我试图通过使用ObjectMapper记录响应来将一个复杂对象序列化为某个地方包含bytebuffer的字符串。 这会改变bytebuffer中的光标位置,只会破坏响应。
我正在使用的代码段:
import org.codehaus.jackson.map.ObjectMapper;
private static final ObjectMapper MAPPER = new ObjectMapper();
public static String serializeToString(final Object obj) {
Preconditions.checkArgument(obj != null, "Object to be serialized is null");
try {
final String str = MAPPER.writeValueAsString(obj);
if (Strings.isNullOrEmpty(str)) {
log.warn("Serialized to null/empty string");
}
return str;
} catch (final JsonGenerationException e) {
throw new IllegalArgumentException("Json generation exception occured in de-serializing obj", e);
} catch (final JsonMappingException e) {
throw new IllegalArgumentException("Json mapping exception occured in de-serializing obj", e);
} catch (final IOException e) {
throw new IllegalArgumentException("IO exception occured in de-serializing obj", e);
}
}
我在上面的方法中传递了一个内部有bytebuffer的复杂对象。 我在调用上面的方法之前和之后打印了bytebuffer。
public static void main(final String[] args) throws SecurityException, NoSuchMethodException {
final String x =
"Random data i am using for this test for byte buffer. Random data i am using for this test for byte buffer";
final byte[] byteArr = x.getBytes();
final ByteBuffer bb = ByteBuffer.wrap(byteArr);
System.out.println("before bytebuffer :" + bb);
String stringData = SerializerUtil.serializeToString(bb); // In real i am passing a complex structure having
// bytebuffer inside
System.out.println(stringData);
System.out.println("after bytebuffer :" + bb);
}
输出:
before bytebuffer :java.nio.HeapByteBuffer[pos=0 lim=106 cap=106]
{"short":21089,"char":"\u6e64","int":1869422692,"long":7022344510808023405,"float":2.0790493E-19,"double":6.687717052371733E223,"direct":false,"readOnly":false}
after bytebuffer :java.nio.HeapByteBuffer[pos=28 lim=106 cap=106]
(pos = 0到pos = 28)位置的这种变化只会破坏发送的响应。我们有没有办法将这个复杂的对象转换为字符串而不影响byteBuffer?
任何帮助都非常感激。
答案 0 :(得分:1)
显然,您不希望将ByteBuffer
属性序列化为另一个结构化类,而只是将内容序列化为字符串。一种方法是在方法上使用@JsonProperty
注释来告诉映射器使用该方法,而不是尝试直接序列化字段。假设你有这样的bean:
class Stuff {
private ByteBuffer data;
public Stuff() {
}
public Stuff(ByteBuffer data) {
super();
this.data = data;
}
public ByteBuffer getData() {
return data;
}
public void setData(ByteBuffer data) {
this.data = data;
}
@JsonProperty(value = "data")
public String convertData() {
return new String(data.array());
}
@JsonProperty("data")
public void convertData(String s) {
data = ByteBuffer.wrap(s.getBytes());
}
}
映射器现在将使用convertData方法对ByteBuffer数据属性进行序列化和反序列化,您仍然可以使用普通的java bean属性方法。
更新:
由于无法更改序列化类,因此这是使用som高级JACKSON内容的替代方法。首先,创建自定义序列化程序和反序列化程序:
static class ByteBufferSerializer extends JsonSerializer<ByteBuffer> {
@Override
public void serialize(ByteBuffer value, JsonGenerator jgen,
SerializerProvider provider) throws IOException,
JsonProcessingException {
jgen.writeString(new String(value.array()));
}
}
static class ByteBufferDeserializer extends JsonDeserializer<ByteBuffer> {
@Override
public ByteBuffer deserialize(JsonParser jp,
DeserializationContext context) throws IOException,
JsonProcessingException {
return ByteBuffer.wrap(jp.getText().getBytes());
}
}
然后,创建一个Mixin接口,为我们在真实目标类中无法提供的属性提供注释:
static interface Mixin {
@JsonSerialize(using = ByteBufferSerializer.class, contentAs = String.class)
ByteBuffer getData();
@JsonDeserialize(using = ByteBufferDeserializer.class, contentAs = String.class)
void setData(ByteBuffer data);
}
此外,创建一个用于配置对象映射器的模块,并添加mixin接口:
static class MyModule extends SimpleModule {
public MyModule() {
super("ByteBuffer wrangling");
}
@Override
public void setupModule(SetupContext context) {
context.setMixInAnnotations(Stuff.class, Mixin.class);
}
}
最后,使用映射器注册模块:
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new MyModule());
Voilà,小菜一碟! : - )