講點(diǎn)實(shí)用的小技巧，學(xué)習(xí)前端之后才發(fā)現(xiàn)以前寫(xiě)的代碼真是給前端兒搞了不少事，在此誠(chéng)懇道歉

單頁(yè)應(yīng)用越來(lái)越多以及移動(dòng)化之后，服務(wù)化已經(jīng)是老生常談了，在前文代碼的基礎(chǔ)上做些簡(jiǎn)單的通用模塊的處理，后端返回結(jié)果的不一致性真的會(huì)給前端帶來(lái)很大的麻煩，故此為止：

1. 全局異常捕捉及處理
2. REST FULL基本常見(jiàn)規(guī)范

直接貼核心代碼。統(tǒng)一返回結(jié)果RestResult

public class RestResult<T> {

    private boolean result;
    private String message;
    private T data;

    private RestResult() {}

    public static <T> RestResult<T> newInstance() {
        return new RestResult<>();
    }

    // ...setter and getter

    @Override
    public String toString() {
        return "RestResult{" +
                "result=" + result +
                ", message='" + message + '\'' +
                ", data=" + data +
                '}';
    }
}

result工具類RestResultGenerator

/**
 * Created by kaenry on 2016/9/20.
 * RestResultGenerator
 */
public class RestResultGenerator {

    private static final Logger LOGGER = LoggerFactory.getLogger(RestResultGenerator.class);

    /**
     * normal
     * @param success
     * @param data
     * @param message
     * @param <T>
     * @return
     */
    public static <T> RestResult<T> genResult(boolean success, T data, String message) {
        RestResult<T> result = RestResult.newInstance();
        result.setResult(success);
        result.setData(data);
        result.setMessage(message);
        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug("generate rest result:{}", result);
        }
        return result;
    }

    /**
     * success
     * @param data
     * @param <T>
     * @return
     */
    public static <T> RestResult<T> genSuccessResult(T data) {

        return genResult(true, data, null);
    }

    /**
     * error message
     * @param message error message
     * @param <T>
     * @return
     */
    public static <T> RestResult<T> genErrorResult(String message) {

        return genResult(false, null, message);
    }

    /**
     * error
     * @param error error enum
     * @param <T>
     * @return
     */
    public static <T> RestResult<T> genErrorResult(ErrorCode error) {

        return genErrorResult(error.getMessage());
    }

    /**
     * success no message
     * @return
     */
    public static RestResult genSuccessResult() {
        return genSuccessResult(null);
    }
}

統(tǒng)一異常攔截處理：RestExceptionHandler

/**
 * Created by kaenry on 2016/9/20.
 * RestExceptionHandler
 */
@ControllerAdvice(annotations = RestController.class)
public class RestExceptionHandler {

    private static final Logger LOGGER = LoggerFactory.getLogger(RestExceptionHandler.class);

    @ExceptionHandler
    @ResponseBody
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    private <T> RestResult<T> runtimeExceptionHandler(Exception e) {
        LOGGER.error("---------> huge error!", e);
        return RestResultGenerator.genErrorResult(ErrorCode.SERVER_ERROR);
    }

    @ExceptionHandler(MethodArgumentNotValidException.class)
    @ResponseBody
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    private <T> RestResult<T> illegalParamsExceptionHandler(MethodArgumentNotValidException e) {
        LOGGER.error("---------> invalid request!", e);
        return RestResultGenerator.genErrorResult(ErrorCode.ILLEGAL_PARAMS);
    }

}

無(wú)論請(qǐng)求成功或失敗統(tǒng)一返回RestResult，可自由定義，比如加上錯(cuò)誤code或異常的多次處理以及日志啊什么的，代碼都很簡(jiǎn)單，這里就不詳細(xì)介紹了，返回的結(jié)果類似{"result":true,"message":null,"data":{"id":3,"username":"kaenry","password":"jianshu"}}，spring-boot默認(rèn)使用Jackson解析拼裝json，如需要忽略null，加個(gè)注解即可：@JsonInclude(JsonInclude.Include.NON_NULL),fastjson默認(rèn)開(kāi)啟。@Valid注解會(huì)驗(yàn)證屬性，不通過(guò)會(huì)先交給BindingResult，如果沒(méi)有這個(gè)參數(shù)則會(huì)拋出異常MethodArgumentNotValidException，@ExceptionHandler捕捉到異常則會(huì)進(jìn)入illegalParamsExceptionHandler方法返回結(jié)果：

{
  "result": false,
  "message": "request params invalid"
}

測(cè)試RestController修改已有代碼UserRestController:

@RestController
@RequestMapping("/api/users")
public class UserRestController {

    @Autowired
    IUserService userService;

    /**
     * get all user, GET
     * @return
     */
    @RequestMapping(value = "", method = RequestMethod.GET)
    public RestResult<List<User>> all() {
        List<User> all = userService.findAll();
        return RestResultGenerator.genSuccessResult(all);
    }

    /**
     * add single user
     * @param user username, password
     * @return RestResult
     * @throws Exception valid check
     */
    @RequestMapping(value = "", method = RequestMethod.POST)
    public RestResult<User> save(@Valid @RequestBody User user) throws Exception {
        User save = userService.save(user);
        return RestResultGenerator.genSuccessResult(save);
    }

    /**
     * get single user by id, GET /id
     * @param id user id
     * @return RestResult<User>
     * @throws Exception
     */
    @RequestMapping(value = "/{id}", method = RequestMethod.GET)
    public RestResult<User> get(@PathVariable Long id) throws Exception {
        User user = userService.findById(id);
        return RestResultGenerator.genSuccessResult(user);
    }

    /**
     * delete user by id
     * @param id user id
     * @return success
     * @throws Exception
     */
    @RequestMapping(value = "/{id}", method = RequestMethod.DELETE)
    public RestResult delete(@PathVariable Long id) throws Exception {
        userService.delete(id);
        return RestResultGenerator.genSuccessResult();
    }

    /**
     * update user for all props
     * @param id update user id
     * @param newUser new props
     * @return updated User
     * @throws Exception
     */
    @RequestMapping(value = "/{id}", method = RequestMethod.PUT)
    public RestResult<User> updateAll(@PathVariable Long id, @Valid @RequestBody User newUser) throws Exception {
        User user = userService.findById(id);
        // copy all new user props to user except id
        BeanUtils.copyProperties(newUser, user, "id");
        user = userService.save(user);
        return RestResultGenerator.genSuccessResult(user);
    }

    /**
     * update user for some props
     * @param id update user id
     * @param newUser some props
     * @return updated user
     * @throws Exception
     */
    @RequestMapping(value = "/{id}", method = RequestMethod.PATCH)
    public RestResult<User> update(@PathVariable Long id, @Valid @RequestBody User newUser) throws Exception {
        User user = userService.findById(id);
        // copy all new user props to user except null props
        BeanUtils.copyProperties(newUser, user, Utils.getNullPropertyNames(newUser));
        user = userService.save(user);
        return RestResultGenerator.genSuccessResult(user);
    }
}

盡量按照RESTFULL標(biāo)準(zhǔn)書(shū)寫(xiě)的：

1. GET /api/users，獲取全部
2. POST /api/users，新增一個(gè)
3. GET /api/users/:id，獲取單個(gè)
4. DELETE /api/users/:id，刪除單個(gè)
5. PUT /api/users/:id，全量更新
6. PATCH /api/users/:id，部分更新

代碼都很簡(jiǎn)單，注意參數(shù)盡量使用Bean，非特殊情況千萬(wàn)不要使用諸如Map作為接收參數(shù)，圖一時(shí)痛快，飲恨一生?。辉谶@里使用@RequestBody的原因是因?yàn)楝F(xiàn)在的前端（因?yàn)橛辛?code>nodejs）大多都會(huì)采用JSON直傳而不是傳統(tǒng)意義上的form了，對(duì)應(yīng)其實(shí)就是http協(xié)議里的請(qǐng)求頭從application/x-www-form-urlencoded換成了application/json；這里在更新的時(shí)候有個(gè)小技巧，使用BeanUtils復(fù)制需要的屬性，getNullPropertyNames方法是返回對(duì)象里面的為null的屬性，因?yàn)椴恍枰?，具體請(qǐng)看代碼。地址還是那個(gè)地址：https://github.com/kaenry/spring-boot-magneto/releases/tag/v1.8.2。
畢竟不是真實(shí)項(xiàng)目，沒(méi)有寫(xiě)測(cè)試，測(cè)試工具推薦使用PostMan插件，記得先獲取token，隨便上個(gè)圖

新增一個(gè)用戶，kaenry/jianshu