CGLib(Code Generation Library)是一个强大的,高性能,高质量的字节码操作类库,它可以在运行期扩展Java类与实现Java接口,Spring、Hibernate等很多著名的框架都使用了它。
[url=https://github.com/cglib/cglib/]https://github.com/cglib/cglib/[/url]
其他的库还有:
[url=http://www.csg.ci.i.u-tokyo.ac.jp/~chiba/javassist/]Javassist (Java Programming Assistant)[/url]、[url=http://asm.ow2.org/]ASM[/url]、[url=http://commons.apache.org/proper/commons-bcel/]Apache Commons BCEL(Byte Code Engineering Library)[/url]
[b]运行结果:[/b]
[quote]id : [999] createdAt : [Mon May 31 00:00:00 CST 2010][/quote]
[url=https://github.com/cglib/cglib/]https://github.com/cglib/cglib/[/url]
其他的库还有:
[url=http://www.csg.ci.i.u-tokyo.ac.jp/~chiba/javassist/]Javassist (Java Programming Assistant)[/url]、[url=http://asm.ow2.org/]ASM[/url]、[url=http://commons.apache.org/proper/commons-bcel/]Apache Commons BCEL(Byte Code Engineering Library)[/url]
public class CGLibExample {
@SuppressWarnings("unchecked")
public static void main(String[] args) {
// 定义一个参数是字符串类型的setCreatedAt方法
InterfaceMaker im = new InterfaceMaker();
im.add(new Signature("setCreatedAt", Type.VOID_TYPE,
new Type[] { Type.getType(String.class) }), null);
Class myInterface = im.create();
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(ExampleBean.class);
enhancer.setInterfaces(new Class[] { myInterface });
enhancer.setCallback(new MethodInterceptor() {
public Object intercept(Object obj, Method method, Object[] args,
MethodProxy proxy) throws Throwable {
ExampleBean bean = (ExampleBean) obj;
// 调用字符串类型的setCreatedAt方法时,转换成Date型后调用Setter
if (method.getName().startsWith("setCreatedAt")
&& args[0] != null && args[0] instanceof String) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
Date date = null;
try {
date = sdf.parse((String) args[0]);
} catch (final Exception e) { /* nop */ }
bean.setCreatedAt(date);
return null;
}
return proxy.invokeSuper(obj, args);
}
});
// 生成一个Bean
ExampleBean bean = (ExampleBean) enhancer.create();
bean.setId(999);
try {
Method method = bean.getClass().getMethod("setCreatedAt", new Class[] {String.class});
method.invoke(bean, new Object[]{"20100531"});
} catch (final Exception e) {
e.printStackTrace();
}
System.out.printf("id : [%d] createdAt : [%s]\n", bean.getId(), bean.getCreatedAt());
}
}
class ExampleBean implements Serializable {
private static final long serialVersionUID = -8121418052209958014L;
private int id;
private Date createdAt;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public Date getCreatedAt() {
return createdAt;
}
public void setCreatedAt(Date createdAt) {
this.createdAt = createdAt;
}
}
[b]运行结果:[/b]
[quote]id : [999] createdAt : [Mon May 31 00:00:00 CST 2010][/quote]