json解析神器 jsonpath的使用

轉載：http://blog.csdn.net/qq_20641565/article/details/77162868

如果項目需求是從某些復雜的json里面取值進行計算,用jsonpath+IK(ik-expression)來處理十分方便,jsonpath用來取json里面的值然后用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類里面:

下面是一個簡單的Java項目demo:

注意: 其中他的max,min,avg,stddev函數只能類似於如下處理:

//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 這里[0:2] 表示包含0 但是 不包含2 List<String> name0to2 = context.read("$.result.records[0:2].name"); //["張三","李四"] System.out.println(name0to2); //6 返回數組的最后兩個值 List<String> lastTwoName = context.read("$.result.records[-2:].name"); //["李四","王五"] System.out.println(lastTwoName); //7 返回下標為1之后的所有數組值 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 這里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里面每個對象長度 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,$.result.records[2].loan_type)"); //2.3333333333333335 System.out.println(avgV); //19 標准差 double stddevV = context.read("$.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); } }

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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; } }