 1 的错误，后来不用jquery.parseJSON()这个方法，反而一切正常。不知为何。