I want to form a JSON with two fields mimetype and value.The value field should take byte array as its value.
{
"mimetype":"text/plain",
"value":"dasdsaAssadsadasd212sadasd"//this value is of type byte[]
}
How can I accomplish this task?
As of now I am using toString() method to convert the byte array into String and form the JSON.
If you are using Jackson for JSON parsing, it can automatically convert byte[] to/from Base64 encoded Strings via data-binding.
Or, if you want low-level access, both JsonParser and JsonGenerator have binary access methods (writeBinary, readBinary) to do the same at level of JSON token stream.
For automatic approach, consider POJO like:
public class Message {
public String mimetype;
public byte[] value;
}
and to create JSON, you could do:
Message msg = ...;
String jsonStr = new ObjectMapper().writeValueAsString(msg);
or, more commonly would write it out with:
OutputStream out = ...;
new ObjectMapper().writeValue(out, msg);
You can write your own CustomSerializer like this one:
public class ByteArraySerializer extends JsonSerializer<byte[]> {
@Override
public void serialize(byte[] bytes, JsonGenerator jgen,
SerializerProvider provider) throws IOException,
JsonProcessingException {
jgen.writeStartArray();
for (byte b : bytes) {
jgen.writeNumber(unsignedToBytes(b));
}
jgen.writeEndArray();
}
private static int unsignedToBytes(byte b) {
return b & 0xFF;
}
}
This one returns an unsigned byte array representation instead of a Base64 string.
How to use it with your POJO:
public class YourPojo {
@JsonProperty("mimetype")
private String mimetype;
@JsonProperty("value")
private byte[] value;
public String getMimetype() { return this.mimetype; }
public void setMimetype(String mimetype) { this.mimetype = mimetype; }
@JsonSerialize(using= com.example.yourapp.ByteArraySerializer.class)
public byte[] getValue() { return this.value; }
public void setValue(String value) { this.value = value; }
}
And here is an example of it's output:
{
"mimetype": "text/plain",
"value": [
81,
109,
70,
122,
90,
83,
65,
50,
78,
67,
66,
84,
100,
72,
74,
108,
89,
87,
48,
61
]
}
P.S.: This serializer is a mix of some answers that I found on StackOverflow.
You might want to use Base64 which converts binary data to a string. Most programming languages have implementations of base64 encoding and decoding. If you want to decode/encode in a browser, see this question.
