RequestBody

RequestBody is a term used in HTTP client libraries to describe the data carried in the body of an HTTP request. It represents the payload that a client sends to a server, as opposed to data sent in the URL query string or in headers. A RequestBody typically includes both the content itself and metadata such as the media type (also called Content-Type) and, sometimes, the content length.

In practice, a RequestBody can carry various kinds of data, including plain text, JSON, binary data, form-encoded data, or multipart form data used for file uploads. Implementations provide ways to create a body from strings, byte arrays, files, or input streams, and to specify the appropriate content type. Some libraries offer specialized subclasses or builders for common formats, such as simple text bodies, form bodies, or multipart bodies that combine several parts.

In widely used ecosystems such as OkHttp and Retrofit, RequestBody is used to supply the payload to requests. It may be created directly for raw payloads or produced by higher-level converters that serialize objects to a desired format (for example, JSON). For multipart requests, separate structures often model the individual parts, while a RequestBody represents the overall payload.

Key considerations when using RequestBody include memory usage and performance (buffered versus streaming bodies), the ability to stream large data, and the correct specification of the content length or transfer encoding. Understanding the content type and encoding is essential for interoperability with servers.