Java，使用基于字符串输入的类 [英] Java, use a class based on string input

问题描述

我在Java中制作一个基于命令行的工具，我想我可能能够使我对自己更容易一点，如果我可以采取用户输入，并自动找到所需的功能基于用户输入。

我想做的是，如果用户输入：

用户创建新用户

java代码查找一个名为user的类，然后查找一个名为create的函数，并输入newUser作为函数的第一个参数。意思是键入命令User create newUser将使java代码触发这一行代码：

  User.create ）; 
  

原因，如果没有找到类或函数，返回错误。 >

到目前为止我一直在玩

  Class.forName（cmdArg [ 0]）
  

其中cmdArg [0]是Scanner提供的第一个字，有空格。

无论如何，是否可以在Java中实现这一点？任何帮助将非常感激。

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我的解决方案：

OK，我得到它的工作，我的最终解决方案是duffymo的和user978548的答案的组合，我的解决方案如下：

  class comArgs [] = new Class [1]; 
 comArgs [0] = String.class; 
 
 String [] args = new String [1]; 
 args [0] = commandArray [2]; 
 
 Class.forName（code。+ commandArray [0]）
 .getDeclaredMethod（commandArray [1]，comArgs）
 .invoke（null，args）; 
  

这是被一个try / catch包围的例外，但它可以工作。

我也有一个HashMap用于接收命令。

args variable可以只要被调用方法所需的参数数量。

解决方案

Class.forName（args [0]）。newInstance（）; 为类，和Chin Boon说，你有所有你想要的反射方法。喜欢，运行你的方法：
Object.class.getMethods（）[在这里找到你的方法] .invoke（obj，args）

I'm making a command-line based tool in Java, and I was thinking I might be able to make it all a bit easier on my self if I could take user input and automatically find the needed functions based on the users input.

What I want to do, is, that if a user types:

User create newUser

The java code looks for a class called user, then looks for a function called create, and inputs newUser as the first argument of the function. Meaning typing the command "User create newUser" would make the java code trigger this line of code:

User.create("newUser");

And of cause, return errors if the class or function was not found, or so.

So far I've been playing with

Class.forName(cmdArg[0])

Where cmdArg[0] is the first word given by the Scanner, found by splitting where there's spaces.

Anyway, is it possible to achieve this in Java? Any help would be much appreciated.

---

My solution:

Okay, i got it working, my final solution was a combination of duffymo's and user978548's answer, my solution looks like this:

Class comArgs[] = new Class[1];
comArgs[0] = String.class;

String[] args = new String[1];
args[0] = commandArray[2];

Class.forName("code."+commandArray[0])
    .getDeclaredMethod(commandArray[1], comArgs)
    .invoke(null, args);

This is surrounded by a try/catch with allot of exceptions, but it works.

I also have a HashMap for which commands i want to receive.

The args variable can should be as long as the number of arguments needed for the called method.

解决方案

as duffymo said, Class.forName(args[0]).newInstance(); for the class, and as Chin Boon said, you have all that you want in reflections method. Like, to run your method: Object.class.getMethods()[find your method here].invoke(obj, args)

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