1. 定义统一返回结果形式

{
	"success": 布尔, //响应是否成功
	"code": 数字, //响应码
	"message": 字符串, //返回消息
	"data": HashMap //返回数据，放在键值对中
}

2.创建返回码（定义枚举类）

@Getter
public enum ResultCodeEnum {

	SUCCESS(true, 20000,"成功"),
	UNKNOWN_REASON(false, 20001, "未知错误"),
	BAD_SQL_GRAMMAR(false, 21001, "sql语法错误"),
	JSON_PARSE_ERROR(false, 21002, "json解析异常"),
	PARAM_ERROR(false, 21003, "参数不正确");
	
	private Boolean success;
	private Integer code;
	private String message;
	
	private ResultCodeEnum(Boolean success, Integer code, String message) {
		this.success = success;
		this.code = code;
		this.message = message;
	}
}

3.创建返回结果类

@ApiModel(value = "全局统一返回结果")
public class R {

	@ApiModelProperty(value = "是否成功")
	private Boolean success;
	
	@ApiModelProperty(value = "返回码")
	private Integer code;
	
	@ApiModelProperty(value = "返回消息")
	private String message;
	
	@ApiModelProperty(value = "返回数据")
	private Map<String, Object> data = new HashMap<String, Object>();
	
	private R(){
	}
	
	public static R ok(){
		R r = new R();
		r.setSuccess(ResultCodeEnum.SUCCESS.getSuccess());
		r.setCode(ResultCodeEnum.SUCCESS.getCode());
		r.setMessage(ResultCodeEnum.SUCCESS.getMessage());
		return r;
	}
	
	public static R error(){
		R r = new R();
		r.setSuccess(ResultCodeEnum.UNKNOWN_REASON.getSuccess());
		r.setCode(ResultCodeEnum.UNKNOWN_REASON.getCode());
		r.setMessage(ResultCodeEnum.UNKNOWN_REASON.getMessage());
		return r;
	}
	
	public static R setResult(ResultCodeEnum resultCodeEnum){
		R r = new R();
		r.setSuccess(resultCodeEnum.getSuccess());
		r.setCode(resultCodeEnum.getCode());
		r.setMessage(resultCodeEnum.getMessage());
		return r;
	}
	

	public R success(Boolean success){
		this.setSuccess(success);
		return this;
	}
	
	public R message(String message){
		this.setMessage(message);
		return this;
	}
	
	public R code(Integer code){
		this.setCode(code);
		return this;
	}
	
	public R data(String key, Object value){
		this.data.put(key, value);
		return this;
	}
	
	public R data(Map<String, Object> map){
		this.setData(map);
		return this;
	}
}

4.Controller返回统一结果

@ApiOperation(value = "所有产品列表")
@GetMapping
public R list(){
	List<Product> list = productService.list(null);
	return R.ok().data("items",list);
}

@ApiOperation(value = "根据ID删除产品")
@DeleteMapping("{id}")
public R removeById(@ApiParam(name = "id", value = "产品ID", required = true)
					@PathVariable int id){
	productService.removeById(id);
	return R.ok();
}