基于Flutter开发一个图片缓存清理插件

dependencies:
  extended_image: ^6.2.0

class judgenetworkimage extends statefulwidget {
  const judgenetworkimage(
    this.url, {
    key? key,
    this.width,
    this.height,
    this.isavatar = false,
    this.fit = boxfit.cover,
    this.borderradius,
    this.shape,
    this.borderwidth = 0.0,
    this.bordercolor,
    this.opacity = 1.0,
    this.scale = 1.0,
    this.maxbytes,
    this.filterquality = filterquality.low,
    this.repeat = imagerepeat.norepeat,
    this.replaceimgplayback = false,
    this.enablememorycache = true,
    this.clearmemorycacheiffailed = true,
    this.clearmemorycachewhendispose = true,
    this.cacherawdata = false,
    this.placeholder,
    this.errorwidget,
    this.loadingwidget,
    this.defaultimagepath,
  }) : super(key: key);

  final string url; // 图片url
  final double? width; // 宽度
  final double? height; // 高度
  final bool isavatar; // 是否为头像
  final boxfit fit; // 适配方式
  final borderradius? borderradius; // 圆角
  final boxshape? shape; // 形状（圆形/矩形）
  final double borderwidth; // 边框宽度
  final color? bordercolor; // 边框颜色
  final double opacity; // 透明度
  final double scale; // 缩放比例
  final int? maxbytes; // 控制图片加载时的字节大小限制
  final filterquality filterquality; // 缩放质量
  final imagerepeat repeat; // 重复方式
  final bool replaceimgplayback; // 更换图片时是否保留旧图
  final bool enablememorycache; // 启用内存缓存
  final bool clearmemorycacheiffailed; // 加载失败时清除缓存
  final bool clearmemorycachewhendispose; // 组件销毁时清除缓存
  final bool cacherawdata; // 缓存原始数据
  final widget? placeholder; // 加载中占位图
  final widget? errorwidget; // 加载失败组件
  final widget? loadingwidget; // 加载中组件
  final string? defaultimagepath; // 默认图片路径

  @override
  state<judgenetworkimage> createstate() => _judgenetworkimagestate();
}

class _judgenetworkimagestate extends state<judgenetworkimage> {
  late string _url;

  @override
  void initstate() {
    super.initstate();
    _url = widget.url;
  }

  @override
  void dispose() {
    super.dispose();
    if (widget.clearmemorycachewhendispose) {
      // 主动清除图片缓存
      if (_url.isnotempty && _url != (widget.defaultimagepath ?? '')) {
        final provider = extendednetworkimageprovider(_url);
        provider.evict();
      }
    }
  }

  @override
  widget build(buildcontext context) {
    widget child = container(
      width: widget.width ?? double.maxfinite,
      height: widget.height ?? double.maxfinite,
      decoration: boxdecoration(
        // 边框部分
        border: widget.borderwidth > 0
            ? border.all(
                color: widget.bordercolor ?? colors.transparent,
                width: widget.borderwidth,
              )
            : null,
      ),
      child: extendedimage.network(
        _url,
        width: widget.width,
        height: widget.height,
        fit: widget.fit,
        scale: widget.scale,
        filterquality: widget.filterquality,
        repeat: widget.repeat,
        gaplessplayback: widget.replaceimgplayback,
        enablememorycache: widget.enablememorycache,
        clearmemorycacheiffailed: widget.clearmemorycacheiffailed,
        clearmemorycachewhendispose: widget.clearmemorycachewhendispose,
        cacherawdata: widget.cacherawdata,
        maxbytes: widget.maxbytes,
        // 应用透时度
        color: widget.opacity < 1.0
            ? colors.white.withopacity(widget.opacity)
            : null,
        colorblendmode: widget.opacity < 1.0 ? blendmode.srcin : null,
        clipbehavior: clip.none,
        // 加载状态回调
        loadstatechanged: (state) {
          return _handleloadstate(state);
        },
      ),
    );

    if (widget.shape == boxshape.circle) {
      return clipoval(
        child: child,
      );
    } else if (widget.borderradius != null) {
      return cliprrect(
        borderradius: widget.borderradius,
        child: child,
      );
    } else {
      return child;
    }
  }

  /// 处理加载状态
  widget _handleloadstate(extendedimagestate state) {
    switch (state.extendedimageloadstate) {
      case loadstate.loading:
        // 加载中显示指示器
        return sizedbox(
          width: widget.width != null ? widget.width! * 0.4 : 42.rpx,
          child: center(
            child: circularprogressindicator(
              valuecolor:
                  const alwaysstoppedanimation<color>(appcolors.success),
              strokewidth: 4.rpx,
            ),
          ),
        );
      case loadstate.completed:
        return state.completedwidget;
      case loadstate.failed:
        // 加载失败 - 显示默认图片并清除缓存
        _clearcacheonerror(state);
        return container(
          color: const color(0xfff2f2f2),
          alignment: alignment.center,
          child: widget.isavatar
              ? image.asset(
                  '${appglobal.imgurl}man_presuppose.png',
                  fit: boxfit.fill,
                )
              : image.asset(
                  '${appglobal.imgurl}not_pic.png',
                  width: widget.width != null ? widget.width! * 0.6 : 64.rpx,
                  fit: boxfit.fitwidth,
                ),
        );
    }
  }

  void _clearcacheonerror(extendedimagestate state) {
    if (widget.clearmemorycacheiffailed && mounted) {
      // 获取图片提供者并清除缓存
      if (state.imageprovider is extendednetworkimageprovider) {
        final provider = state.imageprovider as extendednetworkimageprovider;
        provider.evict();
      }
    }
  }
}