java - 如何用Gson解析响应

Question

我有一个 Android 应用程序，该应用程序可以联系 Web 服务，通过 JSON 进行响应，并发送一个对象。我想使用 Gson 库来转换 Object.所以我有这个方法但不起作用。

      private static Impresa getDatiImpresa(String url) throws 
        IOException, MalformedURLException, JSONException
        {
            String result = "";
            Gson gson = new Gson();
            HttpClient client = new DefaultHttpClient();
            HttpConnectionParams.setConnectionTimeout(client.getParams(), 10000); //Timeout Limit
            HttpResponse response;
            try {
                HttpPost post = new HttpPost(url);
                response = client.execute(post);

                /*Checking response */
                if(response!=null){

                    InputStream source = response.getEntity().getContent(); //Get the data in the entity
                    Reader reader = new InputStreamReader(source);
                    Impresa impresa = gson.fromJson(reader, Impresa.class);
                   return impresa;
                }

            } catch(Exception e) {
                e.printStackTrace();
                //createDialog("Error", "Cannot Estabilish Connection");
            }
            return null;
        }

public class Impresa {
    @SerializedName("pivaImpresa")
    public String partitaIVA;
    @SerializedName("ragioneSociale")
    public String ragioneSociale;
    @SerializedName("centriAziendali")
    public List<CentroAziendale> listaCentroAziendale;

    public String getPartitaIVA() {
        return partitaIVA;
    }
    public void setPartitaIVA(String partitaIVA) {
        this.partitaIVA = partitaIVA;
    }
    public String getRagioneSociale() {
        return ragioneSociale;
    }
    public void setRagioneSociale(String ragioneSociale) {
        this.ragioneSociale = ragioneSociale;
    }
    public List<CentroAziendale> getListaCentroAziendale() {
        return listaCentroAziendale;
    }
    public void setListaCentroAziendale(List<CentroAziendale> listaCentroAziendale) {
        this.listaCentroAziendale = listaCentroAziendale;
    }
}

该方法每次都返回 null。

我使用此代码来读取网络服务的响应。这是代码:

StringBuilder sb = new StringBuilder();
BufferedReader r = new BufferedReader(new InputStreamReader(new DoneHandlerInputStream(source)));
for (String line = r.readLine(); line != null; line = r.readLine()){
   sb.append(line);
}

这是网络服务的响应:

{"status":1,"message":"Ok","content":[{"pivaImpresa":"05050505055","ragioneSociale":"Azienda Giustina","centriAziendali":[{"pivaImpresa":"05050505055","codiceCentroAziendale":"C001"}]}]}

Answer 1

如果反序列化的 JSON 与包含所有必填字段的类定义不同，Gson 将返回 null。

因此，您需要将类定义为与 JSON 相同:

public class JsonResponse {
   private int status;
   private String message;
   private List<Impresa> content;
}

定义 setter 就这样了。反序列化时使用

JsonResponse json = gson.fromJson(reader, JsonResponse.class);