版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/Michaeles/article/details/86666775
1.test
package com.interview.javabasic.reflect;
public class ClassLoaderChecker {
public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException, InstantiationException {
MyClassLoader m = new MyClassLoader("/Users/baidu/Desktop/", "myClassLoader");
Class c = m.loadClass("Wali");
System.out.println(c.getClassLoader());
System.out.println(c.getClassLoader().getParent());
System.out.println(c.getClassLoader().getParent().getParent());
System.out.println(c.getClassLoader().getParent().getParent().getParent());
c.newInstance();
}
}
//wali
public class Wali{
static{
System.out.println("hello");
}
}
2.自定义ClassLoader MyClassLoader.java
package com.interview.javabasic.reflect;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
public class MyClassLoader extends ClassLoader {
private String path;
private String classLoaderName;
public MyClassLoader(String path, String classLoaderName) {
this.path = path;
this.classLoaderName = classLoaderName;
}
//用于寻找类文件
@Override
public Class findClass(String name) {
byte[] b = loadClassData(name);
return defineClass(name, b, 0, b.length);
}
//用于加载类文件
private byte[] loadClassData(String name) {
name = path + name + ".class";
InputStream in = null;
ByteArrayOutputStream out = null;
try {
in = new FileInputStream(new File(name));
out = new ByteArrayOutputStream();
int i = 0;
while ((i = in.read()) != -1) {
out.write(i);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
out.close();
in.close();
} catch (Exception e) {
e.printStackTrace();
}
}
return out.toByteArray();
}
}