/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package cn.com.bricks.dynamic.weaving;
import cn.com.bricks.dynamic.loader.util.DynamicDeployUtil;
import cn.com.bricks.dynamic.weaving.utils.WeavingConfigUtil;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.security.ProtectionDomain;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
/**
*
* @author kete
*/
public class UnitTestTransformer implements ClassFileTransformer {
private Log log = LogFactory.getLog(UnitTestTransformer.class);
public static void premain(String agentArgs, Instrumentation inst) {
System.out.println("javaagent start");
inst.addTransformer(new UnitTestTransformer());
}
@Override
public byte[] transform(ClassLoader loader, String className,
Class<?> classBeingRedefined, ProtectionDomain protectionDomain,
byte[] classfileBuffer) throws IllegalClassFormatException {
byte[] result = classfileBuffer; //定义新的字节码存储变量
if (log.isTraceEnabled()) {
log.trace("Loading " + className + " by " + loader.toString());
}
// 判断是否重新加载类文件，并实现动态部署
if (DynamicDeployUtil.isReloadResource(className)) {
if (log.isTraceEnabled()) {
log.trace("Reloading " + className + " by " + loader.toString());
}
result = DynamicDeployUtil.findResource(className);
}
//在此通过修改类的字节码 classfileBuffer，来更改类。
if (!WeavingConfigUtil.INSTANCE.isWeavingLoader(loader)) {
return result;
}
boolean isWeavingClass = true;
// 此处判断不需要修改的类将不进行修改
if (WeavingConfigUtil.INSTANCE.isNoWeavingClassAndPkgs(className)) {
isWeavingClass = false;
}
boolean isWeavingPkgs = false;
// 处理包的weaving
String jarName = (protectionDomain != null && protectionDomain.getCodeSource() != null && protectionDomain.getCodeSource().getLocation() != null) ? protectionDomain.getCodeSource().getLocation().getFile() : "";
// 如果当前路径为classes下或为自定义的classloader(protectionDomain为NULL)需要weaving
if ((isWeavingClass && WeavingConfigUtil.INSTANCE.isWeavingJar(jarName)) || protectionDomain == null) {
isWeavingPkgs = true;
}
// weaving处理
if (isWeavingClass && isWeavingPkgs || WeavingConfigUtil.INSTANCE.isReplaceClass(className)) {
if (log.isTraceEnabled()) {
log.trace("Weaving " + className + " by ASM4.1");
}
ClassReader reader = new ClassReader(result);
ClassWriter writer = new ClassWriter(WeavingConfigUtil.INSTANCE.isDebug() ? ClassWriter.COMPUTE_FRAMES : ClassWriter.COMPUTE_MAXS);
ClassVisitor adapter = new UnitClassWeavingAdapter(writer, className);
reader.accept(adapter, WeavingConfigUtil.INSTANCE.isDebug() ? ClassReader.SKIP_FRAMES : ClassReader.SKIP_DEBUG);
result = writer.toByteArray();
}
return result; //返回新的字节码
}
}