November 14th, 2007通过Annotation和Struts2的interceptor实现向Action中注入jndi资源
为了实现向struts2的Action中注入ejb3，我写了一个Annotation用来定义要注入哪个ejb3，又写了一个struts2的interceptor用来实施注入。Annotation代码如下：
@Retention(value=RetentionPolicy.RUNTIME) @Target(value={ElementType.METHOD}) @Inherited public @interface JndiLookup { String jndi(); Class type(); }
Interceptor代码如下：
public class JndiLookupInterceptor implements Interceptor { private InitialContext contaxt; public void destroy() { ; } public void init() { try { contaxt = new InitialContext(); } catch (NamingException e) { e.printStackTrace(); } } public String intercept(ActionInvocation invocation) throws Exception { Method[] methods = invocation.getAction() .getClass().getMethods(); for(Method method : methods) { try{ Class[] parameterTypes = method.getParameterTypes(); if(parameterTypes.length != 1) { continue; } JndiLookup jndiLookup = method.getAnnotation(JndiLookup.class); if(jndiLookup == null) { continue; } if(jndiLookup.jndi() == null || jndiLookup.jndi().length() == 0) { continue; } if(jndiLookup.type() == null) { continue; } Object object = this.contaxt.lookup(jndiLookup.jndi()); method.invoke(invocation.getAction(), new Object[] {jndiLookup.type().cast(object)}); } catch (Exception e) { e.printStackTrace(); ; } } return invocation.invoke(); } }
需要被注入的Action代码如下：
public class SomeAction { private DataSource ds; @JndiLookup(jndi="jdbc/mysqlDS", type=DataSource.class) public void setDs(DataSource ds) { this.ds = ds; } public String execute() { //do something about the ds } }
经测试，在tomcat下注入DataSource成功了。看来Annotation和Struts2真的是个好东西呀！
