@RestController
@RequestMapping("/api")
public class UserController {

    @GetMapping("/v1/users/{id}")
    public ResponseEntity<UserV1> getUserV1(@PathVariable Long id) {
        UserV1 user = new UserV1("Alice");
        return ResponseEntity.ok(user);
    }

    @GetMapping("/v2/users/{id}")
    public ResponseEntity<UserV2> getUserV2(@PathVariable Long id) {
        UserV2 user = new UserV2("Alice Smith");
        return ResponseEntity.ok(user);
    }

    // DTOs
    public static class UserV1 {
        public String name;
        public UserV1(String name) { this.name = name; }
    }

    public static class UserV2 {
        public String fullName;
        public UserV2(String fullName) { this.fullName = fullName; }
    }
}

@RestController
public class UserController {

    @GetMapping("/users")
    public ResponseEntity<?> getUser(
            @RequestParam(defaultValue = "v1") String version,
            @RequestParam Long id) {

        return switch (version) {
            case "v1" -> ResponseEntity.ok(new UserV1("Alice"));
            case "v2" -> ResponseEntity.ok(new UserV2("Alice Smith"));
            default -> ResponseEntity.badRequest()
                    .body("Unsupported version: " + version);
        };
    }

    // DTOs 同上
}

@RestController
public class UserController {

    @GetMapping("/users")
    public ResponseEntity<?> getUser(
            @RequestHeader(name = "X-API-Version", defaultValue = "1") String versionStr) {

        int version;
        try {
            version = Integer.parseInt(versionStr);
        } catch (NumberFormatException e) {
            return ResponseEntity.badRequest().body("Invalid version format");
        }

        return switch (version) {
            case 1 -> ResponseEntity.ok(new UserV1("Alice"));
            case 2 -> ResponseEntity.ok(new UserV2("Alice Smith"));
            default -> ResponseEntity.badRequest().body("Unsupported version: " + version);
        };
    }
}

Accept: application/vnd.mycompany.v2+json

@RestController
public class UserController {

    private final ObjectMapper objectMapper = new ObjectMapper();

    @GetMapping(
        value = "/users",
        produces = {
            "application/vnd.mycompany.v1+json",
            "application/vnd.mycompany.v2+json"
        }
    )
    public ResponseEntity<String> getUser(
            @RequestHeader("Accept") String acceptHeader) {

        String version = parseVersionFromAccept(acceptHeader);
        if (version == null) {
            return ResponseEntity.status(HttpStatus.NOT_ACCEPTABLE)
                .body("Accept header must specify v1 or v2.");
        }

        String json;
        String mediaType;

        if ("v1".equals(version)) {
            json = toJson(new UserV1("Alice"));
            mediaType = "application/vnd.mycompany.v1+json";
        } else if ("v2".equals(version)) {
            json = toJson(new UserV2("Alice Smith"));
            mediaType = "application/vnd.mycompany.v2+json";
        } else {
            return ResponseEntity.badRequest().body("Unexpected version: " + version);
        }

        return ResponseEntity.ok()
            .contentType(MediaType.parseMediaType(mediaType))
            .body(json);
    }

    private String parseVersionFromAccept(String accept) {
        if (accept == null) return null;
        if (accept.contains("vnd.mycompany.v1")) return "v1";
        if (accept.contains("vnd.mycompany.v2")) return "v2";
        return null;
    }

    private String toJson(Object obj) {
        try {
            return objectMapper.writeValueAsString(obj);
        } catch (JsonProcessingException e) {
            throw new RuntimeException("Serialization error", e);
        }
    }

    // DTOs
    public static class UserV1 {
        public String name;
        public UserV1(String name) { this.name = name; }
    }

    public static class UserV2 {
        public String fullName;
        public UserV2(String fullName) { this.fullName = fullName; }
    }
}

Accept: application/json;version=2

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
        configurer.favorParameter(false)
                  .ignoreAcceptHeader(false)
                  .defaultContentType(MediaType.APPLICATION_JSON);
    }

    @Bean
    public ContentNegotiationManager contentNegotiationManager() {
        ContentNegotiationManager manager = new ContentNegotiationManager();
        // 默認(rèn)策略保留
        return manager;
    }
}

@GetMapping("/users")
public ResponseEntity<?> getUser(@RequestHeader("Accept") String acceptHeader) {
    // 解析: application/json;version=2
    Map<String, String> params = parseMediaTypeParams(acceptHeader);
    String version = params.get("version");

    // ... 根據(jù) version 構(gòu)造響應(yīng)
}

private Map<String, String> parseMediaTypeParams(String accept) {
    Map<String, String> params = new HashMap<>();
    if (accept != null && accept.contains(";")) {
        String[] parts = accept.split(";");
        for (int i = 1; i < parts.length; i++) {
            String[] kv = parts[i].trim().split("=");
            if (kv.length == 2) {
                params.put(kv[0], kv[1].replaceAll("\"", ""));
            }
        }
    }
    return params;
}