基于Java对于PostgreSQL多层嵌套JSON 字段判重

场景：把复杂的 CommonCondition 条件树以 JSON 形式存入 PostgreSQL，并要求：

• 子条件顺序、

• valueList 重复值、

• 展示用字段（如别名）
  不影响“相同业务逻辑”的判定。
  本文给出一条 Java → PostgreSQL 的端到端可复制方案。

1. 数据库层设计（PostgreSQL）

CREATE TABLE report_condition (
    id        bigserial PRIMARY KEY,
    condition jsonb        NOT NULL,
    signature char(64)     NOT NULL,   -- SHA-256 长度
    created_at timestamptz DEFAULT now()
);

-- 查询时直接按 signature 去重
CREATE UNIQUE INDEX uk_signature ON report_condition(signature);

触发器可选：如果希望完全由 DB 计算签名，可用 plpython3u 调用 Python 归一化脚本；
下文演示 Java 端计算签名后写入，逻辑更清晰。

2. Java 端核心实现

2.1 枚举：白名单字段规则

package com.example.condition;

import java.util.List;

/** 不同业务场景下保留的字段集合 */
public enum ConditionNormalizeRule {
    DEFAULT(List.of("table","field","fieldType","type","logicalOperator","operator","valueList","commonConditions")),
    REPORT (List.of("table","field","type","operator","valueList","commonConditions")), // 去掉 fieldType
    AUDIT  (List.of("table","field","fieldType","type","operator","valueList","commonConditions"));

    private final List<String> whiteList;
    ConditionNormalizeRule(List<String> whiteList) { this.whiteList = whiteList; }
    public List<String> getWhiteList() { return whiteList; }
}

2.2 工具类 ConditionHash

package com.example.condition;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.*;
import org.apache.commons.codec.digest.DigestUtils;

import java.util.*;
import java.util.stream.Collectors;

public final class ConditionHash {

    /** 全局 ObjectMapper，线程安全 */
    private static final ObjectMapper MAPPER = new ObjectMapper()
            .setSerializationInclusion(JsonInclude.Include.NON_NULL) // 忽略 null
            .configure(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS, true); // 键排序

    /**
     * 计算业务等价哈希
     * @param root  待计算的 CommonCondition 树
     * @param rule  决定保留哪些字段的枚举
     * @return      SHA-256 十六进制字符串（64 位）
     */
    public static String sha256(CommonCondition root, ConditionNormalizeRule rule) {
        try {
            JsonNode tree = normalize(MAPPER.valueToTree(root), rule);
            byte[] bytes  = MAPPER.writeValueAsBytes(tree);
            return DigestUtils.sha256Hex(bytes);
        } catch (Exception e) {
            throw new IllegalStateException("compute hash failed", e);
        }
    }

    /* ---------- 私有归一化逻辑 ---------- */

    /** 递归归一化：保留白名单字段 + 去重排序 */
    private static JsonNode normalize(JsonNode node, ConditionNormalizeRule rule) {
        if (node == null || !node.isObject()) return node;

        ObjectNode obj = MAPPER.createObjectNode();
        List<String> white = rule.getWhiteList();

        white.forEach(key -> {
            if (node.has(key)) {
                JsonNode val = node.get(key);
                switch (key) {
                    case "valueList":
                        obj.set(key, normalizeValueList(val));         // 去重+排序
                        break;
                    case "commonConditions":
                        obj.set(key, normalizeChildren(val, rule));    // 递归+排序
                        break;
                    default:
                        obj.set(key, val);                             // 直接保留
                }
            }
        });
        return obj;
    }

    /** valueList 去重+字典序排序 */
    private static JsonNode normalizeValueList(JsonNode listNode) {
        if (listNode == null || !listNode.isArray()) return MAPPER.createArrayNode();
        List<String> list = MAPPER.convertValue(listNode, new TypeReference<>() {});
        list = list.stream().distinct().sorted().collect(Collectors.toList());
        return MAPPER.valueToTree(list);
    }

    /** commonConditions 递归归一化后按字符串排序 */
    private static JsonNode normalizeChildren(JsonNode childrenNode, ConditionNormalizeRule rule) {
        if (childrenNode == null || !childrenNode.isArray()) return MAPPER.createArrayNode();
        List<CommonCondition> children = MAPPER.convertValue(childrenNode, new TypeReference<>() {});
        List<JsonNode> sorted = children.stream()
                .map(c -> normalize(MAPPER.valueToTree(c), rule))
                .sorted(Comparator.comparing(JsonNode::toString)) // 稳定排序
                .collect(Collectors.toList());
        return MAPPER.valueToTree(sorted);
    }

    private ConditionHash() {}
}

3. 使用示例

3.1 构造两个“业务等价”的对象

CommonCondition condA = CommonCondition.builder()
        .type("logical")
        .logicalOperator("AND")
        .commonConditions(List.of(
                CommonCondition.builder()
                        .type("base")
                        .table("user")
                        .field("age")
                        .operator("GT")
                        .valueList(List.of("18", "18", "20"))  // 重复值
                        .build(),
                CommonCondition.builder()
                        .type("base")
                        .table("user")
                        .field("status")
                        .operator("IN")
                        .valueList(List.of("ACTIVE", "LOCKED"))
                        .build()
        ))
        .build();

/* 把子条件顺序颠倒，再加一个别名字段，但业务含义不变 */
CommonCondition condB = CommonCondition.builder()
        .type("logical")
        .logicalOperator("AND")
        .tableNameAlias("u")            // 展示用，不参与哈希
        .commonConditions(List.of(
                CommonCondition.builder()
                        .type("base")
                        .table("user")
                        .field("status")
                        .operator("IN")
                        .valueList(List.of("LOCKED", "ACTIVE", "ACTIVE")) // 重复+乱序
                        .build(),
                CommonCondition.builder()
                        .type("base")
                        .table("user")
                        .field("age")
                        .operator("GT")
                        .valueList(List.of("20", "18"))   // 乱序
                        .build()
        ))
        .build();

3.2 计算哈希并判重

String sigA = ConditionHash.sha256(condA, ConditionNormalizeRule.DEFAULT);
String sigB = ConditionHash.sha256(condB, ConditionNormalizeRule.DEFAULT);

System.out.println("sigA = " + sigA);
System.out.println("sigB = " + sigB);
System.out.println("same = " + sigA.equals(sigB));   // true

3.3 插入 PostgreSQL

String sql = """
    INSERT INTO report_condition(condition, signature)
    VALUES (?::jsonb, ?)
    ON CONFLICT (signature) DO NOTHING
    """;
try (PreparedStatement ps = conn.prepareStatement(sql)) {
    ps.setString(1, new ObjectMapper().writeValueAsString(condA));
    ps.setString(2, sigA);
    ps.executeUpdate();
}

ON CONFLICT (signature) DO NOTHING 利用唯一索引实现幂等写入，天然判重。

4. 性能 & 扩展

缓存示例（Lombok）：

@Getter(lazy = true)
private final String hash = ConditionHash.sha256(this, ConditionNormalizeRule.DEFAULT);

5. 小结

1. 数据库：JSONB + 唯一索引 signature，一行 SQL 完成判重。

2. Java：ConditionHash.sha256(root, rule) 统一出口，顺序、重复、别名全部抹平。

3. 枚举：新增业务场景只需再加一个 ConditionNormalizeRule 值，零侵入。