Java动态类加载器(加载外部jar包类 读取资源文件)

Code：

package xx.xx.xx

import java.io.IOException;
import java.io.InputStream;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * 动态类加载器
 * 
 */
public class DynamicJarClassLoader extends ClassLoader {

private static Logger logger = LoggerFactory.getLogger(DynamicJarClassLoader.class);


private JarFile jarFile;


private ClassLoader parent;


public DynamicJarClassLoader(JarFile jarFile) {
super(Thread.currentThread().getContextClassLoader());
this.parent = Thread.currentThread().getContextClassLoader();
this.jarFile = jarFile;
}


public DynamicJarClassLoader(JarFile jarFile, ClassLoader parent) {
super(parent);
this.parent = parent;
this.jarFile = jarFile;
}


@Override
protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
try {
Class c = null;
String path = name.replace('.', '/').concat(".class");
if(null != jarFile){
JarEntry entry = jarFile.getJarEntry(path);
if(null != entry){
InputStream is = jarFile.getInputStream(entry);
int availableLen = is.available();
int len = 0;
byte[] bt1 = new byte[availableLen];
while (len < availableLen) {
len += is.read(bt1, len, availableLen - len);
}
c = defineClass(name, bt1, 0, bt1.length);
if (resolve) {
resolveClass(c);
}
}else{
if (parent != null) {
return parent.loadClass(name);
}
}
}
return c;
} catch (IOException e) {
throw new ClassNotFoundException("Class " + name + " not found.");
}
}


@Override
public InputStream getResourceAsStream(String name) {
InputStream is = null;
try {
if(null != jarFile){
JarEntry entry = jarFile.getJarEntry(name);
if (entry != null) {
is = jarFile.getInputStream(entry);
}
if (is == null) {
is = super.getResourceAsStream(name);
}
}
} catch (IOException e) {
logger.error(e.getMessage());
}
return is;
}
}