JSON Patch java库之zjsonpatch

àì夳堔傛蜴生んèń 2021-09-02 03:49 391阅读 0赞

### 介绍 ###

zjsonpatch是用Java编写的[RFC 6902][] JSON Patch的实现。github地址：[https://github.com/flipkart-incubator/zjsonpatch][https_github.com_flipkart-incubator_zjsonpatch]

**1、描述：**

*  实现了RFC 6902 JSON Patch标准的java库；
 *  避免仅更改一部分json文档时发送整个json文档的情况，从而降低了网络带宽需求；
 *  当与[RFC 5789][] HTTP PATCH的HTTP PATCH方法结合使用时，它将以标准方式对HTTP API进行部分更新。

**2、功能：**

*  获取两个json文档的diff信息，并以这个diff信息作为patch（使用json来描述，包含了op、patch、value）；
 *  可以将一个patch，作用在一个json文档上；

根据上篇blog（[https://blog.csdn.net/liuxiao723846/article/details/108508200][https_blog.csdn.net_liuxiao723846_article_details_108508200]）可知，RFC 6902 JSON Patch标准定义了以下五种operations：add、remove、replace、move、copy

### 示例 ###

maven pom.xml：

<groupId>com.flipkart.zjsonpatch</groupId>
    <artifactId>zjsonpatch</artifactId>
    <version>{version}</version>

这里使用了最新版本0.4.11，可以通过[https://search.maven.org/search?q=g:com.flipkart.zjsonpatch][https_search.maven.org_search_q_g_com.flipkart.zjsonpatch] 查找对应的版本，也可以在github 上的release上找对应的版本[https://github.com/flipkart-incubator/zjsonpatch/releases][https_github.com_flipkart-incubator_zjsonpatch_releases]

**1、获取json diff信息作为patch：**

public class PatchTest {
        private static final ObjectMapper mapper = new ObjectMapper();
        private static String json1 = "{\"a\":0,\"b\":[1,2]}";
        private static String json2 = "{\"b\": [1,2,0]} ";
    
        public static void main(String... str) {
    
            //JsonNode patch = JsonDiff.asJson(JsonNode source, JsonNode target)
            JsonNode patch = JsonDiff.asJson(mapper.readTree(json1),mapper.readTree(json2));
    
            System.out.println(patch.toPrettyString());
        }

输出：\[\{"op":"move","from":"/a","path":"/b/2"\}\]

**2、关闭move、copy operations：**

上面的输出可以看到，默认情况下计算两个json文档的diff（patch）信息时会使用move、copy这样的operations，虽然这两个operations很有用，但实际业务中有时不需要这样，只想表达成最简单的add、remove、replace这种operations。

private static EnumSet<DiffFlags> flags = DiffFlags.dontNormalizeOpIntoMoveAndCopy().clone();
    
    JsonNode patch = JsonDiff.asJson(mapper.readTree(json1),mapper.readTree(json2),flags );

输出：\[\{"op":"remove","path":"/a","value":0\},\{"op":"add","path":"/b/2","value":0\}\]

**3、应用patch：**

通过diff计算出来的patch，可以应用到一个json文档上，并返回patch后的json文档。这个过程是对原json文档的一个克隆，所以不会修改原sjon文档的内容。

public class PatchTest {
        private static final ObjectMapper mapper = new ObjectMapper();
        private static EnumSet<DiffFlags> flags = DiffFlags.dontNormalizeOpIntoMoveAndCopy().clone();
    
        private static String json1 = "{\"a\":0,\"b\":[1,2]}";
        private static String json2 = "{\"b\": [1,2,0]} ";
    
        public static void main(String... str) {
    
            //JsonNode patch = JsonDiff.asJson(JsonNode source, JsonNode target)
            JsonNode patch = JsonDiff.asJson(mapper.readTree(json1),mapper.readTree(json2));
            //System.out.println(patch.toPrettyString());
    
            //JsonNode target = JsonPatch.apply(JsonNode patch, JsonNode source);
            JsonNode target = JsonPatch.apply(patch, mapper.readTree(json1));
            System.out.println(target .toPrettyString());
        }

输出：\{"b":\[1,2,0\]\}

[RFC 6902]: http://tools.ietf.org/html/rfc6902
[https_github.com_flipkart-incubator_zjsonpatch]: https://github.com/flipkart-incubator/zjsonpatch
[RFC 5789]: http://tools.ietf.org/html/rfc5789
[https_blog.csdn.net_liuxiao723846_article_details_108508200]: https://blog.csdn.net/liuxiao723846/article/details/108508200
[https_search.maven.org_search_q_g_com.flipkart.zjsonpatch]: https://search.maven.org/search?q=g:com.flipkart.zjsonpatch
[https_github.com_flipkart-incubator_zjsonpatch_releases]: https://github.com/flipkart-incubator/zjsonpatch/releases