/** * {@link ThriftFieldMetadata}的代理类， * 重载{@link #getrequiredness()}方法，根据参数类型对返回值进行修改 * @author guyadong * */
@Immutable
public class DecoratorThriftFieldMetadata extends ThriftFieldMetadata {
    private static final Logger logger = Logger.getLogger(DecoratorThriftFieldMetadata.class.getName());
    private static Boolean primitiveOptional = null;
    /** * {@link DecoratorThriftFieldMetadata}缓存对象,* 保存每个{@link ThriftFieldMetadata}对应的{@link DecoratorThriftFieldMetadata}实例 */
    private static final LoadingCache<ThriftFieldMetadata,DecoratorThriftFieldMetadata> 
        FIELDS_CACHE = 
            CacheBuilder.newBuilder().build(
                    new CacheLoader<ThriftFieldMetadata,DecoratorThriftFieldMetadata>(){
                        @Override
                        public DecoratorThriftFieldMetadata load(ThriftFieldMetadata key) throws Exception {
                            return new DecoratorThriftFieldMetadata(key);
                        }});
    /** 将{@link ThriftFieldMetadata}转换为 {@link DecoratorThriftFieldMetadata}对象 */
    public static  final Function<ThriftFieldMetadata,ThriftFieldMetadata> 
        FIELD_TRANSFORMER = 
            new Function<ThriftFieldMetadata,ThriftFieldMetadata>(){
                @Nullable
                @Override
                public ThriftFieldMetadata apply(@Nullable ThriftFieldMetadata input) {
                    return null == input || input instanceof DecoratorThriftFieldMetadata  
                            ? input 
                            : FIELDS_CACHE.getUnchecked(input);
                }};
    private final Type javaType;
    private DecoratorThriftFieldMetadata(ThriftFieldMetadata input){
        super(
                input.getId(),input.getrequiredness(),input.getThriftType(),input.getName(),input.getType(),input.getInjections(),input.getConstructorInjection(),input.getMethodInjection(),input.getExtraction(),input.getCoercion());
        // 获取field的类型
        List<ThriftInjection> injections = getInjections();
        checkState(injections.size()>0,"invalid size of injections");
        ThriftInjection injection = injections.get(0);      
        if(injection instanceof ThriftParameterInjection){
            javaType = ((ThriftParameterInjection)injection).getJavaType();
        }else if(injection instanceof ThriftFieldInjection){
            javaType = ((ThriftFieldInjection)injection).getField().getType();
        }else{
            javaType = null;
            // 对于不支持的数据类型无法获取field类型，输出警告
            logger.warning(
                    String.format("UNSUPPORED TYPE %s，can't get Java Type. "
                            + "(不识别的ThriftInjection实例类型，无法实现requiredness转义)",null == injection? null : injection.getClass().getName()));
        }
    }
    /** 重载方法,实现 requiredness 转义 */
    @Override
    public requiredness getrequiredness() {
        requiredness requiredness = super.getrequiredness();
        checkState(requiredness.UNSPECIFIED != requiredness);
        // 当为primitive类型时，requiredness 为required
        // 当为primitive类型的Object封装类型时(Long,Integer,Boolean)，requiredness为OPTIONAL
        if( !Boolean.FALSE.equals(primitiveOptional)
                && javaType instanceof Class<?>
                && requiredness == requiredness.NONE){
            Class<?> parameterClass = (Class<?>)javaType;
            if(parameterClass.isPrimitive()){
                requiredness = requiredness.required;
                // logger.info(String.format("%s %s",parameterClass.getSimpleName(),requiredness));
            }else if(Primitives.isWrapperType(parameterClass)){
                requiredness = requiredness.OPTIONAL;
                // logger.info(String.format("%s %s",requiredness));
            }
        }
        return requiredness;
    }
    /** * 设置optional标记<br> * 指定{@link #getrequiredness}方法调用时是否对primitive类型及其封装类型(Integer,Long)参数的返回值进行替换<br> * 默认值:{@code true}<br> * 该方法只能被调用一次 * @param optional * @see #getrequiredness() * @throws IllegalStateException 方法已经被调用 */
    public static synchronized void setPrimitiveOptional(boolean optional) {
        checkState(null == DecoratorThriftFieldMetadata.primitiveOptional,"primitiveOptional is initialized already.");
        DecoratorThriftFieldMetadata.primitiveOptional = optional;
    }
}

偷天换日

有了上面的decorator，要让它发挥做用，还要做进一步的工作，需要用将原本对ThriftFieldMetadata@H_403_125@的访问请求转向这个新的对象，以服务方法为例 ，我们同样需要写一个ThriftMethodMetadata@H_403_125@的代理类。重载getParameters()@H_403_125@方法，在这里完成对象转换(请求重定向)。
代码如下:

/** * 重载{@link #getParameters()}方法,用{@link DecoratorThriftFieldMetadata}替换{@link ThriftFieldMetadata} * @author guyadong * */
@Immutable
public class ThriftMethodMetadataCustom extends ThriftMethodMetadata {
    private final List<ThriftFieldMetadata> parameters;
    public ThriftMethodMetadataCustom(String serviceName,Method method,ThriftCatalog catalog)
    {
        super(serviceName,method,catalog);
        parameters = Lists.transform(super.getParameters(),DecoratorThriftFieldMetadata.requirednessTransformer);
        // 这里用到了定义在DecoratorThriftFieldMetadata 中的 Function常量
    }

    @Override
    public List<ThriftFieldMetadata> getParameters()
    {
        // 返回转换成DecoratorThriftFieldMetadata类型的参数对象表
        return parameters;
    }
}

/** * {@link ThriftStructMetadata}的代理类<br> * 重载所有{@link ThriftFieldMetadata}相关方法 * @author guyadong * */
@Immutable
public class DecoratorThriftStructMetadata extends ThriftStructMetadata {
    /** {@link DecoratorThriftStructMetadata}缓存对象,* 保存每个{@link ThriftStructMetadata}对应的{@link DecoratorThriftStructMetadata}实例 */
    private static final LoadingCache<ThriftStructMetadata,DecoratorThriftStructMetadata> 
        STRUCTS_CACHE = 
            CacheBuilder.newBuilder().build(
                    new CacheLoader<ThriftStructMetadata,DecoratorThriftStructMetadata>(){
                        @Override
                        public DecoratorThriftStructMetadata load(ThriftStructMetadata key) throws Exception {
                            return new DecoratorThriftStructMetadata(key);
                        }});
    /** 将{@link ThriftStructMetadata}转换为 {@link DecoratorThriftStructMetadata}对象 */
    public static final Function<ThriftStructMetadata,ThriftStructMetadata> 
        STRUCT_TRANSFORMER = new Function<ThriftStructMetadata,ThriftStructMetadata>(){
            @Nullable
            @Override
            public ThriftStructMetadata apply(@Nullable ThriftStructMetadata input) {
                return null == input || input instanceof DecoratorThriftStructMetadata
                        ? input
                        : STRUCTS_CACHE.getUnchecked(input);
            }};
    private DecoratorThriftStructMetadata(ThriftStructMetadata input){
        super(input.getStructName(),input.getStructType(),input.getBuilderType(),input.getMetadataType(),input.getBuilderMethod(),input.getDocumentation(),ImmutableList.copyOf(input.getFields()),input.getMethodInjections());
    }
    @Override
    public ThriftFieldMetadata getField(int id) {
        return DecoratorThriftFieldMetadata.FIELD_TRANSFORMER.apply(super.getField(id));
    }

    @Override
    public Collection<ThriftFieldMetadata> getFields() {
        return Collections2.transform(super.getFields(),DecoratorThriftFieldMetadata.FIELD_TRANSFORMER);
    }

    @Override
    public Collection<ThriftFieldMetadata> getFields(FieldKind type) {
        return Collections2.transform(super.getFields(type),DecoratorThriftFieldMetadata.FIELD_TRANSFORMER);
    }

}

<dependency>
    <groupId>com.gitee.l0km</groupId>
    <artifactId>swift2thrift-maven-plugin</artifactId>
    <version>1.7</version>
</dependency>

<dependency>
    <groupId>com.gitee.l0km</groupId>
    <artifactId>swift2thrift-maven-plugin</artifactId>
    <version>1.7</version>
</dependency>