gson.fromJson()中的内存不足异常

Question

我使用以下代码将Json字符串(strWebserviceResult)转换为我的Object:

EntMyClass entMyClass = gson.fromJson(strWebserviceResult,EntMyClass.class);

当strWebserviceResult很大(大约2.5 MB)时,我在Android手机设备上的这条线路上出现内存不足异常,而不是内存较大的平板电脑.

我怎么解决这个问题.

有人有什么建议吗？

05-26 15:52:49.607: E/dalvikvm-heap(2078): Out of memory on a 9200-byte allocation.
05-26 15:52:49.618: E/dalvikvm(2078): Out of memory: Heap Size=31879KB, Allocated=27693KB, Bitmap Size=936KB, Limit=32768KB
05-26 15:52:49.618: E/dalvikvm(2078): Extra info: Footprint=31879KB, Allowed Footprint=31879KB, Trimmed=7400KB
05-26 15:52:49.618: E/AndroidRuntime(2078): FATAL EXCEPTION: Thread-19
05-26 15:52:49.618: E/AndroidRuntime(2078): java.lang.OutOfMemoryError: (Heap Size=31879KB, Allocated=27693KB, Bitmap Size=936KB)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at java.util.ArrayList.add(ArrayList.java:123)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.DefaultTypeAdapters$CollectionTypeAdapter.deserialize(DefaultTypeAdapters.java:664)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.DefaultTypeAdapters$CollectionTypeAdapter.deserialize(DefaultTypeAdapters.java:624)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonDeserializerExceptionWrapper.deserialize(JsonDeserializerExceptionWrapper.java:51)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonDeserializationVisitor.invokeCustomDeserializer(JsonDeserializationVisitor.java:92)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonObjectDeserializationVisitor.visitFieldUsingCustomHandler(JsonObjectDeserializationVisitor.java:117)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.ReflectingFieldNavigator.visitFieldsReflectively(ReflectingFieldNavigator.java:63)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.ObjectNavigator.accept(ObjectNavigator.java:120)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonDeserializationContextDefault.fromJsonObject(JsonDeserializationContextDefault.java:76)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonDeserializationContextDefault.deserialize(JsonDeserializationContextDefault.java:54)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.DefaultTypeAdapters$CollectionTypeAdapter.deserialize(DefaultTypeAdapters.java:663)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.DefaultTypeAdapters$CollectionTypeAdapter.deserialize(DefaultTypeAdapters.java:624)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonDeserializerExceptionWrapper.deserialize(JsonDeserializerExceptionWrapper.java:51)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonDeserializationVisitor.invokeCustomDeserializer(JsonDeserializationVisitor.java:92)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonDeserializationVisitor.visitUsingCustomHandler(JsonDeserializationVisitor.java:80)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.ObjectNavigator.accept(ObjectNavigator.java:101)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonDeserializationContextDefault.fromJsonArray(JsonDeserializationContextDefault.java:67)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.JsonDeserializationContextDefault.deserialize(JsonDeserializationContextDefault.java:52)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.Gson.fromJson(Gson.java:551)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.Gson.fromJson(Gson.java:498)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.Gson.fromJson(Gson.java:467)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.Gson.fromJson(Gson.java:417)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at com.google.gson.Gson.fromJson(Gson.java:389)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at org.mabna.order.businessLayer.BoWebService.getDataForUpdate(BoWebService.java:188)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at org.mabna.order.ui.ActToolDataExchange.threadGetDataForFullUpdate(ActToolDataExchange.java:371)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at org.mabna.order.ui.ActToolDataExchange.access$9(ActToolDataExchange.java:362)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at org.mabna.order.ui.ActToolDataExchange$33.run(ActToolDataExchange.java:603)
05-26 15:52:49.618: E/AndroidRuntime(2078):     at org.mabna.order.utils.Utilities$5.run(Utilities.java:778)

Answer 1

尝试使用将JsonReader作为输入的fromJson方法.这应该允许您不需要整个输入字符串一次在内存中.这是一些示例代码:

        final HttpURLConnection c = (HttpURLConnection) url.openConnection();
        final InputStreamReader isr = new InputStreamReader(c.getInputStream());
        final JsonReader reader = new JsonReader(isr);
        final EntMyClass entMyClass = GSON.fromJson(reader, EntMyClass.class);
        reader.close();
        c.disconnect();

Answer 2

与其他帖子一样,我会问是否有任何方法可以避免您的应用程序使用大量内存.如果你能做到这一点,它将是最理想的解决方案.如果您的应用确实需要那么多内存,您可以尝试android:largeHeap="true"在清单中设置应用程序.这是参考:

http://developer.android.com/reference/android/R.styleable.html#AndroidManifestApplication_largeHeap

有关更多信息,请参阅此视频:

http://www.youtube.com/watch?v=_CruQY55HOk