Java将Json字符串转化为对象（包含list型变量）

在Java中，经常会遇到要将前台传过来的Json字符串转化为对象。一些简单的对象类型，转化起来比较容易。但是，有时候也会遇到嵌套多层list的情况。这种情况，转化时就要麻烦一些。方法如下：

1.先建一个Map<String,Class> 类型的map，其中key为对象中list变量的名称，value是list变量类型的class类。

2.先把json字符串转化为jsonArray，然后遍历这个jsonArray，把每一个值都用toBean方法转化为指定的对象。

转化代码如下：

List<PromoteActivity> promoteActivities = new ArrayList<PromoteActivity>();Map<String, Class> classMap = new HashMap<String, Class>();classMap.put("shares", ActivityCouponShare.class);//转化活动详情数据if(!StringUtils.isBlank(activityVOsStr)) {JSONArray jsonArray = JSONArray.fromObject(activityVOsStr);for(int i=0; i<jsonArray.size(); i++) {JSONObject jsonObject = (JSONObject)jsonArray.get(i);promoteActivities.add((PromoteActivity)JSONObject.toBean(jsonObject,PromoteActivity.class,classMap));}}

其中，classMap是用来存储PromoteActivity对象中list变量的键值对，把所有的list变量的键值对都放在里面即可。PromoteActivity的基本类代码如下：

public class PromoteActivity {    /**     * Table column t_carmktmis_promote_activity.id     */    private Long id;    /**     * Table column t_carmktmis_promote_activity.promote_plan_id     */    private Long promotePlanId;    /**     * Table column t_carmktmis_promote_activity.code     */    private String code;    /**     * Table column t_carmktmis_promote_activity.popup_rate     */    private Float popupRate;    /**     * Table column t_carmktmis_promote_activity.status     */    private Integer status;    /**     * Table column t_carmktmis_promote_activity.share_logo_url     */    private String shareLogoUrl;    /**     * Table column t_carmktmis_promote_activity.share_title     */    private String shareTitle;    /**     * Table column t_carmktmis_promote_activity.share_summary     */    private String shareSummary;    /**     * Table column t_carmktmis_promote_activity.share_o_content     */    private String shareOContent;    /**     * Table column t_carmktmis_promote_activity.share_url     */    private String shareUrl;    /**     * Table column t_carmktmis_promote_activity.update_uid     */    private String updateUid;    /**     * Table column t_carmktmis_promote_activity.update_time     */    private Date updateTime;    /**     * Table column t_carmktmis_promote_activity.remark     */    private String remark;        /**     * 分享话术列表     */    private List<ActivityCouponShare> shares;    /**     * @see PromoteActivity#id     */    public Long getId() {        return id;    }    /**     * @see PromoteActivity#id     */    public void setId(Long id) {        this.id = id;    }    /**     * @see PromoteActivity#promotePlanId     */    public Long getPromotePlanId() {        return promotePlanId;    }    /**     * @see PromoteActivity#promotePlanId     */    public void setPromotePlanId(Long promotePlanId) {        this.promotePlanId = promotePlanId;    }    /**     * @see PromoteActivity#code     */    public String getCode() {        return code;    }    /**     * @see PromoteActivity#code     */    public void setCode(String code) {        this.code = code;    }    /**     * @see PromoteActivity#popupRate     */    public Float getPopupRate() {        return popupRate;    }    /**     * @see PromoteActivity#popupRate     */    public void setPopupRate(Float popupRate) {        this.popupRate = popupRate;    }    /**     * @see PromoteActivity#status     */    public Integer getStatus() {        return status;    }    /**     * @see PromoteActivity#status     */    public void setStatus(Integer status) {        this.status = status;    }    /**     * @see PromoteActivity#shareLogoUrl     */    public String getShareLogoUrl() {        return shareLogoUrl;    }    /**     * @see PromoteActivity#shareLogoUrl     */    public void setShareLogoUrl(String shareLogoUrl) {        this.shareLogoUrl = shareLogoUrl;    }    /**     * @see PromoteActivity#shareTitle     */    public String getShareTitle() {        return shareTitle;    }    /**     * @see PromoteActivity#shareTitle     */    public void setShareTitle(String shareTitle) {        this.shareTitle = shareTitle;    }    /**     * @see PromoteActivity#shareSummary     */    public String getShareSummary() {        return shareSummary;    }    /**     * @see PromoteActivity#shareSummary     */    public void setShareSummary(String shareSummary) {        this.shareSummary = shareSummary;    }    /**     * @see PromoteActivity#shareOContent     */    public String getShareOContent() {        return shareOContent;    }    /**     * @see PromoteActivity#shareOContent     */    public void setShareOContent(String shareOContent) {        this.shareOContent = shareOContent;    }    /**     * @see PromoteActivity#shareUrl     */    public String getShareUrl() {        return shareUrl;    }    /**     * @see PromoteActivity#shareUrl     */    public void setShareUrl(String shareUrl) {        this.shareUrl = shareUrl;    }    /**     * @see PromoteActivity#updateUid     */    public String getUpdateUid() {        return updateUid;    }    /**     * @see PromoteActivity#updateUid     */    public void setUpdateUid(String updateUid) {        this.updateUid = updateUid;    }    /**     * @see PromoteActivity#updateTime     */    public Date getUpdateTime() {        return updateTime;    }    /**     * @see PromoteActivity#updateTime     */    public void setUpdateTime(Date updateTime) {        this.updateTime = updateTime;    }    /**     * @see PromoteActivity#remark     */    public String getRemark() {        return remark;    }    /**     * @see PromoteActivity#remark     */    public void setRemark(String remark) {        this.remark = remark;    }public List<ActivityCouponShare> getShares() {return shares;}public void setShares(List<ActivityCouponShare> shares) {this.shares = shares;}}

ActivityCouponShare基本类型的代码如下

public class ActivityCouponShare {    /**     * Table column t_carmktmis_activity_coupon_share.id     */    private Long id;    /**     * Table column t_carmktmis_activity_coupon_share.promote_activity_id     */    private Long promoteActivityId;    /**     * Table column t_carmktmis_activity_coupon_share.coupon_cate_id     */    private Long couponCateId;    /**     * Table column t_carmktmis_activity_coupon_share.share_content     */    private String shareContent;        /**     * 代金券面值     */    private Integer couponValue;    /**     * @see ActivityCouponShare#id     */    public Long getId() {        return id;    }    /**     * @see ActivityCouponShare#id     */    public void setId(Long id) {        this.id = id;    }    /**     * @see ActivityCouponShare#promoteActivityId     */    public Long getPromoteActivityId() {        return promoteActivityId;    }    /**     * @see ActivityCouponShare#promoteActivityId     */    public void setPromoteActivityId(Long promoteActivityId) {        this.promoteActivityId = promoteActivityId;    }    /**     * @see ActivityCouponShare#couponCateId     */    public Long getCouponCateId() {        return couponCateId;    }    /**     * @see ActivityCouponShare#couponCateId     */    public void setCouponCateId(Long couponCateId) {        this.couponCateId = couponCateId;    }    /**     * @see ActivityCouponShare#shareContent     */    public String getShareContent() {        return shareContent;    }    /**     * @see ActivityCouponShare#shareContent     */    public void setShareContent(String shareContent) {        this.shareContent = shareContent;    }public Integer getCouponValue() {return couponValue;}public void setCouponValue(Integer couponValue) {this.couponValue = couponValue;}