[英]In C#, how can I parse out a url from a html page that I have got using webproxy.load()?
[英]How to parse JSON URL Page by Page using C#
我是C#和JSON的新手。 我正在尝试解析一个JSON URL,该URL的请求限制为每页100个对象。 即使21页中有2022个对象,我也无法检索包含100个对象的第一页之外的页面。
我的代码中缺少哪些内容来允许解析所有22页的JSON对象?
谢谢您提前提供的所有帮助!
对象的总数由HTTP响应标头给出: X-Total-Count
public class VCUtils
{
public const string HeaderRateLimit = "X-Rate-Limit-Limit";
public const string HeaderRateRemaining = "X-Rate-Limit-Remaining";
public const string HeaderRateReset = "X-Rate-Limit-Reset";
public const string HeaderCountTotal = "X-Total-Count";
}
以下是我的测试代码。
protected void Page_Load(object sender, EventArgs e)
{
string baseURL = "https://api.veracross.com/vcdemo3/v2/students.json?page=";
int recordcount = 1;
int nextPage = 1;
int totalObjectCount = 0;
int defaultObjectsPerPage = 100;
int pageCount = 1000;
try
{
while (nextPage <= pageCount) //pageCount
{
string jsonData = "";
var req = (HttpWebRequest)WebRequest.Create(baseURL + nextPage);
req.Credentials = new NetworkCredential(vcAPIUsername, vcAPIPassword);
req.PreAuthenticate = true;
HttpWebResponse response = req.GetResponse() as HttpWebResponse;
using (var reader = new System.IO.StreamReader(response.GetResponseStream())) { jsonData = reader.ReadToEnd(); }
// get total number of objects and calculate the page count
if (response.Headers[VCUtils.HeaderCountTotal] != null)
{
totalObjectCount = Convert.ToInt16(response.Headers[VCUtils.HeaderCountTotal]);
pageCount = (int)Math.Ceiling((double)totalObjectCount / (double)defaultObjectsPerPage);
}
VCStudents studentObj = new VCStudents();
IList<VCStudents> validStudents;
// Call the JSON.NET deserializer helper method
validStudents = VCUtils.DeserializeToList<VCStudents>(jsonData);
foreach (var item in validStudents)
{
var studs = item.GetType().GetProperties();
//**
int stkey = item.person_pk; //possibly legacy fields
string surname = item.last_name;
string first_name = item.first_name;
string pref_name = item.preferred_name;
string st_mobile = item.mobile_phone;
string st_email = item.email_1;
int gsis_id = item.person_pk;
string birthdate = item.birthday;
string gender = item.gender;
string lastupdatedate = item.update_date;
var fdkey = item.first_name;
Literal1.Text = Literal1.Text + recordcount + ") " + stkey + " " + surname + " " + first_name + " " + pref_name + " " + st_mobile + " " + st_email + " " + gsis_id + " " + birthdate + " " + roll_group + " " + gender + " " + fdkey + " " + lastupdatedate + "</br> ";
recordcount = recordcount + 1;
}
nextPage = nextPage + 1;
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
}
}
以下是http://www.cshandler.com/2013/09/deserialize-list-of-json-objects-as.html#.WPguVUWGOJA引用的JsonHelper方法
public static List<string> InvalidJsonElements;
public static IList<T> DeserializeToList<T>(string jsonString)
{
InvalidJsonElements = null;
var array = JArray.Parse(jsonString);
IList<T> objectsList = new List<T>();
foreach (var item in array)
{
try
{
// CorrectElements
objectsList.Add(item.ToObject<T>());
}
catch (Exception ex)
{
InvalidJsonElements = InvalidJsonElements ?? new List<string>();
InvalidJsonElements.Add(item.ToString());
}
}
return objectsList;
}
以下是在json2csharp.com上生成的类
public class VCStudentRole
{
public string description { get; set; }
}
public class VCStudents
{
public const string studentsBasePath = "students";
public int household_fk { get; set; }
public int person_pk { get; set; }
public string name_prefix { get; set; }
public string first_name { get; set; }
public string first_nick_name { get; set; }
public string preferred_name { get; set; }
public string middle_name { get; set; }
public string last_name { get; set; }
public string name_suffix { get; set; }
public string birthday { get; set; }
public string gender { get; set; }
public string email_1 { get; set; }
public bool display_email_1 { get; set; }
public string email_2 { get; set; }
public bool display_email_2 { get; set; }
public string home_phone { get; set; }
public bool display_home_phone { get; set; }
public string mobile_phone { get; set; }
public bool display_mobile_phone { get; set; }
public int advisor_fk { get; set; }
public string advisor_name { get; set; }
public int homeroom_teacher_fk { get; set; }
public string homeroom_teacher_name { get; set; }
public int homeroom { get; set; }
public List<VCStudentRole> roles { get; set; }
public string current_grade { get; set; }
public string grade_applying_for { get; set; }
public int year_applying_for { get; set; }
public bool resident_status_applying_for { get; set; }
public bool student_group_applying_for { get; set; }
public bool campus_applying_for { get; set; }
public string school_level { get; set; }
public string enrollment_status { get; set; }
public bool new_student { get; set; }
public int graduation_year { get; set; }
public string resident_status { get; set; }
public string campus { get; set; }
public string dorm { get; set; }
public string room_number { get; set; }
public int floor_number { get; set; }
public int bed_number { get; set; }
public string mailbox_number { get; set; }
public string student_group { get; set; }
public int parent_1_fk { get; set; }
public int parent_2_fk { get; set; }
public int parent_3_fk { get; set; }
public int parent_4_fk { get; set; }
public string username { get; set; }
public string update_date { get; set; }
}
我怀疑您是否可以通过以下代码获得准确的总数:
totalObjectCount = Convert.ToInt16(response.Headers[VCUtils.HeaderCountTotal]);
您可以尝试以下方法:
totalObjectCount = Convert.ToInt32(response.Headers.Get(VCUtils.HeaderCountTotal));
从MSDN中查看更多详细信息: https : //msdn.microsoft.com/zh-cn/library/system.net.webheadercollection(v= vs.110) .aspx
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