InvocationTargetException异常解析

InvocationTargetException异常由Method.invoke(obj, args...)方法抛出。当被调用的方法的内部抛出了异常而没有被捕获时，将由此异常接收。

示例：

 package com.zzj.test.reflect;

 public class Reflect {
     public void run(int i) throws ZeroException {
         B b = new B();
         b.run(i);
     }
 }

 class B {
     public void run(int i) throws ZeroException {
         if (i < 0) {
             throw new ZeroException("参数不能小于零！");
         }
         System.out.println("参数：" + i);

     }
 }

 class ZeroException extends Exception {
     private static final long serialVersionUID = 1L;

     private String detailMessage;

     public ZeroException(String detailMessage) {
         this.detailMessage = detailMessage;
     }

     public String getMessage() {
         return detailMessage;
     }
 }

测试：

 package com.zzj.test.reflect;

 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;

 public class Test {
     public static void main(String[] args) {
         try {
             Class<?> clazz = Class.forName("com.zzj.test.reflect.Reflect");
             Method method = clazz.getMethod("run", int.class);
             method.invoke(clazz.newInstance(), -1);
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         } catch (SecurityException e) {
             e.printStackTrace();
         } catch (NoSuchMethodException e) {
             e.printStackTrace();
         } catch (IllegalArgumentException e) {
             e.printStackTrace();
         } catch (IllegalAccessException e) {
             e.printStackTrace();
         } catch (InvocationTargetException e) {
             System.out.println("此处接收被调用方法内部未被捕获的异常");
             e.printStackTrace();
         } catch (InstantiationException e) {
             e.printStackTrace();
         }
     }
 }

输出：

 此处接收被调用方法内部未被捕获的异常
 java.lang.reflect.InvocationTargetException
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
     at java.lang.reflect.Method.invoke(Unknown Source)
     at com.zzj.test.reflect.Test.main(Test.java:11)
 Caused by: com.zzj.test.reflect.ZeroException: 参数不能小于零！
     at com.zzj.test.reflect.B.run(Reflect.java:13)
     at com.zzj.test.reflect.Reflect.run(Reflect.java:6)
     ... 5 more

也可以直接打印目标异常：

 package com.zzj.test.reflect;

 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;

 public class Test {
     public static void main(String[] args) {
         try {
             Class<?> clazz = Class.forName("com.zzj.test.reflect.Reflect");
             Method method = clazz.getMethod("run", int.class);
             method.invoke(clazz.newInstance(), -1);
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         } catch (SecurityException e) {
             e.printStackTrace();
         } catch (NoSuchMethodException e) {
             e.printStackTrace();
         } catch (IllegalArgumentException e) {
             e.printStackTrace();
         } catch (IllegalAccessException e) {
             e.printStackTrace();
         } catch (InvocationTargetException e) {
             System.out.println("此处接收被调用方法内部未被捕获的异常");
             Throwable t = e.getTargetException();// 获取目标异常
             t.printStackTrace();
         } catch (InstantiationException e) {
             e.printStackTrace();
         }
     }
 }

输出：

 此处接收被调用方法内部未被捕获的异常
 com.zzj.test.reflect.ZeroException: 参数不能小于零！
     at com.zzj.test.reflect.B.run(Reflect.java:13)
     at com.zzj.test.reflect.Reflect.run(Reflect.java:6)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
     at java.lang.reflect.Method.invoke(Unknown Source)
     at com.zzj.test.reflect.Test.main(Test.java:11)