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);
byte[] field, yes. Some other kind of data uses different converters (for example query parameters).
readBinaryValue is that it expects the binary to be base 64 encoded, (standard JSON). However in the wil it's possible to see non standard JSON document that may contain binary data.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.
