平时开发中，可能会遇到调用第三方接口返回json串的情形，有时候数据层级结构太复杂时如果要解析为对象，会需要定义多个。其实没必要，fastjson支持解析嵌套类

public class VideoMsg implements Serializable {

    private static final long serialVersionUID = -3018234406294471299L;
    private String touser;
    private String msgtype;
    private Video video;

    class Video {
        private String media_id;
        private String thumb_media_id;
        private String title;
        private String description;

        public String getMedia_id() {
            return media_id;
        }

        public void setMedia_id(String media_id) {
            this.media_id = media_id;
        }

        public String getThumb_media_id() {
            return thumb_media_id;
        }

        public void setThumb_media_id(String thumb_media_id) {
            this.thumb_media_id = thumb_media_id;
        }

        public String getTitle() {
            return title;
        }

        public void setTitle(String title) {
            this.title = title;
        }

        public String getDescription() {
            return description;
        }

        public void setDescription(String description) {
            this.description = description;
        }
    }

    public String getTouser() {
        return touser;
    }

    public void setTouser(String touser) {
        this.touser = touser;
    }

    public String getMsgtype() {
        return msgtype;
    }

    public void setMsgtype(String msgtype) {
        this.msgtype = msgtype;
    }

    public Video getVideo() {
        return video;
    }

    public void setVideo(Video video) {
        this.video = video;
    }
}

测试类:

@Test
    public void testJson2(){
        String json="{\n" +
                "    \"touser\":\"OPENID\",\n" +
                "    \"msgtype\":\"video\",\n" +
                "    \"video\":\n" +
                "    {\n" +
                "      \"media_id\":\"MEDIA_ID\",\n" +
                "      \"thumb_media_id\":\"MEDIA_ID\",\n" +![在这里插入图片描述](https://img-blog.csdn.net/20181025160117100?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5neGlhb3lhbmcw/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70)
                "      \"title\":\"TITLE\",\n" +
                "      \"description\":\"DESCRIPTION\"\n" +
                "    }\n" +
                "}";

        VideoMsg videoMsg = JSON.parseObject(json, VideoMsg.class);
        System.out.println(JSON.toJSONString(videoMsg));
    }

输出：

{"msgtype":"video","touser":"OPENID","video":{"description":"DESCRIPTION","media_id":"MEDIA_ID","thumb_media_id":"MEDIA_ID","title":"TITLE"}}