同事问到C#中的属性(Property)怎么理解?
同事问到C#中的属性(Property)怎么理解?我说“属性就是对私有字段进行读取。”事后分析,其实属性还是值得研究的,首先属性是类、结构、接口的命名成员,它提供了通过访问器读、写或者计算私有字段值的灵活机制。举个例子:通过User类来记录用户注册信息。
注意:属性(Property)的调用跟类的字段的调用方法一样,赋值用等号。读取跟类的字段的读取方法一样。值得注意的是:private string name; public string Name;这样在C#中没有问题,但是如果在一个工程文件中存在多种语言,比如VB.NET.那么就会出现问题,个人建议把字段名称前面加一个标志符,比如:u_name、U_sex.这样就方便很多。
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using System;
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class User
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{
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public string name;
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public string sex;
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}
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class Property
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{
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static void Main()
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{
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User zm=new User();
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zm.name="无为";
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zm.sex="天";
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Console.WriteLine("姓名:"+zm.name+"性别:"+zm.sex);
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}
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}
17![](/Images/OutliningIndicators/None.gif)
此时如果用户输入的性别为其他的,比如“猪”,哈哈,是不是一样可以通过编译器了?解决方法是:
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using System;
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class User
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{
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public string name;
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public string sex;
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public void SetSex(string values)
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{
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if (values=="男"||values=="女")
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{
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sex=values;
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}
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else
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{
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Console.WriteLine("性别只能是男或者女");
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}
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}
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}
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class Property
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{
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static void Main()
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{
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User zm=new User();
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zm.name="无为";
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zm.SetSex("天");
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Console.WriteLine("姓名:"+zm.name+"性别:"+zm.sex);
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}
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}
28![](/Images/OutliningIndicators/None.gif)
问题解决:但是值得注意的是name、sex还是public属性,依然可以修改,给name、sex设置为public,破坏了类的封装,存在潜在的危险。应该设置为private.这样就需要用到属性的知识去声明,读取这两个字段。代码如下:
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using System;
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class User
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{
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private string name;
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private string sex;
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public void SetName(string values)
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{
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name=values;
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}
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public string GetName()
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{
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return name;
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}
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public void SetSex(string values)
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{
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if (values=="男"||values=="女")
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{
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sex=values;
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}
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else
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{
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Console.WriteLine("性别只能为“男”或者“女”");
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}
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}
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public string GetSex()
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{
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return sex;
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}
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public string Name
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{
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get
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{
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return name;
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}
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set
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{
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name=value;//隐含参数
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}
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}
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public string Sex
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{
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get
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{
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return sex;
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}
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set
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{
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if (value=="男"||value=="女")
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{
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sex=value;
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}
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else
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{
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Console.WriteLine("性别只能为“男”或者“女”");
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}
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}
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}
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}
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class Property
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{
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static void Main()
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{
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User zm=new User();
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zm.SetName("无为");
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zm.SetSex("男");
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Console.WriteLine("姓名:"+zm.GetName()+" 性别:"+zm.GetSex()); //方法调用
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zm.Name="WuWei"; //属性调用
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zm.Sex="天";
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Console.WriteLine("姓名:"+zm.Name+" 性别:"+zm.Sex);
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}
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}
72![](/Images/OutliningIndicators/None.gif)
从运行结果上看,把“无为”改成了“WuWei”,并且zm.Sex="天"没有对性别做修改。 ![](/Images/OutliningIndicators/None.gif)
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注意:属性(Property)的调用跟类的字段的调用方法一样,赋值用等号。读取跟类的字段的读取方法一样。值得注意的是:private string name; public string Name;这样在C#中没有问题,但是如果在一个工程文件中存在多种语言,比如VB.NET.那么就会出现问题,个人建议把字段名称前面加一个标志符,比如:u_name、U_sex.这样就方便很多。