Windows Phone 7常用的开发技巧&学习总结

beckham79

　　现在WP7的中文学习资料还是非常的少，自己摸索Windows Phone 7有一阵子，现在与大家分享一些自己常用技巧和个人的学习总结，同时也作为自己学习资料，用到时方便查阅，由于个人学习能力和知识有限，如果有错误或者不好之处，欢迎大家拍砖纠正，同时欢迎大家共同交流。
　　

1. ApplicationBar在其它事件中调用的方法
　　ApplicationBar控件时windows phone 7上的一个菜单，一个ApplicationBar最多可包含四个按钮。如果还有额外的选项可以通过菜单项来添加，这些菜单项默认是不显示的。只有在点击菜单栏右侧的省略号(或省略号下方的区域)时才会显示出来。它传统的Windows程序的菜单的作用类似。


    ApplicationBar相信在WP7开发的时候经常会用到，但在页面的其它控件的事件中，如果直接使用他x:Name进行调用，会出现问题....
　　假如前台代码有个ListBox里的项，我想实现点击某一项时，利用ApplicationBar有个删除按钮（appbarDelete）的删除事件进行删除，因此在未选择任何项时，默认是禁用的（IsEnabled="False"），但点击ListBox某一项激活了之后，该按钮就启用（IsEnabled="True"）。
　　ApplicationBar代码如下：
　　



   
        
            
        
   
　　
　　ListBox前台接口如下：



            
               
                    
                        
                    
               
            
　　ListBox的选中事件代码如下：



        private void messageList_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (messageList.SelectedItem != null)
            {
                appbarDelete.IsEnabled = true; //选中某项时激活ApplicationBar的删除按钮
            }
            else
            {
                appbarDelete.IsEnabled = false; //未选中时禁用ApplicationBar的删除按钮
            }
        }
　　
　　
　　点击时会出现如下异常NullReferenceException：
　　

　　
　　

这是因为ApplicationBar（ApplicationBarIconButton和ApplicationBarMenuItem）相关的类定义在Microsoft.Phone.Shell命名空间。与UIElement和FrameworkElement等常规Silverlight编程的类层次是完全分开的，严格说来ApplicationBar不是你的页面的可视化的一部分。



因此解决办法如下：
　　在Xaml构造函数初始化时，加入以下代码即可解决：
　　



        public DemoPage()
        {
            InitializeComponent();
            // Re-assign names already in the XAML file
            //解决按钮无法调用问题
            appbarDelete = this.ApplicationBar.Buttons[3] as ApplicationBarIconButton;
        }
　　注意，一般ApplicationBar有四个按钮，由于这个示例，只有一个按钮。加入上面这句代码之后，就可以解决问题，当我解决之后，点击列表某一项，就激活了删除按钮，我点击删除，就可以删除当前这项信息，如下图：

　　选中之后状态：

　　

　　

2.IsolatedStorage本地存储的封装类
　　IsolateStorage是本地存储的实现，具体介绍大家可以查阅相关资料，本次直接从微软Demo封装代码中抽取出来，具体代码如下：


View Code


// ----------------------------------------------------------------------------------
// Microsoft Developer & Platform Evangelism
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// THIS CODE AND INFORMATION ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
// EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES
// OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
// ----------------------------------------------------------------------------------
// The example companies, organizations, products, domain names,
// e-mail addresses, logos, people, places, and events depicted
// herein are fictitious.  No association with any real company,
// organization, product, domain name, email address, logo, person,
// places, or events is intended or should be inferred.
// ----------------------------------------------------------------------------------

using System.IO;
using System.IO.IsolatedStorage;
using System.Runtime.Serialization.Json;
using System.Text;
namespace Foolin.Helper
{
    public static class IsolatedStorageHelper
    {
        public static T GetObject(string key)
        {
            if (IsolatedStorageSettings.ApplicationSettings.Contains(key))
            {
                string serializedObject = IsolatedStorageSettings.ApplicationSettings[key].ToString();
                return Deserialize(serializedObject);
            }
            return default(T);
        }
        public static void SaveObject(string key, T objectToSave)
        {
            string serializedObject = Serialize(objectToSave);
            IsolatedStorageSettings.ApplicationSettings[key] = serializedObject;
        }
        public static void DeleteObject(string key)
        {
            IsolatedStorageSettings.ApplicationSettings.Remove(key);
        }
        private static string Serialize(object objectToSerialize)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                DataContractJsonSerializer serializer = new DataContractJsonSerializer(objectToSerialize.GetType());
                serializer.WriteObject(ms, objectToSerialize);
                ms.Position = 0;
                using (StreamReader reader = new StreamReader(ms))
                {
                    return reader.ReadToEnd();
                }
            }
        }
        private static T Deserialize(string jsonString)
        {
            using (MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(jsonString)))
            {
                DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T));
                return (T)serializer.ReadObject(ms);
            }
        }
    }
}
　　此外，如果你是Windows Phone OS 7.1版本的话，您需要手动添加System.Servicemodel.Web，否则你会出现未找到System.Runtime.Serialization.Json命名空间的错误。
　　

3.MD5加密的实现类
　　WP7木有提供MD5加密的方法，可是这个经常会用到，网上找了一个MD5的方法，直接上代码：



using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Text;
using System.IO;
namespace Foolin.Helper
{
public class MD5CryptoServiceProvider : MD5
{
public MD5CryptoServiceProvider()
: base()
{
}
}
///
/// Summary description for MD5.
///
public class MD5 : IDisposable
{
static public MD5 Create(string hashName)
{
if (hashName == "MD5")
return new MD5();
else
throw new NotSupportedException();
}
static public String GetMd5String(String source)
{
MD5 md = MD5CryptoServiceProvider.Create();
byte[] hash;
//Create a new instance of ASCIIEncoding to
//convert the string into an array of Unicode bytes.
UTF8Encoding enc = new UTF8Encoding();
//            ASCIIEncoding enc = new ASCIIEncoding();
//Convert the string into an array of bytes.
byte[] buffer = enc.GetBytes(source);
//Create the hash value from the array of bytes.
hash = md.ComputeHash(buffer);
StringBuilder sb = new StringBuilder();
foreach (byte b in hash)
sb.Append(b.ToString("x2"));
return sb.ToString();
}
static public MD5 Create()
{
return new MD5();
}
#region base implementation of the MD5
#region constants
private const byte S11 = 7;
private const byte S12 = 12;
private const byte S13 = 17;
private const byte S14 = 22;
private const byte S21 = 5;
private const byte S22 = 9;
private const byte S23 = 14;
private const byte S24 = 20;
private const byte S31 = 4;
private const byte S32 = 11;
private const byte S33 = 16;
private const byte S34 = 23;
private const byte S41 = 6;
private const byte S42 = 10;
private const byte S43 = 15;
private const byte S44 = 21;
static private byte[] PADDING = new byte[] {
0x80, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
#endregion
#region F, G, H and I are basic MD5 functions.
static private uint F(uint x, uint y, uint z)
{
return (((x) & (y)) | ((~x) & (z)));
}
static private uint G(uint x, uint y, uint z)
{
return (((x) & (z)) | ((y) & (~z)));
}
static private uint H(uint x, uint y, uint z)
{
return ((x) ^ (y) ^ (z));
}
static private uint I(uint x, uint y, uint z)
{
return ((y) ^ ((x) | (~z)));
}
#endregion
#region rotates x left n bits.
///
/// rotates x left n bits.
///
///
///
///
static private uint ROTATE_LEFT(uint x, byte n)
{
return (((x) > (32 - (n))));
}
#endregion
#region FF, GG, HH, and II transformations
/// FF, GG, HH, and II transformations
/// for rounds 1, 2, 3, and 4.
/// Rotation is separate from addition to prevent recomputation.
static private void FF(ref uint a, uint b, uint c, uint d, uint x, byte s, uint ac)
{
(a) += F((b), (c), (d)) + (x) + (uint)(ac);
(a) = ROTATE_LEFT((a), (s));
(a) += (b);
}
static private void GG(ref uint a, uint b, uint c, uint d, uint x, byte s, uint ac)
{
(a) += G((b), (c), (d)) + (x) + (uint)(ac);
(a) = ROTATE_LEFT((a), (s));
(a) += (b);
}
static private void HH(ref uint a, uint b, uint c, uint d, uint x, byte s, uint ac)
{
(a) += H((b), (c), (d)) + (x) + (uint)(ac);
(a) = ROTATE_LEFT((a), (s));
(a) += (b);
}
static private void II(ref uint a, uint b, uint c, uint d, uint x, byte s, uint ac)
{
(a) += I((b), (c), (d)) + (x) + (uint)(ac);
(a) = ROTATE_LEFT((a), (s));
(a) += (b);
}
#endregion
#region context info
///
/// state (ABCD)
///
uint[] state = new uint[4];
///
/// number of bits, modulo 2^64 (lsb first)
///
uint[] count = new uint[2];
///
/// input buffer
///
byte[] buffer = new byte[64];
#endregion
internal MD5()
{
Initialize();
}
///
/// MD5 initialization. Begins an MD5 operation, writing a new context.
///
///
/// The RFC named it "MD5Init"
///
public virtual void Initialize()
{
count[0] = count[1] = 0;
// Load magic initialization constants.
state[0] = 0x67452301;
state[1] = 0xefcdab89;
state[2] = 0x98badcfe;
state[3] = 0x10325476;
}
///
/// MD5 block update operation. Continues an MD5 message-digest
/// operation, processing another message block, and updating the
/// context.
///
///
///
///
/// The RFC Named it MD5Update
protected virtual void HashCore(byte[] input, int offset, int count)
{
int i;
int index;
int partLen;
// Compute number of bytes mod 64
index = (int)((this.count[0] >> 3) & 0x3F);
// Update number of bits
if ((this.count[0] += (uint)((uint)count  29);
partLen = 64 - index;
// Transform as many times as possible.
if (count >= partLen)
{
Buffer.BlockCopy(input, offset, this.buffer, index, partLen);
Transform(this.buffer, 0);
for (i = partLen; i + 63 < count; i += 64)
Transform(input, offset + i);
index = 0;
}
else
i = 0;
// Buffer remaining input
Buffer.BlockCopy(input, offset + i, this.buffer, index, count - i);
}
///
/// MD5 finalization. Ends an MD5 message-digest operation, writing the
/// the message digest and zeroizing the context.
///
/// message digest
/// The RFC named it MD5Final
protected virtual byte[] HashFinal()
{
byte[] digest = new byte[16];
byte[] bits = new byte[8];
int index, padLen;
// Save number of bits
Encode(bits, 0, this.count, 0, 8);
// Pad out to 56 mod 64.
index = (int)((uint)(this.count[0] >> 3) & 0x3f);
padLen = (index < 56) ? (56 - index) : (120 - index);
HashCore(PADDING, 0, padLen);
// Append length (before padding)
HashCore(bits, 0, 8);
// Store state in digest
Encode(digest, 0, state, 0, 16);
// Zeroize sensitive information.
count[0] = count[1] = 0;
state[0] = 0;
state[1] = 0;
state[2] = 0;
state[3] = 0;
// initialize again, to be ready to use
Initialize();
return digest;
}
///
/// MD5 basic transformation. Transforms state based on 64 bytes block.
///
///
///
private void Transform(byte[] block, int offset)
{
uint a = state[0], b = state[1], c = state[2], d = state[3];
uint[] x = new uint[16];
Decode(x, 0, block, offset, 64);
// Round 1
FF(ref a, b, c, d, x[0], S11, 0xd76aa478); /* 1 */
FF(ref d, a, b, c, x[1], S12, 0xe8c7b756); /* 2 */
FF(ref c, d, a, b, x[2], S13, 0x242070db); /* 3 */
FF(ref b, c, d, a, x[3], S14, 0xc1bdceee); /* 4 */
FF(ref a, b, c, d, x[4], S11, 0xf57c0faf); /* 5 */
FF(ref d, a, b, c, x[5], S12, 0x4787c62a); /* 6 */
FF(ref c, d, a, b, x[6], S13, 0xa8304613); /* 7 */
FF(ref b, c, d, a, x[7], S14, 0xfd469501); /* 8 */
FF(ref a, b, c, d, x[8], S11, 0x698098d8); /* 9 */
FF(ref d, a, b, c, x[9], S12, 0x8b44f7af); /* 10 */
FF(ref c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
FF(ref b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
FF(ref a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
FF(ref d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
FF(ref c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
FF(ref b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
// Round 2
GG(ref a, b, c, d, x[1], S21, 0xf61e2562); /* 17 */
GG(ref d, a, b, c, x[6], S22, 0xc040b340); /* 18 */
GG(ref c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
GG(ref b, c, d, a, x[0], S24, 0xe9b6c7aa); /* 20 */
GG(ref a, b, c, d, x[5], S21, 0xd62f105d); /* 21 */
GG(ref d, a, b, c, x[10], S22, 0x2441453); /* 22 */
GG(ref c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
GG(ref b, c, d, a, x[4], S24, 0xe7d3fbc8); /* 24 */
GG(ref a, b, c, d, x[9], S21, 0x21e1cde6); /* 25 */
GG(ref d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
GG(ref c, d, a, b, x[3], S23, 0xf4d50d87); /* 27 */
GG(ref b, c, d, a, x[8], S24, 0x455a14ed); /* 28 */
GG(ref a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
GG(ref d, a, b, c, x[2], S22, 0xfcefa3f8); /* 30 */
GG(ref c, d, a, b, x[7], S23, 0x676f02d9); /* 31 */
GG(ref b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
// Round 3
HH(ref a, b, c, d, x[5], S31, 0xfffa3942); /* 33 */
HH(ref d, a, b, c, x[8], S32, 0x8771f681); /* 34 */
HH(ref c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
HH(ref b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
HH(ref a, b, c, d, x[1], S31, 0xa4beea44); /* 37 */
HH(ref d, a, b, c, x[4], S32, 0x4bdecfa9); /* 38 */
HH(ref c, d, a, b, x[7], S33, 0xf6bb4b60); /* 39 */
HH(ref b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
HH(ref a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
HH(ref d, a, b, c, x[0], S32, 0xeaa127fa); /* 42 */
HH(ref c, d, a, b, x[3], S33, 0xd4ef3085); /* 43 */
HH(ref b, c, d, a, x[6], S34, 0x4881d05); /* 44 */
HH(ref a, b, c, d, x[9], S31, 0xd9d4d039); /* 45 */
HH(ref d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
HH(ref c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
HH(ref b, c, d, a, x[2], S34, 0xc4ac5665); /* 48 */
// Round 4
II(ref a, b, c, d, x[0], S41, 0xf4292244); /* 49 */
II(ref d, a, b, c, x[7], S42, 0x432aff97); /* 50 */
II(ref c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
II(ref b, c, d, a, x[5], S44, 0xfc93a039); /* 52 */
II(ref a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
II(ref d, a, b, c, x[3], S42, 0x8f0ccc92); /* 54 */
II(ref c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
II(ref b, c, d, a, x[1], S44, 0x85845dd1); /* 56 */
II(ref a, b, c, d, x[8], S41, 0x6fa87e4f); /* 57 */
II(ref d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
II(ref c, d, a, b, x[6], S43, 0xa3014314); /* 59 */
II(ref b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
II(ref a, b, c, d, x[4], S41, 0xf7537e82); /* 61 */
II(ref d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
II(ref c, d, a, b, x[2], S43, 0x2ad7d2bb); /* 63 */
II(ref b, c, d, a, x[9], S44, 0xeb86d391); /* 64 */
state[0] += a;
state[1] += b;
state[2] += c;
state[3] += d;
// Zeroize sensitive information.
for (int i = 0; i < x.Length; i++)
x = 0;
}
///
/// Encodes input (uint) into output (byte). Assumes len is
///  multiple of 4.
///
///
///
///
///
///
private static void Encode(byte[] output, int outputOffset, uint[] input, int inputOffset, int count)
{
int i, j;
int end = outputOffset + count;
for (i = inputOffset, j = outputOffset; j < end; i++, j += 4)
{
output[j] = (byte)(input & 0xff);
output[j + 1] = (byte)((input >> 8) & 0xff);
output[j + 2] = (byte)((input >> 16) & 0xff);
output[j + 3] = (byte)((input >> 24) & 0xff);
}
}
///
/// Decodes input (byte) into output (uint). Assumes len is
/// a multiple of 4.
///
///
///
///
///
///
static private void Decode(uint[] output, int outputOffset, byte[] input, int inputOffset, int count)
{
int i, j;
int end = inputOffset + count;
for (i = outputOffset, j = inputOffset; j < end; i++, j += 4)
output = ((uint)input[j]) | (((uint)input[j + 1])