java - Android - 使用 GSON 解析 JSON

Question

我想从 String 类型的 JSON 中解析数据。我正在使用谷歌 Gson。我想知道如何获取此 Json 字符串的“OriginalTerm”和“FirstTranslation”信息:

    {

        "term0" : {
        "PrincipalTranslations" : {
            "0" :{
                "OriginalTerm" : { "term" : "cat", "POS" : "n", "sense" : "domestic animal", "usage" : ""}, 
                "FirstTranslation" : {"term" : "gato", "POS" : "nm", "sense" : "  "}, "Note" : ""},
            "1" :{
                "OriginalTerm" : { "term" : "cat", "POS" : "n", "sense" : "member of cat family", "usage" : ""}, 
                "FirstTranslation" : {"term" : "felino", "POS" : "nm", "sense" : "familia de animales"}, "Note" : ""}},
        "AdditionalTranslations" : {
            "0" :{
                "OriginalTerm" : { "term" : "cat", "POS" : "n", "sense" : "guy", "usage" : "slang"}, 
                "FirstTranslation" : {"term" : "tío, tipo, chaval", "POS" : "nm", "sense" : "coloq"}, 
                "SecondTranslation" : {"term" : "vato", "POS" : "", "sense" : "Mex"}, "Note" : ""},

        "original" : {
        "Compounds" : {
            "0" :{
                "OriginalTerm" : { "term" : "alley cat", "POS" : "n", "sense" : "stray cat", "usage" : ""}, 
                "FirstTranslation" : {"term" : "gato callejero", "POS" : "nm", "sense" : ""}, "Note" : ""},
        "Lines" : "End Reached", "END" : true

    }     

我尝试按照这些信息进行操作，但无法解决:

http://albertattard.blogspot.com.es/2009/06/practical-example-of-gson.html

JSON parsing using Gson for Java

我尝试使用 GSON 使用 POJO 进行序列化，但我找不到正确的结构，我也尝试使用 JsonObject，跳过“term0”、“PrincipalTranslations”等对象键，但是当我有多个结果时我遇到了一些麻烦对于相同的 key ，例如:

    "0" :{
            "OriginalTerm".... 
            "FirstTranslation"...
        "1" :{
            "OriginalTerm".... 
            "FirstTranslation"...
    }

谢谢你的提前。

Answer 1

可以使用将 JSON 文本与对象一对一映射的 POJO 来使用 Gson 解析 JSON。但是，由于您只需要 JSON 字符串的一部分，您可以利用 JsonParser 对象，它允许您只获取 JSON 的一部分。

所以你可以获得 PrincipalTranslation 部分，然后应用 POJO 策略，记住你至少有两个结构:你的 Term 和两个 的组合术语 和注释(我称之为 Item)。

请记住，我编写的 POJO 不遵循 Java 命名约定，因此您可以添加 annotation使用不同的成员变量名称。

这是您可以粘贴并在您的 IDE 中运行以尝试的代码。

package stackoverflow.questions;

import java.lang.reflect.Type;
import java.util.*;

import com.google.gson.*;
import com.google.gson.reflect.TypeToken;

public class Q20337652 {

   public static class Term {
      String term;
      String POS;
      String sense;
      String usage;

      @Override
      public String toString() {
         return "Term [term=" + term + ", POS=" + POS + ", sense=" + sense + ", usage=" + usage + "]";
      }


   }

   public static class Item {
      Term OriginalTerm;
      Term FirstTranslation;
      String Note;

      @Override
      public String toString() {
         return "Item [OriginalTerm=" + OriginalTerm + ", FirstTranslation=" + FirstTranslation + ", Note=" + Note + "]";
      }


   }



   public static void main(String[] args){

          String json =                                                                                                                                 
    "  {                                                                                                                                   "+
    "                                                                                                                                      "+
    "     \"term0\" : {                                                                                                                    "+
    "     \"PrincipalTranslations\" : {                                                                                                    "+
    "         \"0\" :{                                                                                                                     "+
    "             \"OriginalTerm\" : { \"term\" : \"cat\", \"POS\" : \"n\", \"sense\" : \"domestic animal\", \"usage\" : \"\"},            "+
    "             \"FirstTranslation\" : {\"term\" : \"gato\", \"POS\" : \"nm\", \"sense\" : \"  \"}, \"Note\" : \"\"},                    "+
    "         \"1\" :{                                                                                                                     "+
    "             \"OriginalTerm\" : { \"term\" : \"cat\", \"POS\" : \"n\", \"sense\" : \"member of cat family\", \"usage\" : \"\"},       "+
    "             \"FirstTranslation\" : {\"term\" : \"felino\", \"POS\" : \"nm\", \"sense\" : \"familia de animales\"}, \"Note\" : \"\"}},"+
    "     \"AdditionalTranslations\" : {                                                                                                   "+
    "         \"0\" :{                                                                                                                     "+
    "             \"OriginalTerm\" : { \"term\" : \"cat\", \"POS\" : \"n\", \"sense\" : \"guy\", \"usage\" : \"slang\"},                   "+
    "             \"FirstTranslation\" : {\"term\" : \"tío, tipo, chaval\", \"POS\" : \"nm\", \"sense\" : \"coloq\"},                      "+
    "             \"SecondTranslation\" : {\"term\" : \"vato\", \"POS\" : \"\", \"sense\" : \"Mex\"}, \"Note\" : \"\"},                    "+
    "                                                                                                                                      "+
    "     \"original\" : {                                                                                                                 "+
    "     \"Compounds\" : {                                                                                                                "+
    "         \"0\" :{                                                                                                                     "+
    "             \"OriginalTerm\" : { \"term\" : \"alley cat\", \"POS\" : \"n\", \"sense\" : \"stray cat\", \"usage\" : \"\"},            "+
    "             \"FirstTranslation\" : {\"term\" : \"gato callejero\", \"POS\" : \"nm\", \"sense\" : \"\"}, \"Note\" : \"\"},            "+
    "     \"Lines\" : \"End Reached\", \"END\" : true                                                                                      "+
    "                                                                                                                                      "+
    " }                                                                                                                                    "+
    " }     }}}                                                                                                                               ";
      JsonParser jp = new JsonParser();
      JsonElement je = jp.parse(json);
      JsonElement je2 = je.getAsJsonObject().get("term0");
      JsonElement je3 = je2.getAsJsonObject().get("PrincipalTranslations");

      Type mapType = new TypeToken<Map<String, Item>>() {}.getType();

      Map<String, Item> principalTranslation = new Gson().fromJson(je3, mapType);

      System.out.println(principalTranslation);


   }

}

这是我的处决:

{0=Item [OriginalTerm=Term [term=cat, POS=n, sense=domestic animal, usage=], FirstTranslation=Term [term=gato, POS=nm, sense=  , usage=null], Note=], 
1=Item [OriginalTerm=Term [term=cat, POS=n, sense=member of cat family, usage=], FirstTranslation=Term [term=felino, POS=nm, sense=familia de animales, usage=null], Note=]}