Spring-Boot-20-ResponseEntity

1. ResponseEntity处理http响应

1. 标识了整个http响应:状态码、头部信息以及相应体内容
2. 如果要使用ReponseEntity,必须在请求点返回，通常在spring rest中实现。

1. HeadersBuilder:不能设置任何响应体属性
2. BodyBuilder(是上面的子接口)

@GetMapping("/hello")
ResponseEntity hello() {
    return ResponseEntity.ok("Hello World!");
}

1. BodyBuilder accepted();
2. BodyBuilder badRequest();
3. BodyBuilder created(java.net.URI location);
4. HeadersBuilder noContent();
5. HeadersBuilder notFound();
6. BodyBuilder ok();
7. BodyBuilder status(HttpStatus status)
8. BodyBuilder status(int status)

@GetMapping("/age")
ResponseEntity age(@RequestParam("yearOfBirth") int yearOfBirth) {
    if (isInFuture(yearOfBirth)) {
        return ResponseEntity.badRequest()
            .body("Year of birth cannot be in the future");
    }

    return ResponseEntity.status(HttpStatus.OK)
        .body("Your age is " + calculateAge(yearOfBirth));
}

@GetMapping("/age")
ResponseEntity age(@RequestParam("yearOfBirth") int yearOfBirth) {
    if (isInFuture(yearOfBirth)) {
        return new ResponseEntity<>("Year of birth cannot be in the future", HttpStatus.BAD_REQUEST);
    }
    return new ResponseEntity<>("Your age is " + calculateAge(yearOfBirth), HttpStatus.OK);
}

//方式一
@GetMapping("/customHeader")
ResponseEntity customHeader() {
    HttpHeaders headers = new HttpHeaders();
    headers.add("Custom-Header", "foo");
    return new ResponseEntity<>("Custom header set", headers, HttpStatus.OK);
}
//方式二
@GetMapping("/customHeader")
ResponseEntity customHeader() {
    return ResponseEntity.ok()
        .header("Custom-Header", "foo")
        .body("Custom header set");
}

1. .body()返回的是ResponseEntity，而并不是BodyBuilder，需要在最后进行调用。