importjava.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.lang.reflect.Method;
public class AutoClassLoader extends ClassLoader {
//定义文件所在目录
privatestatic final String DEAFAULTDIR= "d://testclass//";
//定义文件绝对路径
privatestatic String FILEPATH="";
publicClass<?> findClass(String name)throws ClassNotFoundException {
byte[] b =null;
try {
b =loadClassData(AutoClassLoader.FormatClassName(name));
} catch(Exception e) {
e.printStackTrace();
}
//调用了DefineClass方法，目的在于把从文件中得到的二进制 数组转换为相应的Class实例。
//DefineClass是一个Native的方法，它替我们识别Class文件格式，分析、读取相应的数据结构，并生成一个Class实例。
return defineClass(name, b, 0, b.length);
}
privatebyte[] loadClassData(String filepath) throws Exception {
int n=0;
BufferedInputStream br = new BufferedInputStream(
newFileInputStream(
newFile(filepath)));
ByteArrayOutputStream bos= new ByteArrayOutputStream();
while((n=br.read())!=-1){
bos.write(n);
}
br.close();
returnbos.toByteArray();
}
publicstatic String FormatClassName(String name){
FILEPATH=DEAFAULTDIR + name+".class";
returnFILEPATH;
}
publicstatic void main(String[] args) throws Exception {
AutoClassLoader acl = new AutoClassLoader();
Class c =acl.findClass("TestClass");
Object obj =c.newInstance();
Method m =c.getMethod("getName",new Class[]{String.class ,int.class});
m.invoke(obj,"你好",123);
System.out.println(c.getName());
System.out.println(c.getClassLoader());
System.out.println(c.getClassLoader().getParent());
}
}
打印结果：
hello ~!你好@@123
TestClass
AutoClassLoader@757aef
sun.misc.Launcher$AppClassLoader@82ba41
============================================================================
public class TestClass {
public voidgetName(String param,int i) {