簡介

　　JsonPath是一種簡單的方法來提取JSON文件的方法。它支援的程式語言有很多，如java、python、JavaScript和PHP。

　　JsonPath提供的json解析非常強大，它提供了類似正則表示式的語法，基本上可以滿足所有你想要獲得的json內容。

maven依賴

<!-- https://mvnrepository.com/artifact/com.jayway.jsonpath/json-path -->
<dependency>
    <groupId>com.jayway.jsonpath</groupId>
    <
 
artifactId>json-path</artifactId>
    <version>2.6.0</version>
</dependency>

操作符

函式

函式可以在路徑的尾部呼叫，函式的輸出是路徑表示式的輸出，該函式的輸出是由函式本身所決定的

過濾操作符

過濾器是用於過濾陣列的邏輯表示式。 典型的過濾器是 [?(@.age > 18)] ，其中 @ 代表正在處理的當前專案。 可以使用邏輯運算子 && 和 || 來建立更復雜的過濾器。 字串文字必須用單引號或雙引號括起來（[?(@.color == 'blue')] 或 [?(@.color == "blue")]）。

測試的json資料

{
  "text": "張三",
  "expensive": 6,
  "body": {
    "rvNoNum": 23,
    "rvNoRecords": [{
      "score": 4,
      "rvAddress": "2",
      "consignments": null
    }, {
      "score": 8,
      "rvAddress": "3",
      "consignments": null
    }]
  }
}

測試程式碼

package jsonpathdemo;


import com.fasterxml.jackson.databind.ObjectMapper;
import com.jayway.jsonpath.JsonPath;

import java.io.IOException;
import java.util.HashMap;
import java.util.List;

public class jsonpathTest {

    public static void main(String[] args) throws IOException {

        // 定義需要測試的json字串
        String testJson = "{\n" +
                "  \"text\": \"張三\",\n" +
                "  \"expensive\": 6,\n" +
                "  \"body\": {\n" +
                "    \"rvNoNum\": 23,\n" +
                "    \"rvNoRecords\": [{\n" +
                "      \"score\": 4,\n" +
                "      \"rvAddress\": \"2\",\n" +
                "      \"consignments\": null\n" +
                "    }, {\n" +
                "      \"score\": 8,\n" +
                "      \"rvAddress\": \"3\",\n" +
                "      \"consignments\": null\n" +
                "    }]\n" +
                "  }\n" +
                "}";

        //使用jackson對字串反序列化為json物件
        ObjectMapper mapper = new ObjectMapper ( );
        HashMap responseJson = mapper.readValue ( testJson, HashMap.class );


        // 輸出text的值
        String text = JsonPath.read(responseJson,"$.text");
        System.out.println (text );

        // 輸出rvNoNum的值
        int rvNoNum = JsonPath.read(responseJson,"$.body.rvNoNum");
        System.out.println ( rvNoNum);

        //輸出rvNoRecords陣列的第2個值
        List<Object> rvNoRecords = JsonPath.read(responseJson,"$..rvNoRecords[1]");
        System.out.println ( rvNoRecords);

        //輸出rvNoRecords陣列的第1和第2個值
        List<Object> rvNoRecords1 = JsonPath.read(responseJson,"$..rvNoRecords[0,1]");
        System.out.println (rvNoRecords1 );

        //輸出rvNoRecords陣列中score<=expensive的所有值
        List<Object> rvNoRecords2 = JsonPath.read(responseJson,"$..rvNoRecords[?(@.score < $['expensive'])]");
        System.out.println ( rvNoRecords2);

        //輸出rvNoRecords[0]的rvAddress值
        String rvAddress1 = JsonPath.read(responseJson, "$.body.rvNoRecords[0].rvAddress");
        System.out.println ( rvAddress1);

        //輸出全部rvAddress的值，使用Iterator迭代
        List<String> rvAddress = JsonPath.read(responseJson,"$.body.rvNoRecords[*].rvAddress");
        System.out.println ( rvAddress);

        //輸出rvNoRecords[*]中rvAddress== '2'的rvNoRecords
        List<Object> rvAddress2 = JsonPath.read(responseJson,"$.body.rvNoRecords[?(@.rvAddress == 2)]");
        System.out.println (rvAddress2 );

        //輸出rvNoRecords[*]中score>5 的rvNoRecords
        List<Object> score = JsonPath.read(responseJson,"$.body.rvNoRecords[?(@.score>5)]");
        System.out.println ( score);

        //輸出rvNoRecords[*]中含有consignments元素的rvNoRecords
        List<Double> consignments = JsonPath.read(responseJson,"$.body.rvNoRecords[?(@.consignments)]");
        System.out.println ( consignments);

        //輸出該json中所有rvAddress的值
        List<Object> rvNoNum2 = JsonPath.read(responseJson,"$..rvAddress");
        System.out.println (rvNoNum2 );

        //輸出rvNoRecords陣列的長度
        Integer length = JsonPath.read(responseJson,"$..rvNoRecords.length()");
        System.out.println (length );

        //可以提前編輯一個路徑，並多次使用它
        JsonPath path = JsonPath.compile("$.body.rvNoRecords[*]");
        List<Object> rvNoRecords3 = path.read(responseJson);
        System.out.println (rvNoRecords3 );

    }
}

測試結果：

張三
23
[{"score":8,"rvAddress":"3","consignments":null}]
[{"score":4,"rvAddress":"2","consignments":null},{"score":8,"rvAddress":"3","consignments":null}]
[{"score":4,"rvAddress":"2","consignments":null}]
2
["2","3"]
[{"score":4,"rvAddress":"2","consignments":null}]
[{"score":8,"rvAddress":"3","consignments":null}]
[{"score":4,"rvAddress":"2","consignments":null},{"score":8,"rvAddress":"3","consignments":null}]
["2","3"]
2
[{"score":4,"rvAddress":"2","consignments":null},{"score":8,"rvAddress":"3","consignments":null}]