Gson 转换为 Java Pojo 使值变为空

Question

我必须使用休眠在数据库中持久化 POJO 类社区。我在类 ManageCommunity 中有这个方法：

public void persistCommunity(String name,String domain,String idCustomer){
        Session session = sessionFactory.getCurrentSession();
        session.beginTransaction();
        Community aCommunity=new Community();
        aCommunity.setName(name);
        aCommunity.setDomain(domain);
        aCommunity.setIdCustomer(idCustomer);
       // aCommunity.setIdCommunity(aCommunity.getIdCommunity());
        session.save(aCommunity);
        session.getTransaction().commit();
    }

在带有doPost的servlet上，我调用了这个方法，并传递了邮递员发送的json参数：

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    Gson g = new Gson();
    System.out.println(CommunityHome.getBody(req));
    Community community = g.fromJson(CommunityHome.getBody(req), Community.class);
    System.out.println("Community: "+community);

    HttpSession session = req.getSession(true);
    try {
        ManageCommunity manageCommunity = new ManageCommunity();
        manageCommunity.persistCommunity(community.getName(),community.getDomain(),community.getIdCustomer());

    } catch (Exception e) {

        e.printStackTrace();
    }
}

现在社区的值为空，但如果我看到 getBody(req) 则有 json

这是getBody：

private static String getBody(HttpServletRequest request) throws IOException {

        String body = null;
        StringBuilder stringBuilder = new StringBuilder();
        BufferedReader bufferedReader = null;

        try {
            InputStream inputStream = request.getInputStream();
            if (inputStream != null) {
                bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                char[] charBuffer = new char[128];
                int bytesRead = -1;
                while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
                    stringBuilder.append(charBuffer, 0, bytesRead);
                }
            } else {
                stringBuilder.append("");
            }
        } catch (IOException ex) {
            throw ex;
        } /*finally {
            if (bufferedReader != null) {
                try {
                    bufferedReader.close();
                } catch (IOException ex) {
                    throw ex;
                }
            }
        }*/

        body = stringBuilder.toString();
        return body;
    }

这是 POJO 类：

public class Community{
    public Community(){
        UUID uuid=UUID.randomUUID();
        String random=uuid.toString();
        this.idCommunity=random;
    }



    public String getIdCommunity() {
        return idCommunity;
    }
    public void setIdCommunity(String idCommunity) {
        this.idCommunity = idCommunity;
    }
    public String getIdCustomer() {
        return idCustomer;
    }
    public void setIdCustomer(String idCustomer) {
        this.idCustomer = idCustomer;
    }
    public String getDomain() {
        return domain;
    }
    public void setDomain(String domain) {
        this.domain = domain;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    private String idCommunity;
    private String idCustomer;
    private String domain;
    private String name;

}

CommunityHome.getBody(req)的内容是：

{"idCustomer":"bb05ee35-0494-49e3-9e40-38d5dae10668", "name":"VenditaAbiti2", "domain":"Commerce2"}

Answer 1

把你的 json 改成这样：

{"IdCustomer":"bb05ee35-0494-49e3-9e40-38d5dae10668",
   "Name":"VenditaAbiti2",
   "Domain":"Commerce2"
} 

在这个小例子中得到它的工作：

String json = "{\"IdCustomer\":\"bb05ee35-0494-49e3-9e40-38d5dae10668\",\"Name\":\"VenditaAbiti2\",\"Domain\":\"Commerce2\"}";
        Gson g = new Gson();
        Community community = g.fromJson(json, Community.class);
        System.out.println("Community:" + community.toString());

    }

    class Community {
    @SerializedName("IdCustomer")
    private String idCustomer;

    @SerializedName("Name")
    private String name;

    @SerializedName("Domain")
    private String domain;

    @Override
    public String toString() {
        return "Community [idCustomer=" + idCustomer + ", name=" + name + ", domain=" + domain + "]";
    }

//getter setter

输出：Community:Community [IdCustomer=bb05ee35-0494-49e3-9e40-38d5dae10668, Name=VenditaAbiti2, Domain=Commerce2]

---

EDIT1：

您的 Pojo 变量名称应与您的 json 字符串的键名称匹配。表示 json 键 "IdCustomer" 以大写字母开头。您的变量以小写字母开头。这不能匹配。 但是您可以像我的回答一样注释您的变量。在那里你可以给出 json 键的显式名称。