---
# (DD08) Business Logic — Example.uploadFile() [12 LOC]

| Field | Value |
|-------|-------|
| Fully Qualified Name | `io.github.biezhi.java11.http.Example` |
| Layer | Utility |
| Module | `http` (Package: `io.github.biezhi.java11.http`) |

## 1. Role

### Example.uploadFile()

This method acts as a minimal HTTP client example for uploading a local file to a web endpoint. It creates a fresh Java 11 `HttpClient`, constructs a `POST` request to `http://localhost:8080/upload/`, and streams the contents of `/tmp/files-to-upload.txt` as the request body. The method then sends the request synchronously and prints the returned HTTP status code to standard output.

From a business perspective, the method demonstrates the outbound file-transfer path used by a client application or sample utility when validating an upload service. It does not implement any branching business workflow, persistence logic, or transformation rules; instead, it serves as a reference implementation for how to submit a file to an upload endpoint. The design pattern is straightforward request construction and synchronous dispatch using the Java HTTP client API. In the larger system, it functions as a self-contained sample utility that can be invoked to test whether the upload service is reachable and accepting file payloads.

## 2. Processing Pattern (Detailed Business Logic)

```mermaid
flowchart TD
    START(["uploadFile()"])
    CLIENT(["Create HttpClient with HttpClient.newHttpClient()"])
    REQUEST(["Build HTTP request"])
    URI_NODE(["Set URI to http://localhost:8080/upload/"])
    BODY_NODE(["Set POST body from /tmp/files-to-upload.txt"])
    BUILD_NODE(["Build request object"])
    SEND_NODE(["Send request and discard response body"])
    STATUS_NODE(["Print HTTP status code"])
    END_NODE(["Return / Next"])

    START --> CLIENT
    CLIENT --> REQUEST
    REQUEST --> URI_NODE
    URI_NODE --> BODY_NODE
    BODY_NODE --> BUILD_NODE
    BUILD_NODE --> SEND_NODE
    SEND_NODE --> STATUS_NODE
    STATUS_NODE --> END_NODE
```

**CRITICAL — Constant Resolution:**
The method does not reference in-code constants or conditional constant branches. The request target and source file path are literal values:
- `http://localhost:8080/upload/` — local upload endpoint used for the HTTP `POST`
- `/tmp/files-to-upload.txt` — file path whose contents are uploaded as the request body

## 3. Parameter Analysis

| No | Parameter Name | Type | Business Description |
|----|---------------|------|---------------------|
| - | (none) | - | - |

This method accepts no parameters. Its behavior is fully determined by hard-coded endpoint and file-path literals, and by the local runtime environment that provides the HTTP service and file system access. It also reads no instance fields and depends on no external object state beyond the local file and remote HTTP endpoint.

## 4. CRUD Operations / Called Services

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| C | `HttpRequest.BodyPublishers.ofFile` | N/A | Local file `/tmp/files-to-upload.txt` | Reads the file contents and publishes them as the payload for a file-upload request |
| R | `client.send` | N/A | HTTP response from `http://localhost:8080/upload/` | Sends the upload request and receives the response status for validation |
| R | `response.statusCode` | N/A | HTTP response metadata | Reads the returned status code to determine whether the upload succeeded |

No application-specific SC/CBS method is called by this method. The only operations are Java HTTP client API calls and file streaming.

## 5. Dependency Trace

| # | Caller (Screen/Batch) | Call Chain (Full Path to this Method) | Terminal (SC / CRUD / Entity) |
|---|----------------------|--------------------------------------|-------------------------------|
| 1 | None identified | `Example.uploadFile()` | `HttpRequest.BodyPublishers.ofFile [C] /tmp/files-to-upload.txt` |

No Java caller of `uploadFile()` was found in the repository search. The method currently appears to be a standalone example entry point rather than a shared callback used by another screen, batch, or CBS component.

## 6. Per-Branch Detail Blocks

**Block 1** — [SEQUENCE] `(method entry)` (L103)

> Opens a new HTTP client session for sending the file upload request.

| # | Type | Code |
|---|------|------|
| 1 | SET | `HttpClient client = HttpClient.newHttpClient();` |

**Block 2** — [SEQUENCE] `(request construction)` (L105-L108)

> Builds a single POST request targeting the local upload endpoint.

| # | Type | Code |
|---|------|------|
| 1 | SET | `HttpRequest request = HttpRequest.newBuilder()` |
| 2 | EXEC | `.uri(new URI("http://localhost:8080/upload/"))` |
| 3 | EXEC | `.POST(HttpRequest.BodyPublishers.ofFile(Paths.get("/tmp/files-to-upload.txt")))` |
| 4 | EXEC | `.build();` |

**Block 3** — [SEQUENCE] `(send and capture response)` (L110)

> Submits the request synchronously and captures the HTTP response object.

| # | Type | Code |
|---|------|------|
| 1 | SET | `HttpResponse<Void> response = client.send(request, HttpResponse.BodyHandlers.discarding());` |

**Block 4** — [SEQUENCE] `(report status)` (L111)

> Prints the HTTP result code for console-based validation of the upload outcome.

| # | Type | Code |
|---|------|------|
| 1 | EXEC | `System.out.println(response.statusCode());` |

**Block 5** — [RETURN] `(method exit)` (L112)

| # | Type | Code |
|---|------|------|
| 1 | RETURN | `}` |

## 7. Glossary

| Term | Type | Business Meaning |
|------|------|------------------|
| `uploadFile` | Method name | Example routine that uploads a local file to an HTTP endpoint |
| `HttpClient` | Technical term | Java 11 HTTP client used to send outbound web requests |
| `HttpRequest` | Technical term | Immutable HTTP request object used to define the target URI, method, and body |
| `POST` | HTTP method | Upload-oriented request type that submits data to a server |
| `BodyPublishers.ofFile` | Technical term | Java API that streams file contents as the request body |
| `BodyHandlers.discarding` | Technical term | Response handler that ignores the response body and keeps only status/headers |
| `statusCode` | Technical term | Numeric HTTP result code such as 200 or 404 |
| `localhost` | Hostname | Local machine address used for development or local integration testing |
| `8080` | Port | Common local application port for a development HTTP server |
| `upload` | Business term | Service action for transferring a file into the receiving system |
| `/tmp/files-to-upload.txt` | File path | Local source file whose contents are submitted in the upload request |
| Java 11 | Platform | Runtime version providing the standard HTTP client API used by this method |
---