我有东西给你。我不知道如何在这里上传 jar 文件,所以只是在这里添加文件。
方法:ClassGenerator 类在 while 循环中创建一个新的类加载器,并一遍又一遍地加载同一个类,直到用完 permgen。现在您会注意到有一个列表保存了已加载类的引用。这是为了防止 JVM 卸载这些类:)。
文件解释
第一张图显示,当您运行该程序时,它耗尽了永久代空间。如果您想在 Eclipse 中进行设置,第二张图显示了项目的结构。我在 eclipse 中测试了它,并将其导出为可运行的 jar 文件,它在两种情况下都有效。
Run as a runnable jar file and it ran out of permgen.
Eclipse 项目设置
类生成器类
package com.vkg;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
public class ClassGenerator {
private static final int BUFFER = 1024;
private List<Class<?>> classList = new ArrayList<Class<?>>();
public static void main(String[] args) {
ClassGenerator classGenerator = new ClassGenerator();
// Load just some class with class loaders until perm gen space fills.
while (true) {
classGenerator.classLoader();
}
}
private void classLoader() {
ClassLoader classLoader = new ClassLoader() {
public Class<?> loadClass(String classNameWithPackage)
throws ClassNotFoundException {
if (!classNameWithPackage.contains("DummyClass")) {
return super.loadClass(classNameWithPackage);
}
String className = classNameWithPackage.replace('.', '/')
+ ".class";
byte[] classData = null;
InputStream inputStream = null;
try {
inputStream = getResourceAsStream(className);
byte[] buffer = new byte[BUFFER];
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
int bytesRead = -1;
while ((bytesRead = inputStream.read(buffer, 0, BUFFER)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
classData = outputStream.toByteArray();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (inputStream != null) {
try {
inputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
Class<?> c = defineClass(classNameWithPackage, classData, 0,
classData.length);
resolveClass(c);
System.out
.println("Steve I am loading another copy of Dummy class. Soon Permgen will fill.");
classList.add(c);
return c;
}
};
try {
Class.forName("com.vkg.DummyClass", true, classLoader);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
虚拟类。这可以是任何类。该类的唯一目的是多次加载。没有其他用途。此类中不执行任何逻辑。主要逻辑在ClassGenerator.java中
package com.vkg;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
public class DummyClass {
public void classLoader() {
ClassLoader classLoader = new ClassLoader() {
public Class<?> loadClass(String classNameWithPackage) throws ClassNotFoundException {
if(!classNameWithPackage.contains("DummyClass")) {
return super.loadClass(classNameWithPackage);
}
String className = classNameWithPackage.replace('.', '/') + ".class";
byte[] classData = null;
try {
InputStream inputStream = getResourceAsStream(className);
byte[] buffer = new byte[1];
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
int bytesRead = -1;
while ((bytesRead = inputStream.read(buffer, 0, 1)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
classData = outputStream.toByteArray();
}
catch (IOException e) {
e.printStackTrace();
}
Class<?> c = defineClass(classNameWithPackage, classData, 0, classData.length);
resolveClass(c);
System.out.println("Steve I am loading another copy of Dummy class. Soon Permgen will fill.");
return c;
}
};
try {
Class.forName("com.vkg.DummyClass", true, classLoader);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
希望它可以帮助您测试服务器崩溃。