在文章“如何在ASP.NET Web API中使用FastReport.Net”中，我們已經(jīng)討論了如何創(chuàng)建一個用于生成報表的Web服務(wù)。然后我們會收到報表的鏈接，現(xiàn)在我們來看看如何獲??取報表并使用ajax腳本顯示它。

讓我提醒你一下，我們的服務(wù)可以返回以這些格式之一導(dǎo)出的報表：PDF、HTML、PNG。我們將以HTML格式接收報表，并使用ajax腳本將其顯示在網(wǎng)頁上。

我們接下來講解一下從頭開始創(chuàng)建WebApi應(yīng)用程序的過程。首先，創(chuàng)建一個ASP.Net應(yīng)用程序，WebAPI。選擇空模板并勾選選項：MVC和WebApi。

在項目引用中，添加FastReport.dll庫。

我們繼續(xù)創(chuàng)建一個數(shù)據(jù)模型。現(xiàn)在Model文件夾是空的。點擊右鍵并選擇“Add”，“Class”。

將其命名為Reports.cs。添加兩個字段：Id和ReportName：

namespace FastReportWebApiDemo.Models
{
 public class Reports
 {
 // Report ID
 public int Id { get; set; }
 // Report File Name
 public string ReportName { get; set; }
 }
}

你需要將報表模板和數(shù)據(jù)庫文件放在App_Data文件夾中。在我們的例子中，我們把這兩個報表放進去：“Simple List.frx”和“Barcode.frx”；

現(xiàn)在，在Controllers文件夾中，添加控制器ReportsController。它將包含應(yīng)用程序的所有邏輯。我們使用Controllers文件夾的上下文菜單執(zhí)行此操作。選擇“添加” - >“控制器“：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using FastReport;
using FastReport.Export.Image;
using FastReport.Export.Html;
using FastReport.Export.Pdf;
using FastReport.Utils;
using FastReportWebApiDemo.Models;
using System.Web.Hosting;
using System.Data;
using System.IO;
using System.Net.Http.Headers;
 
namespace FastReportWebApiDemo.Controllers
{
// Transfer class with parameters for requesting a report
 public class ReportQuery
 {
 // Format of resulting report: png, pdf, html
 public string Format { get; set; }
 // Value of "Parameter" variable in report
 public string Parameter { get; set; }
 // Enable Inline preview in browser (generates "inline" or "attachment")
 public bool Inline { get; set; }
 }
 
 public class ReportsController : ApiController
 { //Reports list
 Reports[] reportItems = new Reports[]
 {
 new Reports { Id = 1, ReportName = "Simple List.frx" },
 new Reports { Id = 2, ReportName = "Barcode.frx" }
 };
 
 // Get list of reports
 public IEnumerable<Reports> GetAllReports()
 {
 return reportItems;
 }
 
 // Get report by ID from request
 public HttpResponseMessage GetReportById(int id, [FromUri] ReportQuery query)
 {
 // Find report
 Reports reportItem = reportItems.FirstOrDefault((p) => p.Id == id);
 if (reportItem != null)
 {
 string reportPath = HostingEnvironment.MapPath("~/App_Data/" + reportItem.ReportName);
 string dataPath = HostingEnvironment.MapPath("~/App_Data/nwind-employees.xml");
 MemoryStream stream = new MemoryStream();
 try
 {
 using (DataSet dataSet = new DataSet())
 {
// Fill the data source with the data
 dataSet.ReadXml(dataPath);
// Enable FastReport web mode
 Config.WebMode = true;
 using (Report report = new Report())
 {
 report.Load(reportPath); // Load the report
 report.RegisterData(dataSet, "NorthWind"); // Register the data in the report
 if (query.Parameter != null)
 {
 report.SetParameterValue("Parameter", query.Parameter); // Set the value of the parameter in the report. The very meaning we take from the URL
 }
 
 // Two phases of preparation to exclude the display of any dialogs
 report.PreparePhase1();
 report.PreparePhase2();
 
 if (query.Format == "pdf")
 {
// Export the report to PDF
 PDFExport pdf = new PDFExport();
// We use the stream to store the report so that we do not produce files
 report.Export(pdf, stream);
 }
 else if (query.Format == "html")
 {
// Export the report to HTML
 HTMLExport html = new HTMLExport();
 html.SinglePage = true;
 html.Navigator = false;
 html.EmbedPictures = true;
 report.Export(html, stream);
 }
 else if (query.Format == "png")
 {
// Export the report to PNG
 using (ImageExport img = new ImageExport())
 {
 img.ImageFormat = ImageExportFormat.Png;
 img.SeparateFiles = false;
 img.ResolutionX = 96;
 img.ResolutionY = 96;
 report.Export(img, stream);
 query.Format = "png";
 }
 }
 else
 {
 WebReport webReport = new WebReport();// Create a report object
 webReport.Report.Load(reportPath); // Load the report
 webReport.Report.RegisterData(dataSet, "NorthWind"); // Register the data source in the report
 if (query.Parameter != null)
 {
 webReport.Report.SetParameterValue("Parameter", query.Parameter); // Set the value of the report parameter
 }
 // inline registration of FastReport javascript
 webReport.InlineRegistration = true; // Allows you to register scripts and styles in the body of the html-page instead of placing them in the title
 webReport.Width = Unit.Percentage(100);
 webReport.Height = Unit.Percentage(100);
 // get control
 HtmlString reportHtml = webReport.GetHtml(); // load the report into HTML
 byte[] streamArray = Encoding.UTF8.GetBytes(reportHtml.ToString());
 stream.Write(streamArray, 0, streamArray.Length); // Write the report to the stream
 } 
}
 }
// create the resulting variable
 HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK)
 {
 Content = new ByteArrayContent(stream.ToArray())
 };
 
 stream.Dispose();
 
 result.Content.Headers.ContentDisposition =
 new System.Net.Http.Headers.ContentDispositionHeaderValue(query.Inline ? "inline" : "attachment")
 {
// Set the file extension depending on the type of export
 FileName = String.Concat(Path.GetFileNameWithoutExtension(reportPath), ".", query.Format)
 };
// Define the content type for the browser
result.Content.Headers.ContentType =
 new MediaTypeHeaderValue("application/" + query.Format);
 return result;
 }
// Handle Exceptions
 catch
 {
 return new HttpResponseMessage(HttpStatusCode.InternalServerError);
 }
 }
 else
 return new HttpResponseMessage(HttpStatusCode.NotFound);
 }
 }
}

在ReportsController類中，我們創(chuàng)建了一個報表數(shù)組和兩個方法。名稱和報表標識符在數(shù)組中定義。GetAllReports () 方法返回可用報表的列表。第二種方法 GetReportById (int id, [FromUri] ReportQuery query) 通過標識符返回一個報表。從查詢屬性中，我們可以得到參數(shù)格式、內(nèi)聯(lián)和參數(shù)。這三者分別決定：報表的導(dǎo)出格式，報表是否會直接在瀏覽器中打開，傳遞給報表的參數(shù)的值。特別有趣的是 webReport.GetHtml () 方法，它可以讓你獲得報表的HTML視圖。這就是我們使用ajax在頁面上顯示的內(nèi)容。

在Web.config文件中，你需要添加兩個處理句柄：

<handlers>
… 
<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
 <add name="FastReportHandler" path="FastReport.Export.axd" verb="*" type="FastReport.Web.Handlers.WebExport" />
…
</handlers>

現(xiàn)在添加網(wǎng)頁。在項目上點擊右鍵并選擇Add-> HTML Page。

一般我們習慣將起始頁命名為Index。將以下代碼添加到頁面中：

<!DOCTYPE html>
<html>
<head>
 <title></title>
 <meta charset="utf-8" />
 <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js"></script>
</head>
<body>
 <script type="text/javascript" language="javascript">
 function call() {
 var msg = $('#formx').serialize();
 $.ajax({ 
 type: 'GET',// Type
 url: '//localhost:58005/api/reports/1', // We receive a file from Rest service
 cache: false,// Caching
 timeout: 30000,// Timeout
 data: msg,
 success: function (data) {// The function will work if the data is successfully received
 $('#results').html(data);// We display the data in the form },
 beforeSend: function (data) {// The function is activated during the waiting period of data
 $('#results').html('<p> Waiting for data...</p>');
 },
 dataType: "html", // Data type 
 error: function (data) {// Function will work if an error occurs
 $('#results').html('<p> Failed to load report</p>');
 }
 });
 }
 </script>
<form method="GET" id="formx" action="javascript:void(null);" onsubmit="call()">
 <input value="Загрузить" type="submit">
 </form>
 <div id="results" typeof="submit"></div><!-- Here the result will be displayed-->
</body>
</html>

從代碼中可以看到，我們只是通過從服務(wù)鏈接請求來加載HTML報表文件。

從文件夾App_Start打開文件WebApiConfig.cs。為Index頁面添加一個MapHttpRoute：

public static void Register(HttpConfiguration config)
 {
 // Web API configuration and services
 // Web API routes
 config.MapHttpAttributeRoutes();
 config.Routes.MapHttpRoute(
 name: "Index",
 routeTemplate: "{id}.html",
 defaults: new { id = "index" }
 );
 
 config.Routes.MapHttpRoute(
 name: "DefaultApi",
 routeTemplate: "api/{controller}/{id}",
 defaults: new { id = RouteParameter.Optional }
 );
 }

在同一個文件夾中，找到RouteConfig.cs文件。它可以被刪除。

打開文件Global.asax。刪除該行： 

RouteConfig.RegisterRoutes(RouteTable.Routes); 

現(xiàn)在路由只能通過WebApiConfig來完成。

運行該應(yīng)用程序，然后單擊“下載”按鈕：

就這樣，我們收到了報表。

從上面的例子可以清楚的看出，使用Ajax進行報表處理是非常簡單的。

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