Configuration操作web.config

[网字]

有如下代码：

    public class WebConfigRW:IDisposable
    {

        private Configuration config;
        public WebConfigRW() : this(HttpContext.Current.Request.ApplicationPath) { }
        public WebConfigRW(string path) {
            config = WebConfigurationManager.OpenWebConfiguration(path);
        }
        public string ReadConnection(string strName) {
            ConnectionStringsSection conStrSection = (ConnectionStringsSection)config.GetSection("connectionStrings");
            if (conStrSection.ConnectionStrings[strName] == null) {
                return "无 " + strName + " 项";
            }
            else {
                return conStrSection.ConnectionStrings[strName].ConnectionString;
            }
        }
   }

在这一行中

public WebConfigRW() : this(HttpContext.Current.Request.ApplicationPath) { }

，构造函数名后面的冒号及冒后面后的代码，似乎是起到了定位web.config位置的作用，我把其删掉后，ReadConnection(string strName)就提示“未将对象引用设置到对象的实例”。
这种构造函数名后面带冒的用法，还是头一次碰到，我能否在冒号后面自定义自己的路径？它的工作原理是怎么样的？

[tcmakebest]

楼主基础不行啊, 冒号后跟 this 等于是调用另外的构造函数, 多个构造函数共用代码.

[江南小鱼]

public class WebConfigRW:IDisposable
    {

        private Configuration config;
        /*默认构造函数，当实例化WebConfigRW类的时候，如果调用默认构造函数，那么config变量的值就是HttpContext.Current.Request.ApplicationPath*/
        public WebConfigRW() : this(HttpContext.Current.Request.ApplicationPath) { }
        //构造函数
        public WebConfigRW(string path) {
            config = WebConfigurationManager.OpenWebConfiguration(path);
        }
        public string ReadConnection(string strName) {
            ConnectionStringsSection conStrSection = (ConnectionStringsSection)config.GetSection("connectionStrings");
            if (conStrSection.ConnectionStrings[strName] == null) {
                return "无 " + strName + " 项";
            }
            else {
                return conStrSection.ConnectionStrings[strName].ConnectionString;
            }
        }
   }

[江南小鱼]

度娘找找构造函数重载，看看资料，就明白怎么回事了~