使用jackson在json中发送字节数组
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Sending a byte array in json using Hymanson
提问by Sudhagar Sachin
I want to form a JSON with two fields mimetype and value.The value field should take byte array as its value.
我想用两个字段 mimetype 和 value 形成一个 JSON。 value 字段应该将字节数组作为它的值。
{
"mimetype":"text/plain",
"value":"dasdsaAssadsadasd212sadasd"//this value is of type byte[]
}
How can I accomplish this task?
我怎样才能完成这个任务？
As of now I am using toString()method to convert the byte array into String and form the JSON.
截至目前，我正在使用toString()方法将字节数组转换为字符串并形成 JSON。
回答by StaxMan
If you are using Hymanson for JSON parsing, it can automatically convert byte[]to/from Base64 encoded Strings via data-binding.
如果您使用 Hymanson 进行 JSON 解析，它可以byte[]通过数据绑定自动转换为/从 Base64 编码的字符串。
Or, if you want low-level access, both JsonParserand JsonGeneratorhave binary access methods (writeBinary, readBinary) to do the same at level of JSON token stream.
或者，如果你想低级别的访问，双方JsonParser并JsonGenerator有二进制访问方法（writeBinary，readBinary）做同样的JSON令牌流的水平。
For automatic approach, consider POJO like:
对于自动方法，请考虑 POJO，例如：
public class Message {
public String mimetype;
public byte[] value;
}
and to create JSON, you could do:
要创建 JSON，您可以执行以下操作：
Message msg = ...;
String jsonStr = new ObjectMapper().writeValueAsString(msg);
or, more commonly would write it out with:
或者，更常见的是将它写出来：
OutputStream out = ...;
new ObjectMapper().writeValue(out, msg);
回答by Alberto Estrella
You can write your own CustomSerializer like this one:
您可以像这样编写自己的 CustomSerializer：
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.
这个返回一个无符号字节数组表示而不是 Base64 字符串。
How to use it with your POJO:
如何在您的 POJO 中使用它：
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:
这是它的输出示例：
{
"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.
PS：这个序列化程序是我在 StackOverflow 上找到的一些答案的混合。
回答by Dreen
You might want to use Base64which 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.
您可能希望使用Base64将二进制数据转换为字符串。大多数编程语言都有 base64 编码和解码的实现。如果您想在浏览器中解码/编码，请参阅此问题。
