JsonPath的用法
JsonPath的用法
今天有个临时需求，需要将很多json数据添加一个key value。
当听到这个需求，第一眼想到的便是fastjson，构造一堆list，map什么的，感觉特复杂。想着想着突然脑海里飘过XPath，然鹅XPath是基于xml，就百度一下看看有没有json path。居然还真有个JsonPath。。。突然发现自己很孤陋寡闻。
既然有了，那就学习一下，下面就说说今天的使用心得。
一、项目地址
https://github.com/json-path/JsonPath
二、在线测试
看网址像是官方的，可以在线测试表达式，还是蛮好使的
http://jsonpath.com/
三、文档
https://goessner.net/
gradle依赖
// https://mvnrepository.com/artifact/com.jayway.jsonpath/json-path
compile group: 'com.jayway.jsonpath', name: 'json-path', version: '2.4.0'
操作符
| XPath | JSONPath | Description |
|---|---|---|
| / | $ | the root object/element |
| . | @ | the current object/element |
| / | . or [] | child operator |
| .. | n/a | parent operator |
| // | .. | recursive descent. JSONPath borrows this syntax from E4X. |
| * | * | wildcard. All objects/elements regardless their names. |
| @ | n/a | attribute access. JSON structures don’t have attributes. |
| [] | [] | subscript operator. XPath uses it to iterate over element collections and for predicates. In Javascript and JSON it is the native array operator. |
| | | [,] | Union operator in XPath results in a combination of node sets. JSONPath allows alternate names or array indices as a set. |
| n/a | [start: end:step] | array slice operator borrowed from ES4. |
| [] | ?() | applies a filter (script) expression. |
| n/a | () | script expression, using the underlying script engine. |
| () | n/a | grouping in Xpath |
运算符
| XPath | JSONPath | Description |
|---|---|---|
| /store/book/author | $.store.book[*].author | the authors of all books in the store |
| //author | $..author | all authors |
| /store/* | $.store.* | all things in store, which are some books and a red bicycle. |
| /store//price | $.store..price | the price of everything in the store. |
| //book[3] | $..book[2] | the third book |
| //book[last()] | $…book[(@.length-1)] $…book[-1:] |
the last book in order. |
| //book[position() < 3] | $…book[0,1] $…book[:2] |
the first two books |
| //book[isbn] | $..book[?(@.isbn)] | filter all books with isbn number |
| //book[price<10] | $…book[?(@.price<10)] | filter all books cheapier than 10 |
| //* | $..* | all Elements in XML document. All members of JSON structure. |
四、用例
使用JsonPath修改Json数据
{
"apis":[
{
"ctime":"2018-11-08 16:01:16",
"mtime":"2019-02-20 22:11:42",
"modifierId":1,
"creatorId":1,
"apiId":"1",
"authType":"none",
"version":"v3",
"path": "/test",
"httpMethod":"POST",
"serviceCode":"resource",
"cateCode":"server-task",
"mappingProtocol":"DUBBO",
"modifyVersion":1,
"onlineVersion":1,
"isOnline":"Y",
"isCached":"N",
"cachedTime":10000,
"requestMode":"MAPPING",
"servCreatorId":1134,
"requestMappingParam":{
"requestParams":[
{
"name":"tenantId",
"type":"Long",
"paramLocation":"Query",
"isRequired":true,
"defaultValue":""
},
{
"name":"userId",
"type":"Long",
"paramLocation":"Query",
"isRequired":true,
"defaultValue":""
},
{
"name":"taskId",
"type":"Long",
"paramLocation":"Query",
"isRequired":false,
"description":"ID"
},
{
"name":"taskName",
"type":"String",
"paramLocation":"Query",
"isRequired":true,
"defaultValue":"",
"description":"名称"
}
]
}
"dubboParamMappings": {
"leafParamMappings": [
{
"paramName":"tenantId",
"paramType":"java.lang.Long",
"paramMapping":"tenantId"
}
]
}
}
]
}
apis是个列表，列表包含很多map集合。
每个map代表一个api，api中包含requestParams。
其中需要将requestParams中tenantId和userId参数加上headerMapping。
"requestParams":[
{
"name":"tenantId",
"type":"Long",
"paramLocation":"Query",
"isRequired":true,
"defaultValue":"",
"headerMapping":"X-Access-TenantId" // 需要添加的东西
},
{
"name":"userId",
"type":"Long",
"paramLocation":"Query",
"isRequired":true,
"defaultValue":"",
"headerMapping":"X-Access-UserId" // 需要添加的东西
},
首先，读取json文件：
InputStream inputStream = Files.newInputStream(Paths.get("/Users/admin/Downloads/resource.json"));
构造整个文档
DocumentContext document = JsonPath.parse(inputStream);
在指定位置添加key value
- $.apis[*]是获取所有apis，这里其实只有一个。。。
- $.apis[*].requestMappingParam是获取apis列表中每个map的requestMappingParam
- $.apis[*].requestMappingParam.requestParams是获取上一步requestMappingParam中的requestParams
- [?(@.name==“tenantId”[email protected])]这个是过滤条件，指的是requestParams中包含name且等于tenantId并且requestParams没有headerMapping这个key
document.put("$.apis[*].requestMappingParam.requestParams[?(@.name==\"tenantId\"[email protected])]", "headerMapping", "X-Access-TenantId");
document.put("$.apis[*].requestMappingParam.requestParams[?(@.name==\"userId\"[email protected])]", "headerMapping", "X-Access-UserId");
- 后面两个参数分别是key和value
写入修改后的json
Files.write(Paths.get("/tmp/resource.json")), context.jsonString().getBytes());
没几行代码便完成了