1.使用ViewData
ViewData 的是ControllerBase 的一个属性,是一个数据字典类型的，其实现代码如(这段代码来自asp.net MVC开源项目中源码)下:
Code1 public class ViewDataDictionary : IDictionary<string, object> {
2
3 private readonly Dictionary<string, object> _innerDictionary = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
4 private object _model;
5 private readonly ModelStateDictionary _modelState = new ModelStateDictionary();
6
7 public ViewDataDictionary()
8 : this((object)null) {
9 }
10
11 [SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors",
12 Justification = "See note on SetModel() method.")]
13 public ViewDataDictionary(object model) {
14 Model = model;
15 }
16
17 [SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors",
18 Justification = "See note on SetModel() method.")]
19 public ViewDataDictionary(ViewDataDictionary dictionary) {
20 if (dictionary == null) {
21 throw new ArgumentNullException("dictionary");
22 }
23
24 foreach (var entry in dictionary) {
25 _innerDictionary.Add(entry.Key, entry.Value);
26 }
27 foreach (var entry in dictionary.ModelState) {
28 ModelState.Add(entry.Key, entry.Value);
29 }
30 Model = dictionary.Model;
31 }
32
33 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]
34 public int Count {
35 get {
36 return _innerDictionary.Count; 37 } 38 } 39 40 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")] 41 public bool IsReadOnly { 42 get { 43 return ((IDictionary<string, object>)_innerDictionary).IsReadOnly; 44 } 45 } 46 47 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")] 48 public ICollection<string> Keys { 49 get { 50 return _innerDictionary.Keys; 51 } 52 } 53 54 public object Model { 55 get { 56 return _model; 57 } 58 set { 59 SetModel(value); 60 } 61 } 62 63 public ModelStateDictionary ModelState { 64 get { 65 return _modelState; 66 } 67 } 68 69 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")] 70 public object this[string key] { 71 get { 72 object value; 73 _innerDictionary.TryGetValue(key, out value); 74 return value; 75 } 76 set { 77 _innerDictionary[key] = value; 78 } 79 } 80 81 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")] 82 public ICollection<object> Values { 83 get { 84 return _innerDictionary.Values; 85 } 86 } 87 88 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")] 89 public void Add(KeyValuePair<string, object> item) { 90 ((IDictionary<string, object>)_innerDictionary).Add(item); 91 } 92 93 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")] 94 public void Add(string key, object value) { 95 _innerDictionary.Add(key, value); 96 } 97 98 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")] 99 public void Clear() {100 _innerDictionary.Clear();101 }102 103 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]104 public bool Contains(KeyValuePair<string, object> item) {105 return ((IDictionary<string, object>)_innerDictionary).Contains(item);106 }107 108 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]109 public bool ContainsKey(string key) {110 return _innerDictionary.ContainsKey(key);111 }112 113 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]114 public void CopyTo(KeyValuePair<string, object>[] array, int arrayIndex) {115 ((IDictionary<string, object>)_innerDictionary).CopyTo(array, arrayIndex);116 }117 118 [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Eval",119 Justification = "Commonly used shorthand for Evaluate.")]120 public object Eval(string expression) {121 if (String.IsNullOrEmpty(expression)) {122 throw new ArgumentException(MvcResources.Common_NullOrEmpty, "expression");123 }124 125 return ViewDataEvaluator.Eval(this, expression);126 }127 128 [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Eval",129 Justification = "Commonly used shorthand for Evaluate.")]130 public string Eval(string expression, string format) {131 object value = Eval(expression);132 133 if (value == null) {134 return String.Empty;135 }136 137 if (String.IsNullOrEmpty(format)) {138 return Convert.ToString(value, CultureInfo.CurrentCulture);139 }140 else {141 return String.Format(CultureInfo.CurrentCulture, format, value);142 }143 }144 145 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]146 public IEnumerator<KeyValuePair<string, object>> GetEnumerator() {147 return _innerDictionary.GetEnumerator();148 }149 150 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]151 public bool Remove(KeyValuePair<string, object> item) {152 return ((IDictionary<string, object>)_innerDictionary).Remove(item);153 }154 155 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]156 public bool Remove(string key) {157 return _innerDictionary.Remove(key);158 }159 160 // This method will execute before the derived type's instance constructor executes. Derived types must161 // be aware of this and should plan accordingly. For example, the logic in SetModel() should be simple162 // enough so as not to depend on the "this" pointer referencing a fully constructed object.163 protected virtual void SetModel(object value) {164 _model = value;165 }166 167 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]168 public bool TryGetValue(string key, out object value) {169 return _innerDictionary.TryGetValue(key, out value);170 }171 172 internal static class ViewDataEvaluator {173 public static object Eval(ViewDataDictionary vdd, string expression) {174 //Given an expression "foo.bar.baz" we look up the following (pseudocode):175 // this["foo.bar.baz.quux"]176 // this["foo.bar.baz"]["quux"]177 // this["foo.bar"]["baz.quux]178 // this["foo.bar"]["baz"]["quux"]179 // this["foo"]["bar.baz.quux"]180 // this["foo"]["bar.baz"]["quux"]181 // this["foo"]["bar"]["baz.quux"]182 // this["foo"]["bar"]["baz"]["quux"]183 184 object evaluated = EvalComplexExpression(vdd, expression);185 return evaluated;186 }187 188 private static object EvalComplexExpression(object indexableObject, string expression) {189 foreach (ExpressionPair expressionPair in GetRightToLeftExpressions(expression)) {190 string subExpression = expressionPair.Left;191 string postExpression = expressionPair.Right;192 193 object subtarget = GetPropertyValue(indexableObject, subExpression);194 if (subtarget != null) {195 if (String.IsNullOrEmpty(postExpression))196 return subtarget;197 198 object potential = EvalComplexExpression(subtarget, postExpression);199 if (potential != null) {200 return potential;201 }202 }203 }204 return null;205 }206 207 private static IEnumerable<ExpressionPair> GetRightToLeftExpressions(string expression) {208 // Produces an enumeration of all the combinations of complex property names209 // given a complex expression. See the list above for an example of the result210 // of the enumeration.211 212 yield return new ExpressionPair(expression, String.Empty);213 214 int lastDot = expression.LastIndexOf('.');215 216 string subExpression = expression;217 string postExpression = string.Empty;218 219 while (lastDot > -1) {220 subExpression = expression.Substring(0, lastDot);221 postExpression = expression.Substring(lastDot + 1);222 yield return new ExpressionPair(subExpression, postExpression);223 224 lastDot = subExpression.LastIndexOf('.');225 }226 }227 228 private static object GetIndexedPropertyValue(object indexableObject, string key) {229 Type indexableType = indexableObject.GetType();230 231 ViewDataDictionary vdd = indexableObject as ViewDataDictionary;232 if (vdd != null) {233 return vdd[key];234 }235 236 MethodInfo containsKeyMethod = indexableType.GetMethod("ContainsKey", BindingFlags.Public | BindingFlags.Instance, null, new Type[] { typeof(string) }, null);237 if (containsKeyMethod != null) {238 if (!(bool)containsKeyMethod.Invoke(indexableObject, new object[] { key })) {239 return null;240 }241 }242 243 PropertyInfo info = indexableType.GetProperty("Item", BindingFlags.Public | BindingFlags.Instance, null, null, new Type[] { typeof(string) }, null);244 if (info != null) {245 return info.GetValue(indexableObject, new object[] { key });246 }247 248 PropertyInfo objectInfo = indexableType.GetProperty("Item", BindingFlags.Public | BindingFlags.Instance, null, null, new Type[] { typeof(object) }, null);249 if (objectInfo != null) {250 return objectInfo.GetValue(indexableObject, new object[] { key });251 }252 return null;253 }254 255 private static object GetPropertyValue(object container, string propertyName) {256 // This method handles one "segment" of a complex property expression257 258 // First, we try to evaluate the property based on its indexer259 object value = GetIndexedPropertyValue(container, propertyName);260 if (value != null) {261 return value;262 }263 264 // If the indexer didn't return anything useful, continue265 266 // If the container is a ViewDataDictionary then treat its Model property267 // as the container instead of the ViewDataDictionary itself.268 ViewDataDictionary vdd = container as ViewDataDictionary;269 if (vdd != null) {270 container = vdd.Model;271 }272 273 // Second, we try to use PropertyDescriptors and treat the expression as a property name274 PropertyDescriptor descriptor = TypeDescriptor.GetProperties(container).Find(propertyName, true);275 if (descriptor == null) {276 return null;277 }278 279 return descriptor.GetValue(container);280 }281 282 private struct ExpressionPair {283 public readonly string Left;284 public readonly string Right;285 286 public ExpressionPair(string left, string right) {287 Left = left;288 Right = right;289 }290 }291 }292 293 #region IEnumerable Members294 [SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase")]295 IEnumerator IEnumerable.GetEnumerator() {296 return ((IEnumerable)_innerDictionary).GetEnumerator();297 }298 #endregion299 300 }
ViewData的用法如下:ViewData["user"] = LoginUser; 页面的代码<%=(ViewData["user"] as Users).UserName%>
ViewData的作用域从控制器设置值到页面值显示。
2.使用TempData
TempData同样属于ControllerBase 的属性 用法和ViewData 基本相同，但是他们的实质是不同的，ViewData 是数据字典类型而TempData是Session存储的值，TempData数据只能在控制器中传递一次，每个元素也只能被访问一次，然后Session中的值就会被自动删除，它的生命周期要比ViewData的要长.
3.使用Model
使用Model 顾名思义就是将一个实体对象绑定在页面上，上面两种都是放在作用域中。这里只讲用法。
public ActionResult Student()
{
DbContext context=new DbContext();
Student stu=context.Single(s=>s.ID==1);
return View(stu);
}
页面代码的使用：<%=(Model as MVCTest.Models.Student).Name %> Model 是ViewPage d的一个属性值，用于 接收控制器中返回的值
Model 传输数据还可以这样用：
<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<MVCTest.Models.Student>" %>
<%=Model.Name %>
使用泛型的ViewPage，将Model中的值指定特定类型不用强制性转换
4.传递多个对象类型
其实传递多个对象类型，最简单的办法就是将这些对象封装成另外一个类的属性，然后将这个对象传递到页面。不在做介绍