<bean id="demoService" class="lu.tool.provider.DemoServiceImpl" />
<rpc:service interface="lu.tool.provider.DemoService" ref="demoService" />
 ^                 ^                                   ^
 |- xsd:element    |- xsd:attribute                    |- xsd:attribute

XML Schema Definition

由motan.xsd简化而来rpc.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns="http://tool.lu/schema/rpc"
            xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            xmlns:tool="http://www.springframework.org/schema/tool"
            xmlns:beans="http://www.springframework.org/schema/beans"
            targetNamespace="http://tool.lu/schema/rpc">
    <xsd:import namespace="http://www.w3.org/XML/1998/namespace"/>
    <xsd:import namespace="http://www.springframework.org/schema/tool"/>
    <xsd:import namespace="http://www.springframework.org/schema/beans"/>

    <xsd:complexType name="abstractConfig">
        <xsd:choice minOccurs="0" maxOccurs="unbounded">
            <xsd:element ref="beans:property" minOccurs="0" maxOccurs="unbounded"/>
        </xsd:choice>
        <xsd:anyAttribute namespace="##other" processContents="lax"/>
    </xsd:complexType>

    <xsd:element name="service">
        <xsd:complexType>
            <xsd:complexContent>
                <xsd:extension base="abstractConfig">
                    <xsd:attribute name="interface" type="xsd:token">
                        <xsd:annotation>
                            <xsd:documentation>
                                <![CDATA[ interface. ]]>
                            </xsd:documentation>
                            <xsd:appinfo>
                                <tool:annotation>
                                    <tool:expected-type type="java.lang.Class"/>
                                </tool:annotation>
                            </xsd:appinfo>
                        </xsd:annotation>
                    </xsd:attribute>
                    <xsd:attribute name="ref" type="xsd:string" use="optional">
                        <xsd:annotation>
                            <xsd:documentation>
                                <![CDATA[ bean id ]]>
                            </xsd:documentation>
                        </xsd:annotation>
                    </xsd:attribute>
                </xsd:extension>
            </xsd:complexContent>
        </xsd:complexType>
    </xsd:element>
</xsd:schema>

NamespaceHandler

public class RpcNamespaceHandler extends NamespaceHandlerSupport {

    @Override
    public void init() {
        registerBeanDefinitionParser("service", new RpcBeanDefinitionParser(ServiceConfigBean.class));
    }
}

BeanDefinitionParser

未完待续...

public class RpcBeanDefinitionParser implements BeanDefinitionParser {

    private final Class<?> beanClass;

    public RpcBeanDefinitionParser(Class<?> beanClass) {
        this.beanClass = beanClass;
    }

    @Override
    public BeanDefinition parse(Element element, ParserContext parserContext) {
        // 具体逻辑
    }
}

定义接口

public interface RoundRobin<T> {

    T nextData();

}

实现

算法来自nginx

public class WeightedRoundRobin<T> implements RoundRobin<T> {

    private List<Item<T>> items = new ArrayList<>();

    public WeightedRoundRobin(Map<T, Integer> datas) {
        List<Item<T>> initItems = datas.entrySet()
                .stream()
                .map(e -> new Item<>(e.getKey(), e.getValue()))
                .collect(Collectors.toList());
        items.addAll(initItems);
    }

    public T nextData() {
        Item<T> bestItem = null;
        int total = 0;
        for (Item<T> currentItem : items) {
            currentItem.currentWeight += currentItem.effectiveWeight;
            total += currentItem.effectiveWeight;
            if (currentItem.effectiveWeight < currentItem.weight) {
                currentItem.effectiveWeight++;
            }
            if (bestItem == null || currentItem.currentWeight > bestItem.currentWeight) {
                bestItem = currentItem;
            }
        }
        if (bestItem == null) {
            return null;
        }
        bestItem.currentWeight -= total;
        return bestItem.getData();
    }

    public List<Item<T>> getItems() {
        return items;
    }

    public void setItems(List<Item<T>> items) {
        this.items = items;
    }

    public static final class Item<T> {

        private T data;
        private int weight;
        private int effectiveWeight;
        private int currentWeight;

        public Item(T data, int weight) {
            this.data = data;
            this.weight = weight;
        }

        public T getData() {
            return data;
        }

        public void setData(T data) {
            this.data = data;
        }

        public int getWeight() {
            return weight;
        }

        public void setWeight(int weight) {
            this.weight = weight;
        }

        public int getEffectiveWeight() {
            return effectiveWeight;
        }

        public void setEffectiveWeight(int effectiveWeight) {
            this.effectiveWeight = effectiveWeight;
        }

        public int getCurrentWeight() {
            return currentWeight;
        }

        public void setCurrentWeight(int currentWeight) {
            this.currentWeight = currentWeight;
        }

        @Override
        public String toString() {
            return "Item{" +
                    "data=" + data +
                    ", weight=" + weight +
                    ", effectiveWeight=" + effectiveWeight +
                    ", currentWeight=" + currentWeight +
                    '}';
        }
    }

}

使用

        Map<Integer, Integer> testDatas = new HashMap<Integer, Integer>() {{
            put(1, 3); // 权重3
            put(2, 5); // 权重5
            put(3, 8); // 权重8
        }};
        WeightedRoundRobin<Integer> roundRobin = new WeightedRoundRobin<>(testDatas);

        for (int i = 0; i < 20; i++) {
            LOGGER.info("id: {}", roundRobin.nextData());
        }