基于bcel的class动态编译

1:下载源码

http://public.dhe.ibm.com/software/dw/library/j-dyn7.zip

bcel jar

http://download.youkuaiyun.com/detail/qq_16590151/9701906

2:编译代码

项目路径:/opt/test/thread

cd /opt/test/thread

编译java文件

javac /opt/test/thread/src/com/test/wm/StringBuilder.java

运行java文件

java com.test.wm.StringBuilder 100 200 300
Constructed string of length 100
Constructed string of length 200
Constructed string of length 300

bcel动态编译class文件

java -cp /opt/test/bcel.jar:. com.test.wm.BCELTiming /opt/test/thread/src/com/test/wm/StringBuilder.class buildString

运行动态编译后的class文件

java -XX:-UseSplitVerifier com.test.wm.StringBuilder 100 200 300
Call to method buildString$impl took 1 ms.
Constructed string of length 100
Call to method buildString$impl took 0 ms.
Constructed string of length 200
Call to method buildString$impl took 2 ms.
Constructed string of length 300

使用场景

1：cat埋点（企业各应用统一日志输出、可动态编译spring底层调用、jdbc底层查询）

2：统一日志输出

3：上文中的耗时打印