2

我想弄清楚如何使用反射。我已经设置了 2 个类，其中一个对数字进行了基本验证

public class Reflectee {

    String str;

    public Reflectee(String str){
        this.str=str;
    }

    public Reflectee(){

    }
    public boolean doSomething(String str){
        boolean flag=true;
        try{
            Integer.parseInt(str);
        }catch (NumberFormatException e){
            flag=false;
        }
        return flag;
    }
}

然后我创建了一个将使用反射来调用 doSomething 方法的类。

public class Reflector {

    private String str="22";

    public boolean reflect(){
        Reflectee r=new Reflectee();
        Class clazz=r.getClass();
        boolean b=false;
        try {
            Method m=clazz.getDeclaredMethod("doSomething",String.class);
            b=(Boolean)m.invoke(this,str); //Exception is here
        } catch (NoSuchMethodException | SecurityException |
                IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return b;
    }
}

当我尝试调用异常的方法时出现异常

java.lang.IllegalArgumentException: object is not an instance of declaring class
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.app.example2.Reflector.reflect(Reflector.java:16)
    at com.app.example2.test.Reflector_UT.test(Reflector_UT.java:16)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

我确信我错过了一些小事。有什么想法有什么问题吗？

谢谢

4

1 回答 1

6

问题在以下行

 b=(Boolean)m.invoke(this,str); //Exception is here

您必须在 Reflectee 对象上调用方法而不是 this(Reflector object)

 b=(Boolean)m.invoke(r,str); //Exception is here
于 2013-10-17T01:10:04.237 回答