如何將Httpclient的響應object序列化和反序列化為字節數組

Question

我想對Apache、okhttp客戶端等的http響應object進行序列化和反序列化。

我無法使用->

1. Java 可序列化作為兩個客戶端的響應對象都沒有實現可序列化接口。
2. Jackson因為響應 object 沒有無參數構造函數，因此在反序列化時顯示以下錯誤。

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.example.Student` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

3. Gson由於出 memory 錯誤：

（下面使用ApacheClient）

序列化：

       Gson gson = new GsonBuilder().setPrettyPrinting().create();
       ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
       OutputStreamWriter writer = new OutputStreamWriter(outputStream);
       gson.toJson(httpResponse, writer);
       writer.flush();

反序列化：

       byte[] data = outputStream.toByteArray();
       ByteArrayInputStream inputStream = new ByteArrayInputStream(data);
       InputStreamReader reader = new InputStreamReader(inputStream);
       HttpResponse res = gson.fromJson(reader, HttpResponse.class);
       System.out.println("HttpResponse-> " + EntityUtils.toString(res.getEntity()));

錯誤：

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Arrays.copyOf(Arrays.java:3332)
    at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:124)
    at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:448)
    at java.lang.StringBuffer.append(StringBuffer.java:276)
    at java.io.StringWriter.write(StringWriter.java:101)
    at com.google.gson.stream.JsonWriter.newline(JsonWriter.java:602)
    at com.google.gson.stream.JsonWriter.beforeValue(JsonWriter.java:646)
    at com.google.gson.stream.JsonWriter.value(JsonWriter.java:532)
    at com.google.gson.internal.bind.TypeAdapters$5.write(TypeAdapters.java:189)
    at com.google.gson.internal.bind.TypeAdapters$5.write(TypeAdapters.java:173)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ArrayTypeAdapter.write(ArrayTypeAdapter.java:95)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:97)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:61)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)

Answer 1

• The first question is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.example.Student` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)表明org.example.Student class 應該聲明一個默認構造函數。 那么什么是默認構造函數呢？ 好的，它只是一個非參數構造函數。

• Java Memory 分析分析JVM ZCD69B4957F06CD818D7BF3DZ619的用法。