Question

我想将这个JSON字符串转换为可以用Java操作的对象数组。

String jsonExample = "" +
            "{&#34;c&#34;:[{&#34;v&#34;:&#34;03/10/2013&#34;},{&#34;v&#34;:23},{&#34;v&#34;:112}]},"+
            "{&#34;c&#34;:[{&#34;v&#34;:&#34;04/10/2013&#34;},{&#34;v&#34;:14},{&#34;v&#34;:232}]},"+
            "{&#34;c&#34;:[{&#34;v&#34;:&#34;05/10/2013&#34;},{&#34;v&#34;:18},{&#34;v&#34;:145}]},"+
            "{&#34;c&#34;:[{&#34;v&#34;:&#34;06/10/2013&#34;},{&#34;v&#34;:22},{&#34;v&#34;:211}]},"+
            "{&#34;c&#34;:[{&#34;v&#34;:&#34;07/10/2013&#34;},{&#34;v&#34;:18},{&#34;v&#34;:198}]},"+
            "{&#34;c&#34;:[{&#34;v&#34;:&#34;08/10/2013&#34;},{&#34;v&#34;:15},{&#34;v&#34;:215}]}";

首先，我放弃它：

String unescape = StringEscapeUtils.unescapeHtml4(jsonExample2);

然后，我尝试使用Gson，

Gson gson = new Gson();
ViewsHistoric viewHistoric = gson.fromJson(unescape, ViewsHistoric.class);

使用以下类：

    public static class ViewsHistoric {
    private List<Row> r;
    public List<Row> getR() {return r;}
    public ViewsHistoric() {}
}

public static class Row {
    private Triplet c;
    public Triplet getC() {return c;}
    public Row() {}
}

public static class Triplet {
    private String v;

    public String getV() {return v; }
    public Triplet() {}
}

但是我收到了一个错误：

java.lang.IllegalStateException：预期为BEGIN_OBJECT但在第1行第2列为STRING

嗯，实际上我在过去的几个小时里和Gson一起尝试了许多其他课程组合，但没有运气。

有人能告诉我如何将json字符串转换为java对象吗？

Answer 1

两件事：

您的JSON格式无效（即使在取消后也是如此）。
您的Triplet类是一个对象，而不是JSON数组。

我对您的代码进行了一些修改，以使其正常工作。这里有一个有效的例子

public class Q24000071 {

    public static void main(String[] args) {
             //the 'r' attribute, corresponding to 'ViewsHistoric' class, was missing
        String jsonExample = "{\"r\": ["
                + "{&#34;c&#34;:[{&#34;v&#34;:&#34;03/10/2013&#34;},{&#34;v&#34;:23},{&#34;v&#34;:112}]},"
                + "{&#34;c&#34;:[{&#34;v&#34;:&#34;04/10/2013&#34;},{&#34;v&#34;:14},{&#34;v&#34;:232}]},"
                + "{&#34;c&#34;:[{&#34;v&#34;:&#34;05/10/2013&#34;},{&#34;v&#34;:18},{&#34;v&#34;:145}]},"
                + "{&#34;c&#34;:[{&#34;v&#34;:&#34;06/10/2013&#34;},{&#34;v&#34;:22},{&#34;v&#34;:211}]},"
                + "{&#34;c&#34;:[{&#34;v&#34;:&#34;07/10/2013&#34;},{&#34;v&#34;:18},{&#34;v&#34;:198}]},"
                + "{&#34;c&#34;:[{&#34;v&#34;:&#34;08/10/2013&#34;},{&#34;v&#34;:15},{&#34;v&#34;:215}]}"
                + "]}";

        String unescape = StringEscapeUtils.unescapeHtml4(jsonExample);
        System.out.println(unescape);

        Gson gson = new GsonBuilder().setPrettyPrinting().create();
        ViewsHistoric viewHistoric = gson.fromJson(unescape,
                ViewsHistoric.class);
        System.out.println(gson.toJson(viewHistoric));
    }

    public static class ViewsHistoric {

        private List<Row> r;

        public List<Row> getR() {
            return r;
        }

        public ViewsHistoric() {
        }
    }

    public static class Row {

        // Triplet is an array in the original JSON
            // of three elements, but an array.
        private Triplet[] c;

        public Triplet[] getC() {
            return c;
        }

        public Row() {
        }
    }

    public static class Triplet {

        private String v;

        public String getV() {
            return v;
        }

        public Triplet() {
        }
    }
}

Answer 2

在对无效的实际JSON字符串进行细微更改后，只需尝试使用下面的示例代码。在这里查看JSONLint - The JSON Validator以获取JSON字符串验证。

此处结果输出为Map<String, List<Row>>，其中只有一个键r，值为Row个对象的列表。

示例代码：

Type type = new TypeToken<Map<String, List<Row>>>() {}.getType();
Map<String, List<Row>> data = new Gson().fromJson(reader, type);

System.out.println(new GsonBuilder().setPrettyPrinting().create().toJson(data));

POJO课程：

class Row {
    private List<Triplet> c;
    // getter & setter
}

class Triplet {
    private String v;
    // getter & setter
}

以漂亮的格式输出：

{
  "r": [
    {
      "c": [
        {
          "v": "03/10/2013"
        },
        {
          "v": "23"
        },
        {
          "v": "112"
        }
      ]
    },
    {
      "c": [
        {
          "v": "04/10/2013"
        },
        {
          "v": "14"
        },
        {
          "v": "232"
        }
      ]
    },
    {
      "c": [
        {
          "v": "05/10/2013"
        },
        {
          "v": "18"
        },
        {
          "v": "145"
        }
      ]
    },
    {
      "c": [
        {
          "v": "06/10/2013"
        },
        {
          "v": "22"
        },
        {
          "v": "211"
        }
      ]
    },
    {
      "c": [
        {
          "v": "07/10/2013"
        },
        {
          "v": "18"
        },
        {
          "v": "198"
        }
      ]
    },
    {
      "c": [
        {
          "v": "08/10/2013"
        },
        {
          "v": "15"
        },
        {
          "v": "215"
        }
      ]
    }
  ]
}

使用Gson创建对象数组

2 个答案: