multipart parsing, request body access, and chunked input stream support
This commit is contained in:
Relism
@@ -0,0 +1,98 @@
|
||||
# Request Body
|
||||
|
||||
`req.body()` returns a `RequestBody` — a lazy accessor that exposes the HTTP request body in
|
||||
two mutually exclusive modes. Choose one per handler based on the payload size and how you
|
||||
intend to consume it.
|
||||
|
||||
---
|
||||
|
||||
## Two modes
|
||||
|
||||
### `bytes()` — materialise
|
||||
|
||||
```java
|
||||
byte[] body = req.body().bytes();
|
||||
```
|
||||
|
||||
Reads the full body into a `byte[]` and caches the result. Safe to call multiple times — the
|
||||
second call returns the same cached array, no I/O is performed again.
|
||||
|
||||
Use for:
|
||||
- JSON parsing (`new String(body, UTF_8)` then parse)
|
||||
- Small form data
|
||||
- Any payload that must be inspected in full before responding
|
||||
|
||||
**Limit:** throws `IllegalStateException` if `Content-Length` exceeds `Integer.MAX_VALUE`
|
||||
(~2 GB). For larger bodies use `stream()`.
|
||||
|
||||
**Chunked bodies:** reads until `ChunkedInputStream` signals EOF, then caches.
|
||||
|
||||
---
|
||||
|
||||
### `stream()` — zero-copy
|
||||
|
||||
```java
|
||||
InputStream in = req.body().stream();
|
||||
```
|
||||
|
||||
Returns a bounded `InputStream` without allocating the full body upfront.
|
||||
|
||||
Use for:
|
||||
- Large file uploads
|
||||
- Bodies passed directly to disk, a database, or another stream
|
||||
- Multipart parsing (via `Multipart.of(req)` which calls this internally)
|
||||
|
||||
**Fixed-length bodies:** a `SequenceInputStream` of any pre-buffered header bytes (from the
|
||||
`RequestParser` read buffer, already in memory) followed by a bounded view of the socket
|
||||
stream. The small pre-buffered slice costs nothing extra.
|
||||
|
||||
**Chunked bodies:** returns the raw `ChunkedInputStream` directly. It de-chunks on the fly —
|
||||
reads the hex chunk-size line, the data, and the trailing CRLF — and signals EOF at the end
|
||||
of the last chunk, leaving the socket positioned correctly for the next keep-alive request.
|
||||
|
||||
**After `bytes()`:** if the body was already materialised, `stream()` returns a fresh
|
||||
`ByteArrayInputStream` over the cached array. No I/O is performed.
|
||||
|
||||
---
|
||||
|
||||
## Mutual exclusivity
|
||||
|
||||
```java
|
||||
// SAFE — pick one mode
|
||||
byte[] b = req.body().bytes();
|
||||
InputStream s = req.body().stream();
|
||||
|
||||
// UNSAFE — bytes() then stream() is safe (stream() wraps the cache)
|
||||
// UNSAFE — stream() partially read, then bytes() → undefined results
|
||||
```
|
||||
|
||||
The rule: if you call `stream()` first and partially read it, calling `bytes()` afterwards
|
||||
will either throw (if `contentLength` > 2 GB) or read only the remaining socket bytes into
|
||||
the array, missing the already-consumed portion.
|
||||
|
||||
---
|
||||
|
||||
## Checking the size
|
||||
|
||||
```java
|
||||
long size = req.body().contentLength();
|
||||
```
|
||||
|
||||
- **> 0** — fixed-length body; exact byte count
|
||||
- **== 0** — empty body (`Content-Length: 0` or no body present)
|
||||
- **== -1** — `Transfer-Encoding: chunked`; size is unknown upfront
|
||||
|
||||
```java
|
||||
boolean empty = req.body().isEmpty(); // true when contentLength == 0
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## Decision guide
|
||||
|
||||
| Payload size | Encoding | Use |
|
||||
|--------------------|-----------|----------------|
|
||||
| < 2 GB, fully needed | any | `bytes()` |
|
||||
| Any size, pass-through | any | `stream()` |
|
||||
| Multipart form | any | `Multipart.of(req)` (uses `stream()` internally) |
|
||||
| Size unknown | chunked | `stream()` |
|
||||
@@ -0,0 +1,190 @@
|
||||
# Multipart
|
||||
|
||||
`Multipart` is a lazy streaming `multipart/form-data` parser. It reads from `req.body().stream()`
|
||||
— the request body is **never fully materialised**. Text fields are buffered eagerly (they are
|
||||
small by definition); file part bodies are exposed as zero-copy `InputStream`s backed directly
|
||||
by the socket.
|
||||
|
||||
---
|
||||
|
||||
## Creating a parser
|
||||
|
||||
```java
|
||||
Multipart mp = Multipart.of(req);
|
||||
```
|
||||
|
||||
Throws `IllegalArgumentException` if the request is not `multipart/form-data` or the
|
||||
`boundary` parameter is missing. Throws `IOException` if the initial stream read fails (the
|
||||
parser skips the opening `--boundary\r\n` preamble on construction).
|
||||
|
||||
---
|
||||
|
||||
## Reading text fields — `field(String name)`
|
||||
|
||||
```java
|
||||
String userId = mp.field("userId"); // null if absent or a file part
|
||||
String width = mp.field("width");
|
||||
```
|
||||
|
||||
Scans forward through the stream until the named text field is found. Text parts encountered
|
||||
along the way are buffered eagerly. File bodies encountered along the way are **drained
|
||||
silently** (discarded without heap allocation).
|
||||
|
||||
**Order-independent for text:** once a text field has been scanned, it is cached. Calling
|
||||
`mp.field("userId")` after `mp.field("width")` will hit the cache if `userId` was encountered
|
||||
first in the stream.
|
||||
|
||||
Returns `null` if the field is absent or if the named part is a file (has a `filename`
|
||||
attribute). Never returns file content.
|
||||
|
||||
---
|
||||
|
||||
## Reading file parts — `file(String name)`
|
||||
|
||||
```java
|
||||
Part avatar = mp.file("avatar"); // null if absent or a text field
|
||||
```
|
||||
|
||||
Scans forward until the named file part is found. Text parts encountered along the way are
|
||||
buffered (accessible later via `field()`). Earlier file bodies encountered along the way are
|
||||
drained silently.
|
||||
|
||||
The returned `Part`'s stream is backed by the socket. **Consume it before calling any other
|
||||
scan method** — calling `mp.field()`, `mp.file()`, or `mp.parts()` will drain the active
|
||||
stream automatically, but any bytes already read are gone.
|
||||
|
||||
Returns `null` if absent or if the named part is a text field.
|
||||
|
||||
---
|
||||
|
||||
## Collecting multiple parts — `parts(String name)` and `parts()`
|
||||
|
||||
```java
|
||||
List<Part> files = mp.parts("files"); // all parts named "files"
|
||||
List<Part> all = mp.parts(); // every part in declaration order
|
||||
```
|
||||
|
||||
Forces a **full scan**. All file bodies are materialised into `byte[]` arrays — accept this
|
||||
heap cost explicitly when calling these methods. Useful for bulk uploads where you need all
|
||||
files before processing any of them.
|
||||
|
||||
`parts()` must be called before any `file()` call if you need all file parts, since a previous
|
||||
`file()` call may have consumed some of them from the stream.
|
||||
|
||||
---
|
||||
|
||||
## The `Part` object
|
||||
|
||||
Every part — whether text or file — is returned as a `Part`.
|
||||
|
||||
### Metadata
|
||||
|
||||
```java
|
||||
part.name() // field name from Content-Disposition
|
||||
part.filename() // original filename, null for text fields
|
||||
part.contentType() // declared Content-Type, null if not present
|
||||
part.isFile() // true when filename() != null
|
||||
```
|
||||
|
||||
### Body access
|
||||
|
||||
```java
|
||||
// Zero-copy stream — the default
|
||||
InputStream in = part.stream();
|
||||
|
||||
// Explicit materialisation — opt-in heap allocation
|
||||
byte[] data = part.materialize();
|
||||
|
||||
// UTF-8 convenience — materialises if needed, result is cached
|
||||
String text = part.text();
|
||||
```
|
||||
|
||||
#### `stream()`
|
||||
|
||||
For **buffered parts** (text fields and `parts()` results): returns a fresh
|
||||
`ByteArrayInputStream` over the cached `byte[]`. Repeatable, no I/O.
|
||||
|
||||
For **streaming file parts** (from `file()`): returns the raw bounded socket `InputStream`.
|
||||
**Read it once only**, and before requesting the next part.
|
||||
|
||||
#### `materialize()`
|
||||
|
||||
Reads the full part body into a `byte[]` and caches it. Safe to call multiple times on
|
||||
buffered parts (returns the same array). For streaming file parts, triggers a full socket read
|
||||
on the first call; subsequent calls return the cached array.
|
||||
|
||||
#### `text()`
|
||||
|
||||
Convenience over `materialize()`. Decodes the body as UTF-8. Result is cached.
|
||||
|
||||
---
|
||||
|
||||
## Memory model
|
||||
|
||||
| Operation | Heap cost |
|
||||
|---|---|
|
||||
| `Multipart.of(req)` | 8 KB window buffer + boundary bytes |
|
||||
| `mp.field("x")` | body of the text field only (~bytes of the value) |
|
||||
| `mp.file("f")` | none — body is a bounded socket stream |
|
||||
| `part.stream()` on a file | none |
|
||||
| `part.materialize()` on a file | full file size |
|
||||
| `mp.parts()` | full body of every part |
|
||||
| Draining a file body (implicit) | 8 KB reused drain buffer |
|
||||
|
||||
---
|
||||
|
||||
## Ordering constraints and safe patterns
|
||||
|
||||
### Pattern 1 — text fields + one file (most common)
|
||||
|
||||
Text fields are accessible in any order. The file is streamed zero-copy.
|
||||
|
||||
```java
|
||||
Multipart mp = Multipart.of(req);
|
||||
String userId = mp.field("userId"); // order doesn't matter for text
|
||||
String label = mp.field("label");
|
||||
Part file = mp.file("file"); // stream it after fields
|
||||
|
||||
Files.copy(file.stream(), destination, StandardCopyOption.REPLACE_EXISTING);
|
||||
return res.body("saved " + file.filename());
|
||||
```
|
||||
|
||||
### Pattern 2 — echo large file (zero heap)
|
||||
|
||||
```java
|
||||
Part file = Multipart.of(req).file("file");
|
||||
return res.chunked(file.stream()); // socket-in → chunked-out, never touches heap
|
||||
```
|
||||
|
||||
### Pattern 3 — bulk upload (accept the heap cost)
|
||||
|
||||
```java
|
||||
List<Part> files = Multipart.of(req).parts("files");
|
||||
for (Part f : files) {
|
||||
Files.write(dir.resolve(f.filename()), f.materialize());
|
||||
}
|
||||
```
|
||||
|
||||
### Pattern 4 — mixed order (file before text in the form)
|
||||
|
||||
If the form declares the file before a text field and you need the text first,
|
||||
`field()` will drain the file body silently to reach the text part. The file is then gone.
|
||||
Either reorder the form fields or use `parts()` if you need both.
|
||||
|
||||
```java
|
||||
// Form order: file, then userId
|
||||
// This works — file is drained silently, userId is buffered
|
||||
String userId = mp.field("userId");
|
||||
|
||||
// But now mp.file("file") returns null — already drained
|
||||
```
|
||||
|
||||
If you need both, use `parts()` upfront:
|
||||
|
||||
```java
|
||||
List<Part> all = mp.parts();
|
||||
Part file = all.stream().filter(Part::isFile).findFirst().orElse(null);
|
||||
String userId = all.stream().filter(p -> "userId".equals(p.name())).findFirst()
|
||||
.map(p -> { try { return p.text(); } catch (IOException e) { throw new UncheckedIOException(e); } })
|
||||
.orElse(null);
|
||||
```
|
||||
@@ -0,0 +1,104 @@
|
||||
# Request
|
||||
|
||||
The `Request` object is the immutable view of an incoming HTTP/1.1 request passed to every
|
||||
handler. It is constructed by `RequestParser`, path/query parameters are injected once by the
|
||||
router, and then it is handed to your handler unchanged.
|
||||
|
||||
```java
|
||||
server.get("/users/{id}", (req, res) -> { ... });
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## Method and path
|
||||
|
||||
```java
|
||||
HttpMethod method = req.method(); // GET, POST, PUT, …
|
||||
String path = req.path(); // "/users/42" — decoded UTF-8, no query string
|
||||
```
|
||||
|
||||
`path()` allocates a `String` by decoding the underlying `ByteView`. It is a convenience for
|
||||
handlers that need the raw path; the router itself never calls it (it works on the `ByteView`
|
||||
directly for zero-alloc routing).
|
||||
|
||||
---
|
||||
|
||||
## Headers
|
||||
|
||||
```java
|
||||
String ct = req.header("Content-Type"); // first value, or null
|
||||
List<String> accepts = req.headers("Accept"); // all values in order
|
||||
List<String> all = req.headers(); // every header value
|
||||
```
|
||||
|
||||
Lookup is **case-insensitive**: `"content-type"` and `"Content-Type"` resolve to the same header.
|
||||
`header()` returns `null` if the header is absent. `headers()` returns an empty list.
|
||||
|
||||
---
|
||||
|
||||
## Path parameters
|
||||
|
||||
Path parameters are declared in the route pattern with `{name}` syntax and injected by the
|
||||
router before the handler runs.
|
||||
|
||||
```java
|
||||
server.get("/users/{id}/orders/{orderId}", (req, res) -> {
|
||||
String id = req.param("id");
|
||||
String orderId = req.param("orderId");
|
||||
});
|
||||
```
|
||||
|
||||
`param()` returns `null` if the route has no such parameter or is not parametric at all.
|
||||
It never throws.
|
||||
|
||||
---
|
||||
|
||||
## Query parameters
|
||||
|
||||
The query string is parsed lazily on the first `query()` or `queries()` call and cached for
|
||||
the lifetime of the request.
|
||||
|
||||
```java
|
||||
// GET /search?q=flash&page=2&tag=java&tag=jvm
|
||||
|
||||
String q = req.query("q"); // "flash"
|
||||
String page = req.query("page"); // "2"
|
||||
List<String> tags = req.queries("tag"); // ["java", "jvm"]
|
||||
String miss = req.query("absent"); // null
|
||||
```
|
||||
|
||||
`query()` returns the first value for duplicate keys. `queries()` returns all values in
|
||||
declaration order. Both return `null` / empty list for absent parameters, never throw.
|
||||
|
||||
---
|
||||
|
||||
## Body
|
||||
|
||||
See [BODY.md](BODY.md) for a full reference. Quick summary:
|
||||
|
||||
```java
|
||||
// Small payloads — materialise into byte[]
|
||||
byte[] json = req.body().bytes();
|
||||
|
||||
// Large payloads — stream without heap allocation
|
||||
InputStream in = req.body().stream();
|
||||
|
||||
// Check size before choosing
|
||||
long size = req.body().contentLength(); // -1 if Transfer-Encoding: chunked
|
||||
```
|
||||
|
||||
The two modes are **mutually exclusive per request**. Calling `stream()` after `bytes()` returns
|
||||
a `ByteArrayInputStream` over the cached array; calling `bytes()` after `stream()` has been
|
||||
partially read produces undefined results.
|
||||
|
||||
---
|
||||
|
||||
## Keep-alive and drain
|
||||
|
||||
After the response is fully written to the socket, the server calls `req.drain()` automatically
|
||||
on keep-alive connections. This discards any unread body bytes so the socket is correctly
|
||||
positioned for the next pipelined request. You never need to call this yourself.
|
||||
|
||||
**Important:** drain happens *after* the response write, not immediately after the handler
|
||||
returns. This matters for streaming responses that consume the request body on a separate thread
|
||||
(e.g. a pipe-fed echo): by the time drain runs, the body has already been consumed.
|
||||
Reference in New Issue
Block a user