How to use reflection and dynamically load assemblies in C#

How to use reflection and dynamically load assemblies in C

#Introduction:
In C#, reflection (Reflection) is a powerful mechanism that allows We obtain and operate the program's metadata at runtime, including type information, member information, etc. Dynamically loading assemblies is a common application implemented through reflection, and is very useful in some specific scenarios. This article will introduce in detail how to use reflection and dynamically load assemblies in C#, and provide specific code examples.

1. The basic concept of reflection
   Reflection is an important feature in the C# language, which allows the program to dynamically obtain and manipulate type information at runtime. Reflection can help us implement some advanced functions, such as dynamically loading assemblies, creating objects, calling methods, etc. In C#, the reflection mechanism is supported through the System.Reflection namespace.
2. Dynamic loading of assembly
   Dynamic loading of assembly means loading and using the assembly through code when the program is running, rather than statically referencing it at compile time. The advantage of this is that assemblies can be dynamically loaded and unloaded as needed, improving the flexibility of the application.

The following will demonstrate how to dynamically load an assembly in C#:

Step 1: Create a class library project
First, we create a class library project for Dynamically load and use assemblies. Add a class named "DynamicAssembly" to the project and implement a simple method for printing a message on the console. The code is as follows:

using System;

namespace DynamicAssembly
{
    public class DynamicClass
    {
        public void PrintMessage()
        {
            Console.WriteLine("Hello, Dynamic Assembly!");
        }
    }
}

In this project, we will generate An assembly file named "DynamicAssembly.dll". This file will contain the DynamicClass class and its methods.

Step 2: Create a console application
Next, we create a console application project to dynamically load and use the assembly created previously. Add a class named "DynamicLoading" to the project and implement the following code:

using System;
using System.Reflection;

namespace DynamicLoading
{
    class Program
    {
        static void Main(string[] args)
        {
            // 加载程序集
            Assembly assembly = Assembly.LoadFile("绝对路径\DynamicAssembly.dll");

            // 获取类型
            Type type = assembly.GetType("DynamicAssembly.DynamicClass");

            // 创建对象
            object obj = Activator.CreateInstance(type);

            // 调用方法
            MethodInfo method = type.GetMethod("PrintMessage");
            method.Invoke(obj, null);
        }
    }
}

The "absolute path" in the above code needs to be modified to the absolute path where "DynamicAssembly.dll" is located.

In this program, we first use the Assembly.LoadFile method to load the "DynamicAssembly.dll" assembly. Then, get the DynamicClass type through the Assembly.GetType method. Next, use the Activator.CreateInstance method to create an instance of DynamicClass. Finally, use the MethodInfo.Invoke method to call the PrintMessage method of DynamicClass.

Run the console application and you will see the "Hello, Dynamic Assembly!" message output on the console.

Conclusion:
Reflection and dynamic loading of assemblies are important and powerful features in C#. The reflection mechanism allows us to obtain and manipulate program metadata at runtime. Dynamically loading assemblies allows us to load and use assemblies at runtime as needed, improving the flexibility of the application. With the sample code in this article, you can better understand how to use reflection and dynamically load assemblies in C#.

Through reflection and dynamic loading of assemblies, we can achieve more flexible and scalable applications. In practical applications, dynamically loaded assemblies are often used in plug-in or modular development to dynamically expand the functionality of applications. At the same time, the reflection mechanism also provides basic support for some other advanced functions in the C# language, such as generics, LINQ, etc. Therefore, it is very beneficial for C# developers to master the use of reflection and dynamically loaded assemblies.

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