一 定义策略类接口

java">
import org.jetbrains.annotations.NotNull;

import javax.annotation.Nullable;

public interface ApprovalStrategy<T> {

    /**
     * 返回需要的类型 不能为空
     *
     * @return
     */
    @NotNull
    Class<T> getSupportedType();

    void handlePass(T businessId, @Nullable String comment);

    void handleReject(T businessId, String comment);
}

二 定义Context

java">import lombok.AllArgsConstructor;
import org.springframework.lang.Nullable;
import org.springframework.stereotype.Component;

import java.util.Map;

@AllArgsConstructor
@Component
public class ApprovalContext {

    private final Map<String, ApprovalStrategy<?>> strategies;


    public <T> void executePass(String type, T businessId, @Nullable String comment) {
        ApprovalStrategy<T> strategy = getStrategyWithValidation(type);
        strategy.handlePass(convertBusinessId(strategy, businessId), comment);
    }


    public <T> void executeReject(String type, T businessId, String comment) {
        ApprovalStrategy<T> strategy = getStrategyWithValidation(type);
        strategy.handleReject(convertBusinessId(strategy, businessId), comment);
    }

    private <T> ApprovalStrategy<T> getStrategyWithValidation(String type) {
        @SuppressWarnings("unchecked")
        ApprovalStrategy<T> strategy = (ApprovalStrategy<T>) strategies.get(type);
        if (strategy == null) {
            throw new IllegalArgumentException("未知的审批类型：" + type);
        }
        return strategy;
    }

    private <T> T convertBusinessId(ApprovalStrategy<T> strategy, Object businessId) {
        Class<T> supportedType = strategy.getSupportedType();
        if (supportedType == null) {
            throw new NullPointerException("supportedType 不能为空");
        }
        if (!supportedType.isInstance(businessId)) {
            if (supportedType == Integer.class && businessId instanceof String) {
                return supportedType.cast(Integer.valueOf((String) businessId));
            } else {
                throw new IllegalArgumentException(
                        "不支持的类型转换：" + businessId.getClass() + " 到 " + supportedType
                );
            }
        }
        return supportedType.cast(businessId);
    }


}

三 实现类

java">
@Component("TEST_REVIEW")
@RequiredArgsConstructor
public class TestApproval implements ApprovalStrategy<Integer> {

    @Override
    public void handlePass(Integer businessId, @Nullable String comment) {

    }

    @Override
    public void handleReject(Integer businessId, String comment) {

    }

    @NotNull
    @Override
    public Class<Integer> getSupportedType() {
        return Integer.class;
    }
}

这里TEST_REVIEW为ApprovalType枚举中的常量字符 利用spring将其收集到ApprovalContext类的strategies中

使用：

1 注入private final ApprovalContext approvalContext;
2 approvalContext.executePass(ApprovalType.TEST_REVIEW.name(), id, null);
|| approvalContext.executeReject(ApprovalType.TEST_REVIEW.name(), id, null);
这里可以用个枚举 来规范调用