java - 如何在json比较中跳过一个节点

Question

我有一个 json 比较器

class JSONUtils {

public static void areEqual(def context_1, def context_2) {
    Object obj1,obj2;
    Object json = new JSONTokener(context_1).nextValue();
    if (json instanceof JSONObject) {
        obj1 = new JSONObject(context_1);
        obj2 = new JSONObject(context_2);
    } else if (json instanceof JSONArray) {
        obj1 = new JSONArray(context_1);
        obj2 = new JSONArray(context_2);
    }
    def ObjectMapper mapper = new ObjectMapper();
    def JsonNode tree1 = mapper.readTree(obj1.toString());
    def JsonNode tree2 = mapper.readTree(obj2.toString());
    assert tree1.equals(tree2);
   }
 }

当两个 json 完全相同时，这会很好地工作。我有一个特殊情况，我需要在比较时跳过或忽略两个节点值。

例子:

First Json:
{
   "rd":12,
   "td":"text1"
   "dt": 123456,
   "vt": "west"
}
Second Json:
{
   "rd":12,
   "td":"text1"
   "dt": 333333,
   "vt": "east"
}

我需要忽略或跳过“dt”和“vt”比较。

我该如何实现。

Answer 1

创建自定义 POJO 来保存您关心的值:

// Ignore fields "dt" and "vt"
@JsonIgnoreProperties(ignoreUnknown = true)
public class MyType {
    // Ideally these should use getters/setters
    public int rd;
    public String td;

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof MyType) {
            MyType t = (MyType)obj;
            return t.rd == this.rd
                    && Objects.equals(t.td, this.td);
        }
        return false;
    }

    // hashCode() should always be overriden alongside equals()
    @Override
    public int hashCode() {
        return Objects.hash(rd, td);
    }
}

在您的代码中，您可以像这样构造和比较它们:

ObjectMapper mapper = new ObjectMapper();
MyType t1 = mapper.readValue(obj1.toString(), MyType.class);
MyType t2 = mapper.readValue(obj2.toString(), MyType.class);
assert t1.equals(t2);

---

根据我们在评论中的讨论，这里有一个使用 Guava 库比较任意两个 JSON 对象同时过滤掉任意一组键的通用解决方案:

public static boolean jsonEquals(String json1, String json2, String... ignoreKeys) throws IOException {
    // this is a Guava Predicate
    Predicate<String> filter = Predicates.not(Predicates.in(Sets.newHashSet(ignoreKeys)));

    ObjectMapper mapper = new ObjectMapper();
    Map<String, Object> object1 = Maps.filterKeys(mapper.readValue(json1, Map.class), filter);
    Map<String, Object> object2 = Maps.filterKeys(mapper.readValue(json2, Map.class), filter);
    return object1.equals(object2);
}