resteasy自定义参数解析

• InjectorFactory：负责创建注入的工厂，比如ValueInject、MethodInjector
• ValueInjector：处理参数解析
  要扩展自定义的参数解析，基本思路是这样，使用特定的InejectorFactory创建自定义的ValueInjector。
  resteasy框架允许我们使用自已的InjectorFactory，默认是使用InjectorFactoryImpl。如果我们想改变其默认实现，需要在web.xml中指定具体的实现类，这部分的源码在ConfigurationBootstrap#createDeployment方法中，支持自定义的InjectorFactory

web.xml
 param>
    <param-name>resteasy.injector.factoryparam-name>
    <param-value>net.dwade.plugins.resteasy.PaymentInjectorFactoryparam-value>
 param>

编写PaymentInjectorFactory实现类，继承InjectorFactoryImpl，重写createParameterExtractor方法，返回自定义的ValueInjector实现类。

PaymentInjectorFactory.java
/**
* 扩展resteasy的{@link InjectorFactory}，用于实现自定义参数解析、参数验证，
* 如果使用{@link SpringResteasyBootstrap}作为ServletContextListener启动，默认会使用该InjectorFactory，
* 否则需要在web.xml中指定resteasy.injector.factory参数, eg:
* 
* <context-param>
*    <param-name>resteasy.injector.factory</param-name>
*    <param-value>com.sitech.miso.payment.common.support.rest.PaymentInjectorFactory</param-value>
* </context-param>
* 
* @see SpringResteasyBootstrap
* @see ResteasyBootstrap
* @see ListenerBootstrap#createDeployment()
* @author huangxf
* @date 2017年4月21日
*/
public class PaymentInjectorFactory extends InjectorFactoryImpl {

    @Override
    public ValueInjector createParameterExtractor(Parameter parameter,
            ResteasyProviderFactory providerFactory) {
        boolean isDataBody = hasAnnotation( parameter, RequestDataBody.class );
        if ( isDataBody ) {
            return new RequestDataInjector( parameter, providerFactory );
        }
        return super.createParameterExtractor(parameter, providerFactory);
    }

    /**
    * 返回{@link PaymentMethodInjector}
    */
    @Override
    public MethodInjector createMethodInjector(ResourceLocator method,
            ResteasyProviderFactory factory) {
        return new PaymentMethodInjector( method, factory );
    }


    @SuppressWarnings("rawtypes")
    protected boolean hasAnnotation( Parameter parameter, Class annotation ) {
        Annotation[] annotations = parameter.getAnnotations();
        if ( annotations == null ) {
            return false;
        }
        for ( Annotation anno : annotations ) {
            boolean is = annotation.isInstance( anno );
            if ( is ) {
                return true;
            }
        }
        return false;
    }

}

实现ValueInjector接口，完成参数解析的逻辑，这里以获取json报文中的data节点为例。

RequestDataInjector.java
/**
* 支持resteasy对{@link RequestDataBody}注解的参数解析
* @see RequestDataBody
* @author huangxf
* @date 2017年4月21日
*/
public class RequestDataInjector implements ValueInjector {

    private Parameter paramerter;

    private ResteasyProviderFactory providerFactory;

    private Logger logger = LoggerFactory.getLogger( this.getClass() );

    /**
    * 保存请求json数据的key，value为JSONObject
    */
    public static final String JSON_KEY = RequestDataInjector.class.getName();

    public RequestDataInjector(Parameter parameter,    ResteasyProviderFactory providerFactory) {
        this.paramerter = parameter;
        this.providerFactory = providerFactory;
    }

    @Override
    public Object inject( HttpRequest request, HttpResponse response ) {

        Throwable ex = null;
        try {

            checkJsonRequest( request );

            JSONObject jsonObject = (JSONObject)request.getAttribute( JSON_KEY );

            //说明方法中的参数未被解析，因为可能需要对Sign进行解析
            if ( jsonObject == null  ) {

                //获取请求数据中的json
                String json = JSON.parseObject( request.getInputStream(), StandardCharsets.UTF_8, String.class );
                logger.info( "解析Json数据:{}", json );

                //转换成json对象
                jsonObject = JSONObject.parseObject( json );

                //保存至上下文中，便于其他参数的解析
                request.setAttribute( JSON_KEY, jsonObject );
            }

            //将data节点下面的数据返回
            return jsonObject.getJSONObject( "data" ).toJavaObject( paramerter.getType() );

        } catch ( Exception e ) {
            ex = e;
            logger.warn( "请求参数有误.", e );
        }
        throw new IllegalArgumentException( "Request param error.", ex );
    }

    /**
    * 检验是否传递的是json数据
    */
    protected void checkJsonRequest( HttpRequest request ) {

        String contentType = request.getHttpHeaders().getHeaderString( "Content-Type" );

        //匹配application/json，text/json
        if ( StringUtils.containsIgnoreCase( contentType, "json" ) ) {
            return;
        }
        throw new IllegalArgumentException( "Not json request." );
    }

    @Override
    public Object inject() {
        throw new RuntimeException("Not allowed to inject.");
    }

}