SpringMVC - 响应处理
2025/12/12大约 3 分钟
SpringMVC - 响应处理
返回视图
返回视图名称
@Controller
public class ViewController {
// 返回逻辑视图名，由视图解析器解析
@GetMapping("/hello")
public String hello() {
return "hello"; // 解析为 /WEB-INF/views/hello.jsp
}
// 带路径的视图
@GetMapping("/user/list")
public String userList() {
return "user/list"; // 解析为 /WEB-INF/views/user/list.jsp
}
}转发与重定向
@Controller
public class ForwardController {
// 转发（forward:）- URL 不变，一次请求
@GetMapping("/forward")
public String forward() {
return "forward:/target";
}
// 重定向（redirect:）- URL 改变，两次请求
@GetMapping("/redirect")
public String redirect() {
return "redirect:/target";
}
// 重定向到外部地址
@GetMapping("/external")
public String external() {
return "redirect:https://www.baidu.com";
}
}Model 传递数据
@Controller
public class ModelController {
// 使用 Model
@GetMapping("/model")
public String model(Model model) {
model.addAttribute("name", "张三");
model.addAttribute("age", 25);
return "user";
}
// 使用 ModelMap
@GetMapping("/modelMap")
public String modelMap(ModelMap modelMap) {
modelMap.addAttribute("name", "张三");
return "user";
}
// 使用 Map
@GetMapping("/map")
public String map(Map<String, Object> map) {
map.put("name", "张三");
return "user";
}
// 使用 ModelAndView
@GetMapping("/mav")
public ModelAndView modelAndView() {
ModelAndView mav = new ModelAndView();
mav.setViewName("user");
mav.addObject("name", "张三");
return mav;
}
}返回 JSON
@ResponseBody
@Controller
public class JsonController {
// 返回单个对象
@GetMapping("/user")
@ResponseBody
public User getUser() {
User user = new User();
user.setId(1L);
user.setName("张三");
return user; // 自动转为 JSON
}
// 返回集合
@GetMapping("/users")
@ResponseBody
public List<User> getUsers() {
return Arrays.asList(
new User(1L, "张三"),
new User(2L, "李四")
);
}
// 返回 Map
@GetMapping("/map")
@ResponseBody
public Map<String, Object> getMap() {
Map<String, Object> map = new HashMap<>();
map.put("code", 200);
map.put("message", "success");
return map;
}
}@RestController
@RestController = @Controller + @ResponseBody
@RestController
@RequestMapping("/api")
public class ApiController {
@GetMapping("/user")
public User getUser() {
return new User(1L, "张三"); // 自动转为 JSON
}
@GetMapping("/users")
public List<User> getUsers() {
return userService.findAll();
}
}统一响应格式
// 统一响应类
public class Result<T> {
private Integer code;
private String message;
private T data;
public static <T> Result<T> success(T data) {
Result<T> result = new Result<>();
result.setCode(200);
result.setMessage("success");
result.setData(data);
return result;
}
public static <T> Result<T> error(Integer code, String message) {
Result<T> result = new Result<>();
result.setCode(code);
result.setMessage(message);
return result;
}
// getter/setter...
}
// 使用
@RestController
@RequestMapping("/api")
public class ApiController {
@GetMapping("/user/{id}")
public Result<User> getUser(@PathVariable Long id) {
User user = userService.findById(id);
if (user != null) {
return Result.success(user);
}
return Result.error(404, "用户不存在");
}
}ResponseEntity
精确控制响应状态码和响应头：
@RestController
public class ResponseEntityController {
@GetMapping("/user/{id}")
public ResponseEntity<User> getUser(@PathVariable Long id) {
User user = userService.findById(id);
if (user != null) {
return ResponseEntity.ok(user);
}
return ResponseEntity.notFound().build();
}
@PostMapping("/user")
public ResponseEntity<User> createUser(@RequestBody User user) {
User saved = userService.save(user);
URI location = URI.create("/api/user/" + saved.getId());
return ResponseEntity.created(location).body(saved);
}
// 自定义响应头
@GetMapping("/custom")
public ResponseEntity<String> custom() {
HttpHeaders headers = new HttpHeaders();
headers.add("X-Custom-Header", "custom-value");
return new ResponseEntity<>("Hello", headers, HttpStatus.OK);
}
}文件下载
@Controller
public class DownloadController {
// 方式一：使用 ResponseEntity
@GetMapping("/download")
public ResponseEntity<byte[]> download() throws IOException {
// 读取文件
Path path = Paths.get("/path/to/file.pdf");
byte[] content = Files.readAllBytes(path);
// 设置响应头
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
headers.setContentDispositionFormData("attachment",
URLEncoder.encode("文件.pdf", "UTF-8"));
return new ResponseEntity<>(content, headers, HttpStatus.OK);
}
// 方式二：使用 HttpServletResponse
@GetMapping("/download2")
public void download2(HttpServletResponse response) throws IOException {
Path path = Paths.get("/path/to/file.pdf");
response.setContentType("application/octet-stream");
response.setHeader("Content-Disposition",
"attachment; filename=" + URLEncoder.encode("文件.pdf", "UTF-8"));
Files.copy(path, response.getOutputStream());
}
}JSON 配置
Jackson 配置
@Configuration
public class JacksonConfig {
@Bean
public ObjectMapper objectMapper() {
ObjectMapper mapper = new ObjectMapper();
// 日期格式
mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
// 时区
mapper.setTimeZone(TimeZone.getTimeZone("Asia/Shanghai"));
// 忽略空值
mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
// 忽略未知属性
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
return mapper;
}
}常用 Jackson 注解
public class User {
private Long id;
@JsonProperty("user_name") // JSON 字段名
private String name;
@JsonIgnore // 不序列化
private String password;
@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "Asia/Shanghai")
private Date createTime;
@JsonInclude(JsonInclude.Include.NON_NULL) // 空值不序列化
private String remark;
}内容协商
根据请求返回不同格式的数据：
@RestController
public class ContentNegotiationController {
// 根据 Accept 头返回不同格式
@GetMapping(value = "/user",
produces = {MediaType.APPLICATION_JSON_VALUE, MediaType.APPLICATION_XML_VALUE})
public User getUser() {
return new User(1L, "张三");
}
}配置内容协商：
@Configuration
public class WebConfig implements WebMvcConfigurer {
@Override
public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
configurer
.favorParameter(true) // 支持参数方式
.parameterName("format") // 参数名
.defaultContentType(MediaType.APPLICATION_JSON)
.mediaType("json", MediaType.APPLICATION_JSON)
.mediaType("xml", MediaType.APPLICATION_XML);
}
}访问方式：
/user- 返回 JSON（默认）/user?format=xml- 返回 XML/user（Accept: application/xml）- 返回 XML