在Java中将JSON Type转换为Byte数组格式

I have a problem when I want to sending data using byte format in UDP protocol, the problem is when I try to create a data with type json object, I can't get the byte format of my data this is my sample code:

我想在UDP协议中使用字节格式发送数据时遇到问题，问题是当我尝试使用json对象创建数据时，我无法得到我的数据的字节格式这是我的示例代码：

    JSONObject obj = new JSONObject();
    obj.put("name", "foo");
    obj.put("num", new Integer(100));
    obj.put("balance", new Double(1000.21));
    obj.put("is_vip", new Boolean(true));
    obj.put("nickname",null);

    sendData = obj.getBytes(); //this is error because not have methos getBytes();

i know my problem but i can't found how to convert json object to byte, any suggestion ?

我知道我的问题，但我找不到如何将json对象转换为字节，任何建议？

4 个解决方案

#1

Get the bytes of the string:

获取字符串的字节：

obj.toString().getBytes(theCharset);

#2

Assuming the JSONObject you mention is from this, you can get the bytes like below

假设您提到的JSONObject来自于此，您可以获得如下所示的字节

sendData = obj.toString().getBytes("utf-8");

#3

To avoid unnecessary conversion from String to byte[] which enforces encoding based on the provided charset, I prefer to use JsonWriter directly with ByteArrayOutputStream for instance (JsonValue subtypes use JsonWriter with StringWriter):

为了避免从String到byte []的不必要转换，它基于提供的字符集强制执行编码，我更喜欢直接使用JsonWriter和ByteArrayOutputStream（JsonValue子类型使用带有StringWriter的JsonWriter）：

ByteArrayOutputStream stream = new ByteArrayOutputStream();
Json.createWriter(stream).write(obj);

byte[] sendData = stream.toByteArray()

System.out.println("Bytes array: " + sendData);
System.out.println("As a string: " + stream.toString());

Additionally, one can even enable pretty printing as follows:

此外，甚至可以启用漂亮的打印，如下所示：

Json.createWriterFactory(
            Collections.singletonMap(JsonGenerator.PRETTY_PRINTING, true))
        .createWriter(stream)
        .write(obj);

The only sad thing is that it's not an one-liner. You'd need 3 at least (given the fact that you omit calling JsonWriter.close() which is unnecessary in this context).

唯一可悲的是，它不是一个单行。你至少需要3个（考虑到你省略了调用JsonWriter.close（）的事实，这在这个上下文中是不必要的）。

#4

Use utility class from ObjectMapper of jackson-databind project, ie objectMapper.writeValueAsBytes(dto) returns byte[]

使用来自jackson-databind项目的ObjectMapper的实用程序类，即objectMapper.writeValueAsBytes（dto）返回byte []

@Autowired
private ObjectMapper objectMapper;

ContractFilterDTO filter = new ContractFilterDTO();
    mockMvc.perform(post("/api/customer/{ico}", "44077866")
            .contentType(MediaType.APPLICATION_JSON_UTF8_VALUE)
            .content(objectMapper.writeValueAsBytes(filter)))...

Maven dependency:

Maven依赖：

<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.8.8.1</version>
</dependency>

#1