android - 改造 - 在将其解析为 json 之前从响应主体中删除一些无效字符

Question

我有一个外部 Web 服务，它在响应正文中返回 json 但嵌套在括号中，如下所示:

({"door_x":"103994.001461","door_y":"98780.7862376", "distance":"53.3"})

使用这段代码:

class AddressInfo {
    String door_x;
    String door_y;
}

interface AddressWebService {
    @GET("/reversegeocoding")
    AddressInfo reverseGeocoding(@Query("x") double x, @Query("y") double y);
}

显然失败了。这是堆栈跟踪:

retrofit.RetrofitError: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1
        at retrofit.RestAdapter$RestHandler.invokeRequest(RestAdapter.java:377)
        at retrofit.RestAdapter$RestHandler.invoke(RestAdapter.java:240)
        at com.something.$Proxy7.reverseGeocoding(Native Method)
        at com.something.ReverseGeocodingService.getAddress(ReverseGeocodingService.java:24)
        at com.something.LocationProvider$1.run(LocationProvider.java:77)
        at java.lang.Thread.run(Thread.java:864)
 Caused by: retrofit.converter.ConversionException: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1
        at retrofit.converter.GsonConverter.fromBody(GsonConverter.java:67)
        at retrofit.RestAdapter$RestHandler.invokeRequest(RestAdapter.java:362)
            at retrofit.RestAdapter$RestHandler.invoke(RestAdapter.java:240)
            at com.something.$Proxy7.reverseGeocoding(Native Method)
            at com.something.ReverseGeocodingService.getAddress(ReverseGeocodingService.java:24)
            at com.something.LocationProvider$1.run(LocationProvider.java:77)
            at java.lang.Thread.run(Thread.java:864)
 Caused by: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:176)
        at com.google.gson.Gson.fromJson(Gson.java:803)
        at com.google.gson.Gson.fromJson(Gson.java:768)
        at retrofit.converter.GsonConverter.fromBody(GsonConverter.java:63)
            at retrofit.RestAdapter$RestHandler.invokeRequest(RestAdapter.java:362)
            at retrofit.RestAdapter$RestHandler.invoke(RestAdapter.java:240)
            at com.something.$Proxy7.reverseGeocoding(Native Method)
            at com.something.ReverseGeocodingService.getAddress(ReverseGeocodingService.java:24)
            at com.something.LocationProvider$1.run(LocationProvider.java:77)
            at java.lang.Thread.run(Thread.java:864)
 Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1
        at com.google.gson.stream.JsonReader.beginObject(JsonReader.java:374)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:165)
            at com.google.gson.Gson.fromJson(Gson.java:803)
            at com.google.gson.Gson.fromJson(Gson.java:768)
            at retrofit.converter.GsonConverter.fromBody(GsonConverter.java:63)
            at retrofit.RestAdapter$RestHandler.invokeRequest(RestAdapter.java:362)
            at retrofit.RestAdapter$RestHandler.invoke(RestAdapter.java:240)
            at com.something.$Proxy7.reverseGeocoding(Native Method)
            at com.something.ReverseGeocodingService.getAddress(ReverseGeocodingService.java:24)
            at com.something.LocationProvider$1.run(LocationProvider.java:77)
            at java.lang.Thread.run(Thread.java:864)

在解析 json 之前删除括号的最佳方法是什么？

Answer 1

在 Gson 将正文反序列化为类型对象之前，您可以轻松清除 GsonConverter 中的响应。

 public class CleanGsonConverter extends GsonConverter{

            public CleanGsonConverter(Gson gson) {
                super(gson);
            }

            public CleanGsonConverter(Gson gson, String encoding) {
                super(gson, encoding);
            }

            @Override
            public Object fromBody(TypedInput body, Type type) throws ConversionException {
                String dirty = toString(body);
                String clean = dirty.replaceAll("(^\\(|\\)$)", "");
                body = new JsonTypedInput(clean.getBytes(Charset.forName(HTTP.UTF_8)));
                return super.fromBody(body, type);
            }
            private String toString(TypedInput body){
                    BufferedReader br = null;
                    StringBuilder sb = new StringBuilder();
                    String line;
                    try {
                        br = new BufferedReader(new InputStreamReader(body.in()));
                        while ((line = br.readLine()) != null) {
                            sb.append(line);
                        }

                    } catch (IOException e) {
                        e.printStackTrace();
                    } finally {
                        if (br != null) {
                            try {
                                br.close();
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    }

                    return sb.toString();

                }
        };

JsonTypedInput:

   public class JsonTypedInput implements TypedInput{

        private final byte[] mStringBytes;

        JsonTypedInput(byte[] stringBytes) {
            this.mStringBytes = stringBytes;
        }


        @Override
        public String mimeType() {
            return "application/json; charset=UTF-8";
        }



        @Override
        public long length() {
            return mStringBytes.length;
        }

        @Override
        public InputStream in() throws IOException {
            return new ByteArrayInputStream(mStringBytes);
        }
    }

在这里，我将 GsonConverter 子类化，以便在将响应转换为对象之前访问它。 JsonTypedOutput 用于在清除垃圾字符后保留响应的 mime 类型。

用法:

restAdapterBuilder.setConverter(new CleanGsonConverter(gson));

这要归咎于您的后端人员。 :)