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。
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