Question

我正在做一个api电话，作为回应我得到了json。所以我想直接通过输入流解析它，这样就不需要将它存储在内存中。为此，我试图使用JSONReader，但我无法使用api的不到11。所以我不知道如何继续。我希望它从2.0版开始完成。即使通过JsonReader解析也无法正常工作。我是GSON解析器的东西，但我没有得到如何使用Inputstream实现相同的功能。

编辑：我的代码相同：

HttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);

try {
          HttpResponse response = client.execute(httpGet);
          StatusLine statusLine = response.getStatusLine();
          int statusCode = statusLine.getStatusCode();
          Log.e("123", "Status code ----------- "+statusCode);
          if (statusCode == 200) { 
            HttpEntity entity = response.getEntity();
            InputStream content = entity.getContent();


            // for showing it on textview i am storing in in builder
            BufferedReader bReader = new BufferedReader(new InputStreamReader(content));
            String line;
            while ((line = bReader.readLine()) != null) {
              builder.append(line);
            }

//////////// 
            JsonReader reader = new JsonReader(new InputStreamReader(content));
            reader.setLenient(true);
            readGson(reader);
          } else {
            Log.e("TAG", "Failed to download file");
          }
        } catch (ClientProtocolException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        }
        return builder.toString();
      }

private void readGson(JsonReader reader) {
    // TODO Auto-generated method stub
    Log.e("TAG", "inidde readgson"+reader);

                 try {
                     Log.e("TAG", "inside try");
                    reader.beginObject();
                    Log.e("123", "inside try  ");
                     while(reader.hasNext()){
                         Log.e("TAG", "reader values"+reader);
                         String name = reader.nextName();
                         if (name.equals("max_id")) {
                             long max_id = reader.nextLong();
                             Log.e("TAG", "sdbfhsajfgsdjbgksdfjv------------------"+max_id);
                           }  else {
                               Log.e("TAG", "c skfnvklsfvn skip value");
                             reader.skipValue();
                           }
                     }
                     reader.endObject();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    Log.e("TAG", "inside catch");
                    e.printStackTrace();
                }
}

输出：

    01-28 10:20:53.519: E/TAG(420): Status code ----------- 200
01-28 10:20:53.679: E/TAG(420): inidde readgsonJsonReader at line 1 column 1
01-28 10:20:53.679: E/TAG(420): inside try
01-28 10:20:53.679: E/TAG(420): inside catch
01-28 10:20:53.679: W/System.err(420): java.io.EOFException: End of input at line 1 column 1
01-28 10:20:53.689: W/System.err(420):  at com.google.gson.stream.JsonReader.nextNonWhitespace(JsonReader.java:954)
01-28 10:20:53.689: W/System.err(420):  at com.google.gson.stream.JsonReader.consumeNonExecutePrefix(JsonReader.java:405)
01-28 10:20:53.689: W/System.err(420):  at com.google.gson.stream.JsonReader.peek(JsonReader.java:364)
01-28 10:20:53.689: W/System.err(420):  at com.google.gson.stream.JsonReader.expect(JsonReader.java:337)
01-28 10:20:53.689: W/System.err(420):  at com.google.gson.stream.JsonReader.beginObject(JsonReader.java:322)
01-28 10:20:53.689: W/System.err(420):  at com.example.httpconnectiondemo.MainActivity.readGson(MainActivity.java:136)
01-28 10:20:53.699: W/System.err(420):  at com.example.httpconnectiondemo.MainActivity.readTwitterFeed(MainActivity.java:116)
01-28 10:20:53.699: W/System.err(420):  at com.example.httpconnectiondemo.MainActivity.onCreate(MainActivity.java:64)
01-28 10:20:53.699: W/System.err(420):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-28 10:20:53.699: W/System.err(420):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
01-28 10:20:53.699: W/System.err(420):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
01-28 10:20:53.699: W/System.err(420):  at android.app.ActivityThread.access$1500(ActivityThread.java:117)
01-28 10:20:53.699: W/System.err(420):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
01-28 10:20:53.699: W/System.err(420):  at android.os.Handler.dispatchMessage(Handler.java:99)
01-28 10:20:53.699: W/System.err(420):  at android.os.Looper.loop(Looper.java:123)
01-28 10:20:53.699: W/System.err(420):  at android.app.ActivityThread.main(ActivityThread.java:3683)
01-28 10:20:53.710: W/System.err(420):  at java.lang.reflect.Method.invokeNative(Native Method)
01-28 10:20:53.710: W/System.err(420):  at java.lang.reflect.Method.invoke(Method.java:507)
01-28 10:20:53.710: W/System.err(420):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
01-28 10:20:53.710: W/System.err(420):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
01-28 10:20:53.710: W/System.err(420):  at dalvik.system.NativeStart.main(Native Method)

提前致谢。

Answer 1

您以错误的方式使用content信息流。看看标记的行：

InputStream content = entity.getContent();

// (1)
BufferedReader bReader = new BufferedReader(new InputStreamReader(content));
String line;
while ((line = bReader.readLine()) != null) {
    builder.append(line);
}

// (2)
JsonReader reader = new JsonReader(new InputStreamReader(content));
reader.setLenient(true);
readGson(reader);

这里的问题是你将相同的流包裹两次（在标记的行上）。

在第一次换行之后，您将通过收集行的流并在builder中连接它们。您必须意识到有效bReader只是content流的包装器。因此，当您收集行时，将使用content流中的内容。因此，当(line = ...) != null流在输入结束时，条件false为content。
然后再次包装content流 - 用于解析JSON内容。但是流已经在输入的末尾，因此JSON阅读器没有任何消耗。这正是行的意思：java.io.EOFException: End of input at line 1 column 1你的例外。

您需要做的只是阅读content流一次。所以，你有几个选择：

请勿将收到的内容保存到String。您删除第一个包装和使用builder构建响应字符串的循环。如果这不是一个选项，那么我建议：

将整个回复保存到String。注意：您可以使用EntityUtils类，因为它可以为您完成工作：

HttpEntity entity = response.getEntity();

// All the work is done for you here :)
String jsonContent = EntityUtils.toString(entity);

// Create a Reader from String
Reader stringReader = new StringReader(jsonContent);

// Pass the string reader to JsonReader constructor
JsonReader reader = new JsonReader(stringReader);
reader.setLenient(true);
readGson(reader);

...
// at the end of method return the JSON response
return jsonContent;

使用输入流直接解析json

1 个答案: