//file-name:FtmAgent.java
package com.zyh.ftmagent;

import java.lang.instrument.Instrumentation;
import java.lang.instrument.UnmodifiableClassException;

public class FtmAgent {
    public static void premain(String agentArgs, Instrumentation inst)
            throws ClassNotFoundException, UnmodifiableClassException{
            inst.addTransformer(new TimeTransformer());
        }
}

//file-name:TimeTransformer.java
package com.zyh.ftmagent;

import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;

import javassist.CannotCompileException;
import javassist.ClassPool;
import javassist.CtBehavior;
import javassist.CtClass;
import javassist.NotFoundException;
import javassist.expr.ExprEditor;
import javassist.expr.MethodCall;
import javassist.expr.NewExpr;

public class TimeTransformer implements ClassFileTransformer {

    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
            ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
        // 仅对于com.zyh.test包下的类进行替换
        if (className.startsWith("com/zyh/test")) {
            byte[] transformed = null;
            System.out.println("Transforming " + className);
            ClassPool pool = ClassPool.getDefault();
            CtClass cl = null;
            try {
                cl = pool.makeClass(new java.io.ByteArrayInputStream(classfileBuffer));
                if (cl.isInterface() == false) {
                    CtBehavior[] methods = cl.getDeclaredBehaviors();
                    for (int i = 0; i < methods.length; i++) {
                        if (methods[i].isEmpty() == false) {
                            doMethod(methods[i]);
                        }
                    }
                    transformed = cl.toBytecode();
                }
            } catch (Exception e) {
                System.err.println("Could not instrument    " + className + ",    exception : " + e.getMessage());
            } finally {
                if (cl != null) {
                    cl.detach();
                }
            }
            return transformed;
        }
        return null;
    }

    private void doMethod(CtBehavior method) throws NotFoundException, CannotCompileException {
        // 修改方法体的定义
        method.instrument(new ExprEditor() {

            // 修改一般的方法调用语句
            public void edit(MethodCall m) throws CannotCompileException {
                try {
                    if (m.getClassName().equals("java.lang.System")) {
                        if (m.getMethodName().equals("nanoTime")) {
                            m.replace("{long rslt = com.zyh.ftmagent.MySystemTime#nanoTime(); $_ = ($r)rslt; }");
                        } else if (m.getMethodName().equals("currentTimeMillis")) {
                            m.replace(
                                    "{long rslt = com.zyh.ftmagent.MySystemTime#currentTimeMillis(); $_ = ($r)rslt; }");
                        }
                    }
                } catch (Exception ex) {
                    ex.printStackTrace();
                    throw new RuntimeException(ex);
                }
            }

            // 修改new Date()这种格式的代码，替换其中的class类
            public void edit(NewExpr e) throws CannotCompileException {
                try {
                    if (e.getClassName().equals("java.util.Date")) {
                        e.replace("{$_ = new com.zyh.ftmagent.MyDate();}");
                    }
                } catch (Exception ex) {
                    ex.printStackTrace();
                    throw new RuntimeException(ex);
                }
            }
        });
    }
}

//file-name: MyDate.java
package com.zyh.ftmagent;

import java.util.Date;

public class MyDate extends Date {
    private static final long serialVersionUID = 1L;

    public MyDate(){
        super(MySystemTime.currentTimeMillis());
    }
}

//file-name:MySystemTime.java
package com.zyh.ftmagent;

public class MySystemTime {
    //默认为当前时间
    private static final Long INIT_VALUE = 0l;

    private static ThreadLocal<Long> timeDiff = new ThreadLocal<Long>() {
        @Override
        protected Long initialValue() {
            return INIT_VALUE;
        }
    };

    public static long currentTimeMillis() {
        return System.currentTimeMillis() - timeDiff.get();
    }

    public static long nanoTime() {
        return System.nanoTime() - timeDiff.get() * 1000;
    }

    /**
     * 设置距离当前的时间，为正表示后退多少ms
     * 
     * @param diff
     */
    public static void setTimeDiff(long diff) {
        timeDiff.set(diff);
    }
}

Manifest-Version: 1.0
Premain-Class: com.zyh.ftmagent.FtmAgent
Boot-Class-Path: javassist-3.22.0-CR1.jar

Enquire agreementInfo and other info; (no transaction)
Start transaction #spring逻辑
	Get session  #ibatis处理逻辑
		Get Request #ibatis处理逻辑
			Do update account limit
		Return Request #ibatis处理逻辑
	Return session #ibatis处理逻辑
	Sleep 1s #增加的代码，为了便于看出效果
	Get session #ibatis处理逻辑；在这里可能出现拿不到session而阻塞，但这时其实线程是有数据库连接的，因为transaction未断开，不应该出现阻塞
	    Get Request #ibatis处理逻辑
			Insert account transaction information  #预计账务流水
		Return Request #ibatis处理逻辑
	Return session #ibatis处理逻辑
End Transaction #spring逻辑

    <!-- application.xml -->
    <context:component-scan base-package="com.itechlib.com.service" />
    
    <!-- 在测试目录下定义stub类 -->
    <bean id="userDao" class="com.itechlib.com.test.stub.UserDaoStubServiceImpl" />

@component("userService")
class UserServiceImpl implements IUserService {

@Resource(name="userDao")
private IUserDao userDao;

  public void doUpdate(){
    //...
    userDao.update();
    //...
  }
}

@ContextConfiguration(loader = SpringBeanTestContextLoader.class, locations = {
    "classpath:test-resources/application/application.xml"})
class UserServiceTests extends AbstractJunit4SpringContextTests{
    @Test
    public void testUpdate(){
    //...    
    }
}

@ContextConfiguration(loader = SpringBeanTestContextLoader.class, locations = {
    "classpath:test-resources/application/application-custom.xml"})
class OrderServiceTests extends AbstractJunit4SpringContextTests{
    @Test
    public void testAdd(){
    //...    
    }
}