javaassist used in the hibernate

最新推荐文章于 2022-11-25 17:08:01 发布

最新推荐文章于 2022-11-25 17:08:01 发布 · 107 阅读

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#Hibernate #Java #OpenSource #C #C++

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本文介绍JavaAssist开源框架，该框架简化了Java字节码的操作。通过JavaAssist可以在源代码级别和字节码级别操纵Java行为，例如实现懒加载和生成PO对象。文章还提供了使用JavaAssist修改特定类方法的具体示例。

javaassist opensource framework is the initials of the"Java Programming Assistant" , it makes Java bytecode manipulation simple and easy. you can manipulate the behaviors of the java the following aspects:
1 soruce code level
2 bytecode level
hibernate use the javaassist to instead to the cglib in version 3.3, its function is similar to the cglib ,it can implement the lazy loading and generate the po objects
for examples:
package antlr;

import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;

public class TestAntlr {

public static void main(String[] args) throws Exception {
ClassPool cp = ClassPool.getDefault();
CtClass cc = cp.get("antlr.Hello");
CtMethod m = cc.getDeclaredMethod("say");
// m.setBody("{System.out.println(\"s\");}");

m.insertBefore("System.out.println(\"ss\");");
Class c = cc.toClass();
Hello h = (Hello)c.newInstance();
h.say();

// ClassPool cp = ClassPool.getDefault();
// CtClass cc = cp.get("java.lang.String");
// CtMethod m = cc.getDeclaredMethod("toString");
//// m.setBody("{System.out.println(\"s\");}");
//
//// m.insertBefore("System.out.println(\"ss\");");
// Class c = cc.toClass();
// String h = (String)c.newInstance();
// h.toString();

}
}

package antlr;

class Hello{
public void say() {
System.out.println("Hello");
}
}