在 Java 中使用 getJSONArray() 和 getJSONObject() 从 JSON 文件中获取元素

Question

我想浏览下面的json文件并保存"coordinates"之后的部分。

json 文件：

{"type": "FeatureCollection","features": [{"type": "Feature","properties": {},"geometry": {"type": "LineString","coordinates": [[4.354282,52.032195],[4.354087,52.032462],[4.353783,52.032962],[4.353579,52.033437],[4.353333,52.034151],[4.352991,52.03545],[4.352517,52.037002],[4.352442,52.037352],[4.352368,52.0378],[4.352336,52.038238],[4.352331,52.039962],[4.352346,52.040706]
    ]
  }
}

] }

我看过使用 getJSONArray() 和 getJSONObject() 的代码 here and here。这些信息帮助我 select（在我的例子中）"geometry" 树。

到目前为止我的代码（test2.geojson 是上面提到的 json 文件）：

        String output = new String(Files.readAllBytes(Paths
                .get("C:\Users\****\Desktop\test2.geojson")));

        JSONObject obj = new JSONObject(output);

        JSONArray jsonArray = obj.getJSONArray("features");
        System.out.println(jsonArray);

但是，这只会重新排列文件并将第一部分附加到文件末尾。

[{"geometry":{"coordinates":[[4.354282,52.032195],[4.354087,52.032462],[4.353783,52.032962],[4.353579,52.033437],[4.353333,52.034151],[4.352991,52.03545],[4.352517,52.037002],[4.352442,52.037352],[4.352368,52.0378],[4.352336,52.038238],[4.352331,52.039962],[4.352346,52.040706]],"type":"LineString"},"type":"Feature","properties":{}}]

获得所需输出的任何解决方案：

[[4.354282,52.032195],[4.354087,52.032462],[4.353783,52.032962],[4.353579,52.033437],[4.353333,52.034151],[4.352991,52.03545],[4.352517,52.037002],[4.352442,52.037352],[4.352368,52.0378],[4.352336,52.038238],[4.352331,52.039962],[4.352346,52.040706]
    ]
  }
}

] }

提前致谢。干杯！

Answer 1

由于"geometry"是一个json对象{}，"coordinates"是一个json数组[],

你应该做的

JSONArray jsonArray = obj.getJSONArray("features");
JSONArray resultArray = jsonArray.getJSONObject[0].getJSONObject("geometry").getJSONArray("coordinates")

在 Java 中使用 getJSONArray() 和 getJSONObject() 从 JSON 文件中获取元素

Get element from JSON file using getJSONArray() and getJSONObject() in Java

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