Spring 之 Converter转换器

Converter主要使用于将前端数据转换为java对应的对象。比如把前端传入的字符串转换为Date类型数据

@Component
public class StringToDateConverter implements Converter {
    public static final Logger logger = LoggerFactory.getLogger(StringToDateConverter.class);
    static SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");

    
    @Override
    public Date convert(String source) {
        Date date = new Date();
        try {
           date =  simpleDateFormat.parse(source);
        } catch (ParseException e) {
            logger.info(source + "转换异常");
            e.printStackTrace();
        }
        return date;
    }
}

Converter

将String类型转换为Date类型，是一个函数接口
主要转换方法在 public Date convert(String source)当中*

不仅可以处理已有的数据类型，还可以处理对应的枚举类型

为了方便，前端在往后端传数据的时候可以值传对应的id,由后端自行处理

枚举

public enum VideoTypeEnum {
    //'电影类型 0 其他 1 动画 2 恐怖 3 爱情 4 动作 5 喜剧',
    ELSE(0,"其他类型"),
    CARTOON(1, "动画"),
    DRACULA(2, "恐怖"),
    LOVE(3, "爱情"),
    ACTION(4, "动作"),
    COMEDY(5, "喜剧");

    private int id;
    private String type;

    VideoTypeEnum() {
    }


    VideoTypeEnum(int i, String s) {
        this.id = i;
        this.type = s;
    }

    public int getId() {
        return id;
    }

    public String getType() {
        return type;
    }

    public static void main(String[] args) {
        for (VideoTypeEnum value : VideoTypeEnum.values()) {
            System.out.println(value.toString() + "  " + value.ordinal());
        }
        System.out.println(VideoTypeEnum.valueOf("ELSE"));
    }

    
    public static VideoTypeEnum getEnumById(int id){
        switch (id){
            case 1:
                return VideoTypeEnum.CARTOON;
            case 2:
                return VideoTypeEnum.DRACULA;
            case 3:
                return VideoTypeEnum.LOVE;
            case 4:
                return VideoTypeEnum.ACTION;
            case 5:
                return VideoTypeEnum.COMEDY;
            default:
                return VideoTypeEnum.ELSE;
        }
    }

    @Override
    public String toString() {
        return "VideoTypeEnum{" +
                "id=" + id +
                ", type='" + type + ''' +
                '}';
    }
}

对应的类型转换器

@Component
public class StringToEnumConverter implements Converter {

    @Override
    public VideoTypeEnum convert(Integer source) {
       return VideoTypeEnum.getEnumById(source);
    }
}