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JAVA认证基础知识：基于反射机制的服务代理调用
实现原理：通过传递服务bean的名称、执行的方法及参数，通过反射机制进行调用返回。
优点：只需对外提供一个接口服务即可，只要容器中操作服务bean,通过接口即可调用，增加服务bean无需增加对外接口。
代码如下：
接口类
public interface ProxyService {
/**
* webservice调用代理
* @param beanName bean或类名
* @param functionName 调用的函数名
* @param params 参数
* @return
* @throws Exception
*/
Object proxy(String beanName, String functionName,String… params) throws Exception;
}
实现类：
服务基于spring,为了方便获取服务bean,实现类实现spring的ApplicationContextAware接口
@Service
public class ProxyServiceImpl implements ProxyService ,ApplicationContextAware{
protected final Logger logger = LoggerFactory.getLogger(getClass());
@Resource
private ApplicationContext applicationContext;
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
/**
* 通过代理执行业务方法，方法数据
*/
@SuppressWarnings("rawtypes")
@Override
public Object proxy(String beanName, String functionName, String… params) throws ServiceException {
//参数判断
if(StringUtils.isEmpty(beanName)){
throw new Exception("error: beanName is empty.");
}
if(StringUtils.isEmpty(functionName)){
throw new Exception("error: functionName is empty.");
}
//获取服务bean
Object bean = getBean(beanName);
if(bean == null){
throw new Exception("error: bean is not exist.");
}
if(params == null || params.length ==0){
logger.warn("proxy params is empty.");
}
Method method = null;
//处理无参数调用
if(params == null || params.length ==0){
try {
//获取服务bean方法
method = bean.getClass()。getMethod(functionName);
} catch (SecurityException e) {
logger.error("proxy getMethod SecurityException:"+e.getMessage());
e.printStackTrace();
} catch (Exception e) {
logger.error("proxy invoke IllegalArgumentException:"+e.getMessage());
e.printStackTrace();
throw new Exception("error: get method Exception:"+e.getMessage());
}
}else{
//处理有参数调用
//处理调用方法参数
Class[] paraTypes = new Class[params.length];
for (int i = 0; i < paraTypes.length; i++) {
paraTypes[i] = String.class;
}
//获取服务bean方法
method = bean.getClass()。getMethod(functionName, paraTypes);
}catch (Exception e) {
logger.error("proxy invoke IllegalArgumentException:"+e.getMessage());
e.printStackTrace();
throw new Exception("error: get method Exception:"+e.getMessage());
}
}
if(method == null ){
throw new Exception("error: function is not exist.");
}
Object rs = null;
try {
//调用返回数据
rs = method.invoke(bean,params);
} catch (Exception e) {
logger.error("proxy invoke IllegalArgumentException:"+e.getMessage());
e.printStackTrace();
throw new Exception("error: invoke method Exception:"+e.getMessage());
}
return rs;
}
/**
* 获取bean对象
* @param beanName
* @return
*/
private Object getBean(String beanName){
Object bean = null;
bean = applicationContext.getBean(beanName);
if(bean == null){
try {
Class classe = Class.forName(beanName);
bean = classe.newInstance();
} catch (InstantiationException e) {
logger.error("getBean InstantiationException:"+e.getMessage());
e.printStackTrace();
} catch (IllegalAccessException e) {
logger.error("getBean IllegalAccessException:"+e.getMessage());
e.printStackTrace();
}catch ( ClassNotFoundException e) {
logger.error("getBean ClassNotFoundException:"+e.getMessage());