如何避免 GSON JsonObject 中的反斜杠？

Question

我有一个 Java POJO

public class TagBean {
  private String type;
  private String id;

  public TagBean(String type, String id) {
    this.type = type;
    this.id = id;       
  }
    // getters
    // setters   
}

我正在构建 pojo 并将它们添加到列表中，如

....
List<TagBean> channelsList = new ArrayList<>();
List<TagBean> showsList = new ArrayList<>();
for each <business logic> {
   if value=channels {
      channelsList.add(new TagBean(...));
   }
   if value=shows {
      showsList.add(new TagBean(...));
   }
}

Gson gson = new GsonBuilder().create();
JsonObject tjsonObject = new JsonObject();
tjsonObject.addProperty("channels", gson.toJson(channelsList));
tjsonObject.addProperty("shows", gson.toJson(showsList));

JsonObject mainjsonObject = mainjsonObject.add("tags", tjsonObject);

return mainjsonObject;

我的输出是：

{
"tags": {
    "channels": "[{\"type\":\"channel\",\"id\":\"channel\",\"name\":\"Channel\",\"parent\":\"SXM\"}]",
    "shows": "[{\"type\":\"shows\",\"id\":\"shows\",\"name\":\"Shows\",\"parent\":\"SXM\"},{\"type\":\"shows\",\"id\":\"howard\",\"name\":\"Howard Stern\",\"parent\":\"shows\"},{\"type\":\"shows\",\"id\":\"howardstern\",\"name\":\"Howard Stern\",\"parent\":\"howard\"}]",
    "sports": "[]"
}
}

如何删除反斜杠？所以输出是这样的：

{
  "tags": {
     "channels": " [{"type":"channel","id":"channel","name":"Channel","parent":"SXM"}]",
    "shows": "[{"type":"shows","id":"shows","name":"Shows","parent":"SXM"},{"type":"shows","id":"howard","name":"Howard Stern","parent":"shows"}....

其他帖子很少，但没有一个解释这一点。

Answer 1

问题是这样引起的：

tjsonObject.addProperty("channels", gson.toJson(channelsList));

其作用是转换channelsList为包含 JSON 列表表示形式的字符串，然后将属性设置为该字符串。由于字符串包含 JSON 元字符，因此在字符串第二次序列化时必须对它们进行转义。

我认为你需要这样做：

tjsonObject.add("channels", gson.toJsonTree(channelsList));

这应该会产生这样的结果：

{
  "tags": {
     "channels":     
        [{"type":"channel","id":"channel","name":"Channel","parent":"SXM"}],
     "shows": 
        [{"type":"shows","id":"shows","name":"Shows","parent":"SXM"},
         {"type":"shows","id":"howard","name":"Howard Stern","parent":"shows"}
   ....

这与您的问题要求的略有不同，但它的优点是语法上有效的 JSON！