标签：20Files jdk1.8 Java Program% 111 file 加载
ClassLoader的分类
Java中的ClassLoader有三种：Bootstrap ClassLoader 、Extension ClassLoader、App ClassLoader。以下是jdk1.8的类加载器
加载路径
package com.example.demo;
import java.net.URL;
import java.net.URLClassLoader;
public class Test {
public static void main(String[] args) {
System.out.println("BootstrapClassLoader 的加载路径: ");
//String[] bootUrls = System.getProperty("sun.boot.class.path").split(";");
URL[] urls = sun.misc.Launcher.getBootstrapClassPath().getURLs();
for (URL url : urls)
System.out.println(url);
System.out.println("----------------------------");
//取得扩展类加载器
URLClassLoader extClassLoader = (URLClassLoader) ClassLoader.getSystemClassLoader().getParent();
System.out.println(extClassLoader);
System.out.println("扩展类加载器 的加载路径: ");
urls = extClassLoader.getURLs();
for (URL url : urls)
System.out.println(url);
System.out.println("----------------------------");
//取得应用(系统)类加载器
URLClassLoader appClassLoader = (URLClassLoader) ClassLoader.getSystemClassLoader();
System.out.println(appClassLoader);
System.out.println("应用(系统)类加载器 的加载路径: ");
urls = appClassLoader.getURLs();
for (URL url : urls)
System.out.println(url);
System.out.println("----------------------------");
}
}
运行结果如下：
BootstrapClassLoader 的加载路径:
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/resources.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/rt.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/sunrsasign.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/jsse.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/jce.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/charsets.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/jfr.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/classes
----------------------------
sun.misc.Launcher$ExtClassLoader@776ec8df
扩展类加载器 的加载路径:
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/access-bridge-64.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/cldrdata.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/dnsns.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/jaccess.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/jfxrt.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/localedata.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/nashorn.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/sunec.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/sunjce_provider.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/sunmscapi.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/sunpkcs11.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/zipfs.jar
----------------------------
sun.misc.Launcher$AppClassLoader@18b4aac2
应用(系统)类加载器 的加载路径:
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/charsets.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/deploy.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/access-bridge-64.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/cldrdata.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/dnsns.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/jaccess.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/jfxrt.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/localedata.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/nashorn.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/sunec.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/sunjce_provider.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/sunmscapi.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/sunpkcs11.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/ext/zipfs.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/javaws.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/jce.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/jfr.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/jfxswt.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/jsse.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/management-agent.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/plugin.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/resources.jar
file:/F:/Program%20Files/Java/jdk1.8.0_111/jre/lib/rt.jar
file:/F:/myproject/demo/target/classes/
自定义类加载器
package com.example.demo;
public class Test {
public static void main(String[] args) throws ClassNotFoundException {
String classPath = "F:/";
CustomerClassLoader myClassLoader = new CustomerClassLoader(classPath);
String packageNamePath = "LogTest";
Class logTest = myClassLoader.loadClass(packageNamePath);
System.out.println("classloader is :" + logTest.getClassLoader().getClass().getName());
}
}
package com.example.demo;
import java.io.FileInputStream;
public class CustomerClassLoader extends ClassLoader {
private String loadPath;
public CustomerClassLoader(String loadPath) {
this.loadPath = loadPath;
}
@Override
protected Class<?> findClass(String name) throws ClassNotFoundException {
try {
byte[] bytes = loadByte(name);
return defineClass(name, bytes, 0, bytes.length);
} catch (Exception e) {
System.out.println(e.getMessage());
}
return null;
}
private byte[] loadByte(String className) throws Exception {
className = className.replaceAll("\\.", "/");
FileInputStream fileInputStream = new FileInputStream(loadPath + "/" + className + ".class");
int available = fileInputStream.available();
byte[] data = new byte[available];
fileInputStream.read(data);
fileInputStream.close();
return data;
}
}
标签：20Files,jdk1.8,Java,Program%,111,file,加载 来源： https://blog.csdn.net/duqingqing5666/article/details/121396449
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