C#特性学习笔记二

实例探讨:

自定义了一个特性类：

 

[AttributeUsage(AttributeTargets.Class|AttributeTargets.Method)]
class WahAttribute:System.Attribute
{
    private string description;

    public string Description
    {
        get { return description; }
        set { description = value; }
    }
    private string author;

    public string Author
    {
        get { return author; }
        set { author = value; }
    }
    public WahAttribute(string desc)
    {
        this.description = desc;
    }
}

[AttributeUsage(AttributeTargets.Class|AttributeTargets.Method)] class WahAttribute:System.Attribute { private string description; public string Description { get { return description; } set { description = value; } } private string author; public string Author { get { return author; } set { author = value; } } public WahAttribute(string desc) { this.description = desc; } }

 

运用特性类：

 

namespace attributeDemo
{
    public class Teacher
    {
        private string name;

        public string Name
        {
            get { return name; }
            set { name = value; }
        }
        private int age;

        public int Age
        {
            get { return age; }
            set { age = value; }
        }
        private string sex;

        public string Sex
        {
            get { return sex; }
            set { sex = value; }
        }
        //只有用户名为wah的才可以调用此方法
        [Wah("this is my attribute test", Author = "wah", Description = "test")]
        public string getMessage()
        {
            return "好好学习，天天向上";
        }
        [Wah("this is with parameters test",Author="wanggaihui",Description="test with parameters")]
        public int Test(int a,int b)
        {
            return a+b;
        }
    }
}

namespace attributeDemo { public class Teacher { private string name; public string Name { get { return name; } set { name = value; } } private int age; public int Age { get { return age; } set { age = value; } } private string sex; public string Sex { get { return sex; } set { sex = value; } } //只有用户名为wah的才可以调用此方法 [Wah("this is my attribute test", Author = "wah", Description = "test")] public string getMessage() { return "好好学习，天天向上"; } [Wah("this is with parameters test",Author="wanggaihui",Description="test with parameters")] public int Test(int a,int b) { return a+b; } } }

 

处理特性类：

 

private void button_Click(object sender, EventArgs e)
{
    //得到类型
    Type type = typeof(Teacher);
    //得到此类型所有方法
    MethodInfo[] methods = type.GetMethods();
    foreach (MethodInfo method in methods)
    {
        //得到此方法的所有特性
        object[] attributes = method.GetCustomAttributes(false);
        foreach (object o in attributes)
        {
            //判断是否是自己定义的特性
            if (o.GetType() == typeof(WahAttribute))
            {
                //强转取得值
                WahAttribute waha = (WahAttribute)o;
                this.listBox1.Items.Add("author=" + waha.Author);
                this.listBox1.Items.Add("description=" + waha.Description);
            }
        }
    }
}

private void button_Click(object sender, EventArgs e) { //得到类型 Type type = typeof(Teacher); //得到此类型所有方法 MethodInfo[] methods = type.GetMethods(); foreach (MethodInfo method in methods) { //得到此方法的所有特性 object[] attributes = method.GetCustomAttributes(false); foreach (object o in attributes) { //判断是否是自己定义的特性 if (o.GetType() == typeof(WahAttribute)) { //强转取得值 WahAttribute waha = (WahAttribute)o; this.listBox1.Items.Add("author=" + waha.Author); this.listBox1.Items.Add("description=" + waha.Description); } } } }

 

C#特性可以应用于各种类型和成员。加在类前面的是类特性，加在方法前面的是方法特性。无论他们被用在哪里，无论他们之间有什么区别，特性的最主要的目的就是自描述。并且因为特性是可以由自己定制的，而不仅仅局限于.net提供的那几个现成的，因此给C#程序开发带来了很大的灵活性。