基於json解析神器 jsonpath的使用說明

如果項目需求是從某些復雜的json裡面取值進行計算,用jsonpath+IK(ik-expression)來處理十分方便,jsonpath用來取json裡面的值然後用IK自帶的函數進行計算,如果是特殊的計算那就自定義IK方法搞定,配置化很方便.

下面簡單介紹下jsonpath的使用方法,主要測試都在JsonPathDemo類裡面:

下面是一個簡單的java項目demo:

註意: 其中他的max,min,avg,stddev函數隻能類似於如下處理:

//正確寫法 但是感覺很雞肋
context.read("$.avg($.result.records[0].loan_type,$.result.records[1].loan_type,$.result.records[2].loan_type)");

不能傳入list 感覺比較雞肋,如果傳入list 他會報錯(如下錯誤寫法):

//這樣會報錯
Object maxV = context.read("$.max($.result.records[*].loan_type)");
//這樣也會報錯
Object maxV = context.read("$.result.records[*].loan_type.max()");
//如果json文件中是這樣:"loan_type":"2",也會報錯,"loan_type":2 這樣才被認為是數字

報錯信息都一樣, 如下:

Exception in thread “main” com.jayway.jsonpath.JsonPathException: Aggregation function attempted to calculate value using empty array

JsonPathDemo是一個測試demo:

public class JsonPathDemo {
 public static void main(String[] args) {
 String json = FileUtils.readFileByLines("demo.json");
 ReadContext context = JsonPath.parse(json);
 //1 返回所有name
 List<String> names = context.read("$.result.records[*].name");
 //["張三","李四","王五"]
 System.out.println(names);
 //2 返回所有數組的值
 List<Map<String, String>> objs = context.read("$.result.records[*]");
 //[{"name":"張三","pid":"500234199212121212","mobile":"18623456789","applied_at":"3","confirmed_at":"5","confirm_type":"overdue","loan_type":"1","test":"mytest","all":"2"},{"name":"李四","pid":"500234199299999999","mobile":"13098765432","applied_at":"1","confirmed_at":"","confirm_type":"overdue","loan_type":"3","all":"3"},{"name":"王五","pid":"50023415464654659","mobile":"1706454894","applied_at":"-1","confirmed_at":"","confirm_type":"overdue","loan_type":"3"}]
 System.out.println(objs);
 //3 返回第一個的name
 String name0 = context.read("$.result.records[0].name");
 //張三
 System.out.println(name0);
 //4 返回下標為0 和 2 的數組值
 List<String> name0and2 = context.read("$.result.records[0,2].name");
 //["張三","王五"]
 System.out.println(name0and2);
 //5 返回下標為0 到 下標為1的 的數組值 這裡[0:2] 表示包含0 但是 不包含2
 List<String> name0to2 = context.read("$.result.records[0:2].name");
 //["張三","李四"]
 System.out.println(name0to2);
 //6 返回數組的最後兩個值
 List<String> lastTwoName = context.read("$.result.records[-2:].name");
 //["李四","王五"]
 System.out.println(lastTwoName);
 //7 返回下標為1之後的所有數組值 包含下標為1的
 List<String> nameFromOne = context.read("$.result.records[1:].name");
 //["李四","王五"]
 System.out.println(nameFromOne);
 //8 返回下標為3之前的所有數組值 不包含下標為3的
 List<String> nameEndTwo = context.read("$.result.records[:3].name");
 //["張三","李四","王五"]
 System.out.println(nameEndTwo);
 //9 返回applied_at大於等於2的值
 List<Map<String, String>> records = context.read("$.result.records[?(@.applied_at >= '2')]");
 //[{"name":"張三","pid":"500234199212121212","mobile":"18623456789","applied_at":"3","confirmed_at":"5","confirm_type":"overdue","loan_type":"1","test":"mytest","all":"2"}]
 System.out.println(records);
 //10 返回name等於李四的值
 List<Map<String, String>> records0 = context.read("$.result.records[?(@.name == '李四')]");
 //[{"name":"李四","pid":"500234199299999999","mobile":"13098765432","applied_at":"1","confirmed_at":"","confirm_type":"overdue","loan_type":"3"}]
 System.out.println(records0);
 //11 返回有test屬性的數組
 List<Map<String, String>> records1 = context.read("$.result.records[?(@.test)]");
 //[{"name":"張三","pid":"500234199212121212","mobile":"18623456789","applied_at":"3","confirmed_at":"5","confirm_type":"overdue","loan_type":"1","test":"mytest","all":"2"}]
 System.out.println(records1);
 //12 返回有test屬性的數組
 List<String> list = context.read("$..all");
 //["1","4","2","3"]
 System.out.println(list);
 //12 以當前json的某個值為條件查詢 這裡ok為1 取出records數組中applied_at等於1的數組
 List<String> ok = context.read("$.result.records[?(@.applied_at == $['ok'])]");
 //["1","4","2","3"]
 System.out.println(ok);
 //13 正則匹配
 List<String> regexName = context.read("$.result.records[?(@.pid =~ /.*999/i)]");
 //[{"name":"李四","pid":"500234199299999999","mobile":"13098765432","applied_at":"1","confirmed_at":"","confirm_type":"overdue","loan_type":"3","all":"3"}]
 System.out.println(regexName);
 //14 多條件
 List<String> mobile = context.read("$.result.records[?(@.all == '2' || @.name == '李四' )].mobile");
 //["18623456789","13098765432"]
 System.out.println(mobile);
 //14 查詢數組長度
 Integer length01 = context.read("$.result.records.length()");
 //3
 System.out.println(length01);
 //15 查詢list裡面每個對象長度
 List<Integer> length02 = context.read("$.result.records[?(@.all == '2' || @.name == '李四' )].length()");
 //[9,8]
 System.out.println(length02);
 //16 最大值
 Object maxV = context.read("$.max($.result.records[0].loan_type,$.result.records[1].loan_type,$.result.records[2].loan_type)");
 //3.0
 System.out.println(maxV);
 //17 最小值
 Object minV = context.read("$.min($.result.records[0].loan_type,$.result.records[1].loan_type,$.result.records[2].loan_type)");
 //1.0
 System.out.println(minV);
 //18 平均值
 double avgV = context.read("$.avg($.result.records[0].loan_type,$.result.records[1].loan_type,$.result.records[2].loan_type)");
 //2.3333333333333335
 System.out.println(avgV);
 //19 標準差
 double stddevV = context.read("$.stddev($.result.records[0].loan_type,$.result.records[1].loan_type,$.result.records[2].loan_type)");
 //0.9428090415820636
 System.out.println(stddevV);
 //20 讀取一個不存在的
 String haha = context.read("$.result.haha");
 //拋出異常
 //Exception in thread "main" com.jayway.jsonpath.PathNotFoundException: No results for path: $['result']['haha']
 //at com.jayway.jsonpath.internal.path.EvaluationContextImpl.getValue(EvaluationContextImpl.java:133)
 //at com.jayway.jsonpath.JsonPath.read(JsonPath.java:187)
 //at com.jayway.jsonpath.internal.JsonContext.read(JsonContext.java:102)
 //at com.jayway.jsonpath.internal.JsonContext.read(JsonContext.java:89)
 //at cn.lijie.jsonpath.JsonPathDemo.main(JsonPathDemo.java:58)
 //at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 //at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 //at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 //at java.lang.reflect.Method.invoke(Method.java:498)
 //at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
 System.out.println(haha);
 }
}

pom文件引入:

 <dependency>
  <groupId>com.jayway.jsonpath</groupId>
  <artifactId>json-path</artifactId>
  <version>2.3.0</version>
 </dependency>

其中demo.json是一個測試json:

{
 "action": "/interface.service/xxx/queryBlackUserData",
 "all": "1",
 "result": {
 "count": 2,
 "tenant_count": 2,
 "records": [
 {
 "name": "張三",
 "pid": "500234199212121212",
 "mobile": "18623456789",
 "applied_at": "3",
 "confirmed_at": "5",
 "confirm_type": "overdue",
 "loan_type": 1,
 "test": "mytest",
 "all": "2"
 },
 {
 "name": "李四",
 "pid": "500234199299999999",
 "mobile": "13098765432",
 "applied_at": "1",
 "confirmed_at": "",
 "confirm_type": "overdue",
 "loan_type": 3,
 "all": "3"
 },
 {
 "name": "王五",
 "pid": "50023415464654659",
 "mobile": "1706454894",
 "applied_at": "-1",
 "confirmed_at": "",
 "confirm_type": "overdue",
 "loan_type": 3
 }
 ],
 "all": "4"
 },
 "code": 200,
 "subtime": "1480495123550",
 "status": "success",
 "ok": 3
}

FileUtils類是用於讀取xx.json文件為字符串的json:

public class FileUtils {
 /**
 * 以行為單位讀取文件,常用於讀面向行的格式化文件
 */
 public static String readFileByLines(String fileName) {
 File file = new File(fileName);
 BufferedReader reader = null;
 String str = "";
 try {
  InputStream is = FileUtils.class.getClassLoader().getResourceAsStream(fileName);
  reader = new BufferedReader(new InputStreamReader(is));
  String tempString = null;
  int line = 1;
  // 一次讀入一行,直到讀入null為文件結束
  while ((tempString = reader.readLine()) != null) {
  // 顯示行號
  str += tempString;
  }
  reader.close();
 } catch (IOException e) {
  e.printStackTrace();
 } finally {
  if (reader != null) {
  try {
   reader.close();
  } catch (IOException e1) {
  }
  }
 }
 return str;
 }
}

補充:json接口測試的利器jsonpath

在測試REST接口的時候,經常要解析JSON,那麼可以使用開源jsonpath進行,其中看網上看到相關的說法不錯的使用場景為:

1、接口關聯

也稱為關聯參數。在應用業務接口中,完成一個業務功能時,有時候一個接口可能不滿足業務的整個流程邏輯,需要多個接口配合使用,簡單的案例如:B接口的成功調用依賴於A接口,需要在A接口的響應數據(response)中拿到需要的字段,在調用B接口的時候,傳遞給B接口作為B接口請求參數,拿到後續響應的響應數據。

接口關聯通常可以使用正則表達式去提取需要的數據,但對於json這種簡潔、清晰層次結構、輕量級的數據交互格式,使用正則未免有點殺雞用牛刀的感覺(是的,因為我不擅長寫正則表達式),我們需要更加簡單、直接的提取json數據的方式。

2、數據驗證

這裡的數據驗證指的是對響應結果進行數據的校驗

接口自動化測試中,對於簡單的響應結果(json),可以直接和期望結果進行比對,判斷是否完全相等即可。

如 json {“status”:1,”msg”:”登錄成功”}

3、對於格式較復雜

尤其部分數據存在不確定性、會根據實際情況變化的響應結果,簡單的判斷是否完全相等(斷言)通常會失敗。

如:

json {"status":1,"code":"10001","data":[{"id":1,"investId":"1","createTime":"2018-04-27 12:24:01","terms":"1","unfinishedInterest":"1.0","unfinishedPrincipal":"0","repaymentDate":"2018-05-27 12:24:01","actualRepaymentDate":null,"status":"0"},{"id":2,"investId":"1","createTime":"2018-04-27 12:24:01","terms":"2","unfinishedInterest":"1.0","unfinishedPrincipal":"0","repaymentDate":"2018-06-27 12:24:01","actualRepaymentDate":null,"status":"0"},{"id":3,"investId":"1","createTime":"2018-04-27 12:24:01","terms":"3","unfinishedInterest":"1.0","unfinishedPrincipal":"100.00","repaymentDate":"2018-07-27 12:24:01","actualRepaymentDate":null,"status":"0"}],"msg":"獲取信息成功"}

上面的json結構嵌套瞭很多信息,完整的匹配幾乎不可能成功。比如其中的createTime信息,根據執行接口測試用例的時間每次都不一樣。同時這個時間是響應結果中較為次要的信息,在進行接口自動化測試時,是可以選擇被忽略的。

4、我們需要某種簡單的方法

能夠從json中提取出我們真正關註的信息(通常也被稱為關鍵信息)。

如提取出status的值為1,data數組中每個對象的investId都為1,data中第三個對象的unfinishedPrincipal值為100.00,隻要這三個關鍵信息校驗通過,我們就認為響應結果沒有問題。

JSONPATH有點像XPATH瞭,語法規則小結下:

這裡有個表格,說明JSONPath語法元素和對應XPath元素的對比。

XPath JSONPath Description
/ $ 表示根元素
. @ 當前元素
/ . or [] 子元素
.. n/a 父元素
// .. 遞歸下降,JSONPath是從E4X借鑒的。
* * 通配符,表示所有的元素
@ n/a 屬性訪問字符
[] []

子元素操作符

| [,]

連接操作符在XPath 結果合並其它結點集合。JSONP允許name或者數組索引。

n/a [start:end:step]

數組分割操作從ES4借鑒。

[] ?()

應用過濾表示式

n/a ()

腳本表達式,使用在腳本引擎下面。

() n/a Xpath分組

下面是一個簡單的json數據結構代表一個書店(原始的xml文件是)

{ "store": {
 "book": [ 
 { "category": "reference",
 "author": "Nigel Rees",
 "title": "Sayings of the Century",
 "price": 8.95
 },
 { "category": "fiction",
 "author": "Evelyn Waugh",
 "title": "Sword of Honour",
 "price": 12.99
 },
 { "category": "fiction",
 "author": "Herman Melville",
 "title": "Moby Dick",
 "isbn": "0-553-21311-3",
 "price": 8.99
 },
 { "category": "fiction",
 "author": "J. R. R. Tolkien",
 "title": "The Lord of the Rings",
 "isbn": "0-395-19395-8",
 "price": 22.99
 }
 ],
 "bicycle": {
 "color": "red",
 "price": 19.95
 }
 }
}
XPath JSONPath 結果
/store/book/author $.store.book[*].author

書點所有書的作者

//author $..author

所有的作者

/store/* $.store.*

store的所有元素。所有的bookst和bicycle

/store//price $.store..price

store裡面所有東西的price

//book[3] $..book[2]

第三個書

//book[last()] $..book[(@.length-1)] 最後一本書
//book[position()<3] $..book[0,1]

$..book[:2]

前面的兩本書。
//book[isbn] $..book[?(@.isbn)] 過濾出所有的包含isbn的書。
//book[price<10] $..book[?(@.price<10)] 過濾出價格低於10的書。
//* $..*

所有元素。

比如在單元測試MOCK中,就可以這樣使用:

@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureMockMvc
@ActiveProfiles("test")
public class BookControllerTest { 
 @Autowired
 private MockMvc mockMvc; 
 @MockBean
 private BookRepository mockRepository; 
 /*
 {
  "timestamp":"2019-03-05T09:34:13.280+0000",
  "status":400,
  "errors":["Author is not allowed.","Please provide a price","Please provide a author"]
 }
 */
 //article : jsonpath in array
 @Test
 public void save_emptyAuthor_emptyPrice_400() throws Exception {
 
 String bookInJson = "{\"name\":\"ABC\"}"; 
 mockMvc.perform(post("/books")
  .content(bookInJson)
  .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON))
  .andDo(print())
  .andExpect(status().isBadRequest())
  .andExpect(jsonPath("$.timestamp", is(notNullValue())))
  .andExpect(jsonPath("$.status", is(400)))
  .andExpect(jsonPath("$.errors").isArray())
  .andExpect(jsonPath("$.errors", hasSize(3)))
  .andExpect(jsonPath("$.errors", hasItem("Author is not allowed.")))
  .andExpect(jsonPath("$.errors", hasItem("Please provide a author")))
  .andExpect(jsonPath("$.errors", hasItem("Please provide a price")));
 
 verify(mockRepository, times(0)).save(any(Book.class));
 
 }
}

以上為個人經驗,希望能給大傢一個參考,也希望大傢多多支持WalkonNet。如有錯誤或未考慮完全的地方,望不吝賜教。