泛型--->Result返回结果封装

controller的返回结果一般有两种：

    1.Rest API JSON 输出

    2.页面

目的：编写优雅的代码

实现：通过泛型对返回结果进行封装

 

代码如下：

一.控制层

/**
     * 获取用户成功
     * @return
     */
    @RequestMapping("/getUser")
    @ResponseBody
    public Result<User> getUser(@RequestParam("id") int id){
        User user = userService.getUserById(id);
        System.out.println(user.toString());

        return Result.success(user);
    }

返回结果：{"code":0,"message":"SUCCESS","data":{"id":1,"name":"斗战胜佛"}}

/**
     * 获取用户失败
     * @param id
     * @return
     */
    @RequestMapping("/getUserFailed")
    @ResponseBody
    public Result<CodeMsg> getUserFailed(@RequestParam("id") int id){
        User user = userService.getUserById(id);
        System.out.println(user.toString());

        return Result.error(CodeMsg.SERVER_ERROR);
    }

 

返回结果：{"code":500100,"message":"服务端异常","data":null}

二：Result类

public class Result<T> {

    private int code;
    private String message;
    private T data;

    /**
     * 成功时调用
     * @param data
     * @param <T>
     * @return
     */
    public static <T> Result<T> success(T data){
        return new Result<T>(data);
    }

    /**
     * 失败时调用
     * @param codeMsg
     * @param <T>
     * @return
     */
    public static <T> Result error(CodeMsg codeMsg){
        return new Result<T>(codeMsg);
    }

    /**
     * 构造方法私有化，不允许外部new Result
     * @param data
     */
    private Result(T data){
        this.code = 0;
        this.message = "SUCCESS";
        this.data = data;
    }

    /**
     * 构造方法私有化，不允许外部new Result
     * @param codeMsg
     */
    private Result(CodeMsg codeMsg){
        if (null == codeMsg) {
            return;
        }
        this.code = codeMsg.getCode();
        this.message = codeMsg.getMessage();
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }
}

三：CodeMsg类

public class CodeMsg {

     private int code;
     private String message;

    /**
     * //通用模块异常 5001XX
     */
    public static CodeMsg SUCCESS = new CodeMsg(0,"SUCCESS");
     public static CodeMsg SERVER_ERROR = new CodeMsg(500100,"服务端异常");

     //登陆模块异常 5002XX
    //商品模块异常 5003XX
    //订单模块异常 5004XX
    //秒杀模块异常 5005XX


    private CodeMsg(int code, String message) {
        this.code = code;
        this.message = message;
    }

    public int getCode() {
        return code;
    }

    public String getMessage() {
        return message;
    }
}