Mybatis-plus分页返回统一结果集

Dear 丶 2023-09-27 12:34 163阅读 0赞

### 1.分页起作用，需要配置拦截器 ###

@Configuration
    public class MybatisPlusConfig {
        /**
         * 新的分页插件,一缓和二缓遵循mybatis的规则,需要设置 MybatisConfiguration#useDeprecatedExecutor = false 避免缓存出现问题(该属性会在旧插件移除后一同移除)
         */
        @Bean
        public MybatisPlusInterceptor mybatisPlusInterceptor() {
            MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
            interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
            return interceptor;
        }

### 2.分页的原理 ###

Mybatis-plus分页插件使用的是**IPage进行分页**。IPage内部**原理是基于拦截器**，拦截的是**方法以及方法中的参数**。【判断是否是查询操作，如果是**查询操作，才会进入分页**的处理逻辑】。 进入分页逻辑处理后，拦截器会通过**反射获取该方法的参数进行判断是否存在IPage对象的实现类**。如果**不存在则不进行分页，存在则将该参数赋值给IPage对象**，（上述已说IPage分页，故参数给IPage对象）然后进行拼接sql的处理完成分页操作。

### 3.统一结果集 ###

#### 3.1返回码定义类 提供两种任选一种 ####

**常量类模式**

public class ResultCode {
        /**成功 **/
        public final static int OK = 20000;
        /** 失败 **/
        public final static int ERROR = 20001;
        /**用户名或密码错误 **/
        public final static int LOGIN_ERROR = 20002;
        /** 权限不足**/
        public final static int ACCESS_ERROR = 20003;
        /** 远程调用失败**/
        public final static int REMOTE_ERROR = 20004;
        /** 重复操作**/
        public final static int REPEAT_ERROR = 20005;
    }

**枚举类模式**

public enum ResponseCodeEnum {
        REQUEST_OK(200, "请求成功！"),
        OPERATE_FAIL(101, "操作失败"),
        BAD_REQUEST(400, "错误请求"),
        ERROR(500, "系统异常"),
        UNAUTHORIZED(401, "未授权"),
        FORBIDDEN(403, "访问受限，授权过期"),
        NOT_FOUND(404, "资源，服务未找到"),
        NO_USER_LOGIN(1000, "用户没有登录或登录超时失效"),
        AUTHORITY_NOT_ALLOW(1002, "权限不匹配"),
        PARAM_ENUM_TRANS_EXP(2000, "传入的参数无法找到系统对应的配置值"),
        SERIOUS_PARAM_EMPTY(2001, "必输参数为空"),
        PARAM_IS_INVALID(2002, "参数无效"),
        SYSTEM_ERROR(3001, "系统异常，请稍后重试"),
        GLOBAL_EXCEPTION(6666, "抱歉，系统开小差了");
    
        /** 编码 */
        private Integer code;
    
        private String message;
    
        ResponseCodeEnum(Integer code, String message) {
            this.code = code;
            this.message = message;
        }

#### 3.2结果集类 含有处理分页+不含处理分页（返回结果直接放入data中） ####

@Data
    @ApiModel(value = "全局统一返回结果")
    public class R implements Serializable {
        public final static String OK_MSG = "请求成功";
        public final static String FAIL_MSG = "请求失败";
        @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 Object data;
        @ApiModelProperty(value = "总条数")
        private Long total;
        @ApiModelProperty(value = "分页信息")
        private PageInfo pageInfo;
        @Data
        public static class PageInfo {
    
            @ApiModelProperty("当前页")
            protected int currentPage;
            @ApiModelProperty("页大小")
            protected int pageSize;
            @ApiModelProperty("总记录数")
            protected long totalCount;
            @ApiModelProperty("总页数")
            protected long totalPage;
    
            public PageInfo() {
            }
    
            @ConstructorProperties({"currentPage", "pageSize", "totalCount", "totalPage"})
            public PageInfo(int currentPage, int pageSize, long totalCount, long totalPage) {
                this.currentPage = currentPage;
                this.pageSize = pageSize;
                this.totalCount = totalCount;
                this.totalPage = totalPage;
            }
        }
        private R(){}
        private R(int code, String msg, Object data) {
            this.code = code;
            this.message = msg;
    //代码重要点 此处区分分页结果或是 普通结果
            if (data instanceof Page<?>) {
                Page<?> page = (Page<?>) data;
                this.total = page.getTotal();
                this.data = page.getRecords();
                this.pageInfo = new PageInfo((int)page.getCurrent(), (int)page.getSize(), page.getTotal(), page.getPages());
            } else {
                this.data = data;
            }
        }
    
        public static R ok(){
            R r = new R();
            r.setSuccess(true);
            r.setCode(ResultCode.OK);
            r.setMessage("成功");
            return r;
        }
        public static R ok(Object data) {
            return new R(ResultCode.OK, OK_MSG, data);
        }
        public static R ok(String msg, Object data) {
            return new R(ResultCode.OK, msg, data);
        }
        public static R error(){
            R r = new R();
            r.setSuccess(false);
            r.setCode(ResultCode.ERROR);
            r.setMessage("失败");
            return r;
        }
        public static R error(String msg) {
            return new R(ResultCode.ERROR, msg, null);
        }
        public static R error(int errorCode, String msg) {
            return new R(errorCode, msg, null);
        }
        public R message(String message){
            this.setMessage(message);
            return this;
        }
        public R code(Integer code){
            this.setCode(code);
            return this;
        }
        public R data(Object data){
            this.setData(data);
            return this;
        }
    
    }

public class ResponseResult<T> {
        // 结果状态码
        private Integer code;
        // 响应信息
        private String message;
        // 响应数据
        private T data;
    //方法名 ok可改为success 看个人习惯
        public static <T> ResponseResult<T> ok(T data) {
            return new ResponseResult<>(codeEnum.REQUEST_OK.getCode(), codeEnum.REQUEST_OK.getMessage(), data);
        }
    
        public static <T> ResponseResult<T> fail(T data, Integer code, String msg) {
            return new ResponseResult<>(code, msg, data);
        }
    
        public static <T> ResponseResult<T> fail(T data, codeEnum e) {
            return new ResponseResult<>(e.getCode(), e.getMessage(), data);
        }
        public static <T> ResponseResult<T> fail(codeEnum e) {
            return new ResponseResult<>(e.getCode(), e.getMessage(), null);
        }