blocks|key|1554689|text|使用getDeclaredMethod()获取私有方法对象，然后使用method.setAccessible()允许实际调用它。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1554690|entityMap^0|2|J|Y|M|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

Use <code>getDeclaredMethod()</code> to get a private Method object and then use <code>method.setAccessible()</code> to allow to actually call it.

blocks|key|1339066|text|您可以使用反射来调用私有方法。修改发布代码的最后一位：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1339067|Method+method+=+object.getClass().getDeclaredMethod(methodName);
method.setAccessible(true);
Object+r+=+method.invoke(object);|code-block|syntax|javascript|1339068|这里有几个警告。首先，getDeclaredMethod将只查找在当前Class中声明的方法，而不是从超类型继承。因此，如果需要的话，遍历具体的类层次结构。其次，SecurityManager可能会阻止使用setAccessible方法。因此，它可能需要(使用AccessController或Subject)作为PrivilegedAction运行。|offset|length|style|CODE|1339069|entityMap^0|0|0|B|H|Z|5|29|F|2V|D|3M|G|43|7|4D|G|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]|$I|V|J|W|K|L]|$I|X|J|Y|K|L]|$I|Z|J|10|K|L]|$I|11|J|12|K|L]|$I|13|J|14|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|N|$]]

You can invoke private method with reflection. Modifying the last bit of the posted code:

<pre><code>Method method = object.getClass().getDeclaredMethod(methodName);
method.setAccessible(true);
Object r = method.invoke(object);
</code></pre>

There are a couple of caveats. First, <code>getDeclaredMethod</code> will only find method declared in the current <code>Class</code>, not inherited from supertypes. So, traverse up the concrete class hierarchy if necessary. Second, a <code>SecurityManager</code> can prevent use of the <code>setAccessible</code> method. So, it may need to run as a <code>PrivilegedAction</code> (using <code>AccessController</code> or <code>Subject</code>).

blocks|key|1339091|text|如果该方法接受非原始数据类型，则可以使用以下方法调用任何类的私有方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1339092|public+static+Object+genericInvokeMethod(Object+obj,+String+methodName,
++++++++++++Object...+params)+{
++++++++int+paramCount+=+params.length;
++++++++Method+method;
++++++++Object+requiredObj+=+null;
++++++++Class<?>[]+classArray+=+new+Class<?>[paramCount];
++++++++for+(int+i+=+0;+i+<+paramCount;+i%2B%2B)+{
++++++++++++classArray[i]+=+params[i].getClass();
++++++++}
++++++++try+{
++++++++++++method+=+obj.getClass().getDeclaredMethod(methodName,+classArray);
++++++++++++method.setAccessible(true);
++++++++++++requiredObj+=+method.invoke(obj,+params);
++++++++}+catch+(NoSuchMethodException+e)+{
++++++++++++e.printStackTrace();
++++++++}+catch+(IllegalArgumentException+e)+{
++++++++++++e.printStackTrace();
++++++++}+catch+(IllegalAccessException+e)+{
++++++++++++e.printStackTrace();
++++++++}+catch+(InvocationTargetException+e)+{
++++++++++++e.printStackTrace();
++++++++}

++++++++return+requiredObj;
++++}|code-block|syntax|javascript|1339093|接受的参数是obj、methodName和参数。例如|1339094|public+class+Test+{
private+String+concatString(String+a,+String+b)+{
++++return+(a%2Bb);
}
}|1339095|方法concatString可以按如下方式调用|1339096|Test+t+=+new+Test();
++++String+str+=+(String)+genericInvokeMethod(t,+"concatString",+"Hello",+"Mr.x");|1339097|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

If the method accepts non-primitive data type then the following method can be used to invoke a private method of any class:

<pre><code>public static Object genericInvokeMethod(Object obj, String methodName,
 Object... params) {
 int paramCount = params.length;
 Method method;
 Object requiredObj = null;
 Class&lt;?&gt;[] classArray = new Class&lt;?&gt;[paramCount];
 for (int i = 0; i &lt; paramCount; i++) {
 classArray[i] = params[i].getClass();
 }
 try {
 method = obj.getClass().getDeclaredMethod(methodName, classArray);
 method.setAccessible(true);
 requiredObj = method.invoke(obj, params);
 } catch (NoSuchMethodException e) {
 e.printStackTrace();
 } catch (IllegalArgumentException e) {
 e.printStackTrace();
 } catch (IllegalAccessException e) {
 e.printStackTrace();
 } catch (InvocationTargetException e) {
 e.printStackTrace();
 }

 return requiredObj;
 }
</code></pre>

The Parameter accepted are obj, methodName and the parameters. For example 

<pre><code>public class Test {
private String concatString(String a, String b) {
 return (a+b);
}
}
</code></pre>

Method concatString can be invoked as 

<pre><code>Test t = new Test();
 String str = (String) genericInvokeMethod(t, "concatString", "Hello", "Mr.x");
</code></pre>

blocks|key|1554752|text|让我通过反射提供执行保护方法的完整代码。它支持任何类型的参数，包括泛型、自动装箱的参数和空值|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1554753|@SuppressWarnings("unchecked")
public+static+<T>+T+executeSuperMethod(Object+instance,+String+methodName,+Object...+params)+throws+Exception+{
++++return+executeMethod(instance.getClass().getSuperclass(),+instance,+methodName,+params);
}

public+static+<T>+T+executeMethod(Object+instance,+String+methodName,+Object...+params)+throws+Exception+{
++++return+executeMethod(instance.getClass(),+instance,+methodName,+params);
}

@SuppressWarnings("unchecked")
public+static+<T>+T+executeMethod(Class+clazz,+Object+instance,+String+methodName,+Object...+params)+throws+Exception+{

++++Method[]+allMethods+=+clazz.getDeclaredMethods();

++++if+(allMethods+!=+null+&&+allMethods.length+>+0)+{

++++++++Class[]+paramClasses+=+Arrays.stream(params).map(p+->+p+!=+null+?+p.getClass()+:+null).toArray(Class[]::new);

++++++++for+(Method+method+:+allMethods)+{
++++++++++++String+currentMethodName+=+method.getName();
++++++++++++if+(!currentMethodName.equals(methodName))+{
++++++++++++++++continue;
++++++++++++}
++++++++++++Type[]+pTypes+=+method.getParameterTypes();
++++++++++++if+(pTypes.length+==+paramClasses.length)+{
++++++++++++++++boolean+goodMethod+=+true;
++++++++++++++++int+i+=+0;
++++++++++++++++for+(Type+pType+:+pTypes)+{
++++++++++++++++++++if+(!ClassUtils.isAssignable(paramClasses[i%2B%2B],+(Class<?>)+pType))+{
++++++++++++++++++++++++goodMethod+=+false;
++++++++++++++++++++++++break;
++++++++++++++++++++}
++++++++++++++++}
++++++++++++++++if+(goodMethod)+{
++++++++++++++++++++method.setAccessible(true);
++++++++++++++++++++return+(T)+method.invoke(instance,+params);
++++++++++++++++}
++++++++++++}
++++++++}

++++++++throw+new+MethodNotFoundException("There+are+no+methods+found+with+name+"+%2B+methodName+%2B+"+and+params+"+%2B
++++++++++++Arrays.toString(paramClasses));
++++}

++++throw+new+MethodNotFoundException("There+are+no+methods+found+with+name+"+%2B+methodName);
}|code-block|syntax|javascript|1554754|方法使用apache+ClassUtils检查自动装箱参数的兼容性。|1554755|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Let me provide complete code for execution protected methods via reflection. It supports any types of params including generics, autoboxed params and null values

<pre><code>@SuppressWarnings("unchecked")
public static &lt;T&gt; T executeSuperMethod(Object instance, String methodName, Object... params) throws Exception {
 return executeMethod(instance.getClass().getSuperclass(), instance, methodName, params);
}

public static &lt;T&gt; T executeMethod(Object instance, String methodName, Object... params) throws Exception {
 return executeMethod(instance.getClass(), instance, methodName, params);
}

@SuppressWarnings("unchecked")
public static &lt;T&gt; T executeMethod(Class clazz, Object instance, String methodName, Object... params) throws Exception {

 Method[] allMethods = clazz.getDeclaredMethods();

 if (allMethods != null &amp;&amp; allMethods.length &gt; 0) {

 Class[] paramClasses = Arrays.stream(params).map(p -&gt; p != null ? p.getClass() : null).toArray(Class[]::new);

 for (Method method : allMethods) {
 String currentMethodName = method.getName();
 if (!currentMethodName.equals(methodName)) {
 continue;
 }
 Type[] pTypes = method.getParameterTypes();
 if (pTypes.length == paramClasses.length) {
 boolean goodMethod = true;
 int i = 0;
 for (Type pType : pTypes) {
 if (!ClassUtils.isAssignable(paramClasses[i++], (Class&lt;?&gt;) pType)) {
 goodMethod = false;
 break;
 }
 }
 if (goodMethod) {
 method.setAccessible(true);
 return (T) method.invoke(instance, params);
 }
 }
 }

 throw new MethodNotFoundException("There are no methods found with name " + methodName + " and params " +
 Arrays.toString(paramClasses));
 }

 throw new MethodNotFoundException("There are no methods found with name " + methodName);
}
</code></pre>

Method uses apache ClassUtils for checking compatibility of autoboxed params

blocks|key|1555639|text|另一个变体是使用功能非常强大的JOOR库https://github.com/jOOQ/jOOR|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1555640|MyObject+myObject+=+new+MyObject()
on(myObject).get("privateField");++|code-block|syntax|javascript|1555641|它允许修改任何字段，如最终静态常量和调用任何受保护的方法，而无需在继承层次结构中指定具体的类|1555642|
<dependency>
+++++<groupId>org.jooq</groupId>
+++++<artifactId>joor-java-8</artifactId>
+++++<version>0.9.7</version>
</dependency>|1555643|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/jOOQ/jOOR^0|K|S|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

One more variant is using very powerfull JOOR library <a href="https://github.com/jOOQ/jOOR" rel="nofollow noreferrer">https://github.com/jOOQ/jOOR</a>

<pre><code>MyObject myObject = new MyObject()
on(myObject).get("privateField"); 
</code></pre>

It allows to modify any fields like final static constants and call yne protected methods without specifying concrete class in the inheritance hierarhy 

<pre><code>&lt;!-- https://mvnrepository.com/artifact/org.jooq/joor-java-8 --&gt;
&lt;dependency&gt;
 &lt;groupId&gt;org.jooq&lt;/groupId&gt;
 &lt;artifactId&gt;joor-java-8&lt;/artifactId&gt;
 &lt;version&gt;0.9.7&lt;/version&gt;
&lt;/dependency&gt;
</code></pre>

blocks|key|1555694|text|您可以使用ReflectionTestUtils+of+Spring+(org.springframework.test.util.ReflectionTestUtils)来实现这一点|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1555695|ReflectionTestUtils.invokeMethod(instantiatedObject,"methodName",argument);|code-block|syntax|javascript|1555696|示例:如果您有一个具有私有方法square(int+x)的类|style|CODE|1555697|Calculator+calculator+=+new+Calculator();
ReflectionTestUtils.invokeMethod(calculator,"square",10);|1555698|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/test/util/ReflectionTestUtils.html^0|10|1D|0|0|0|F|D|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|11|8|@$A|12|B|13|K|L]]|9|@]|C|$]]|$1|M|3|N|5|F|7|14|8|@]|9|@]|C|$G|H]]|$1|O|3|-4|5|6|7|15|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]]]

you can do this using ReflectionTestUtils of Spring (<a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/test/util/ReflectionTestUtils.html" rel="noreferrer">org.springframework.test.util.ReflectionTestUtils</a>)

<pre><code>ReflectionTestUtils.invokeMethod(instantiatedObject,"methodName",argument);
</code></pre>

Example : if you have a class with a private method <code>square(int x)</code>

<pre><code>Calculator calculator = new Calculator();
ReflectionTestUtils.invokeMethod(calculator,"square",10);
</code></pre>

I have a class that uses XML and reflection to return <code>Object</code>s to another class.

Normally these objects are sub fields of an external object, but occasionally it's something I want to generate on the fly. I've tried something like this but to no avail. I believe that's because Java won't allow you to access <code>private</code> methods for reflection.

<pre><code>Element node = outerNode.item(0);
String methodName = node.getAttribute("method");
String objectName = node.getAttribute("object");

if ("SomeObject".equals(objectName))
 object = someObject;
else
 object = this;

method = object.getClass().getMethod(methodName, (Class[]) null);
</code></pre>

If the method provided is <code>private</code>, it fails with a <code>NoSuchMethodException</code>. I could solve it by making the method <code>public</code>, or making another class to derive it from.

Long story short, I was just wondering if there was a way to access a <code>private</code> method via reflection.

Any way to Invoke a private method?

Java

我有一个类，它使用XML和反射将Object返回给另一个类。通常情况下，这些对象是外部对象的子字段，但有时也是我想要动态生成的。我试过这样的方法，但没有用。我相信这是因为Java不允许你访问private方法来进行反射。Element node = outerNode.item(0);String methodName...

问有什么方法可以调用私有方法吗？
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