Question

我有一个日期如下的json文件：

def neural_network(num_hid, epochs, 
                  learning_rate, X, Y):
    #num_hid - number of neurons in the hidden layer
    #X - dataX - shape (10000, 784)
    #Y - labels - shape (10000, 10)

    #inicialization
    W1 = np.random.randn(784, num_hid) * 0.01
    W2 = np.random.randn(num_hid, 10) * 0.01
    b1 = np.zeros((1, num_hid))
    b2 = np.zeros((1, 10))
    correct = 0

    for x in range(1, epochs+1):
        #feedforward
        Z1 = np.dot(X, W1) + b1
        A1 = tanh(Z1)
        Z2 = np.dot(A1, W2) + b2
        A2 = softmax(Z2)


        ###############################################################################START
        m = X.shape[1] #-> 784
        loss = - np.sum((Y * np.log(A2)), axis=0, keepdims=True)
        cost = np.sum(loss, axis=1) / m

        #backpropagation
        dZ2 = A2 - Y
        dW2 = (1/m)*np.dot(A1.T, dZ2)
        db2 = (1/m)*np.sum(dZ2, axis = 1, keepdims = True)
        dZ1 = np.multiply(np.dot(dZ2, W2.T), 1 - np.power(A1, 2))
        dW1 = (1/m)*np.dot(X.T, dZ1)
        db1 = (1/m)*np.sum(dZ1, axis = 1, keepdims = True)
        ###############################################################################STOP


        #parameters update - gradient descent
        W1 = W1 - dW1*learning_rate
        b1 = b1 - db1*learning_rate
        W2 = W2 - dW2*learning_rate
        b2 = b2 - db2*learning_rate

        correct = 0
        for i in range(np.shape(Y)[0]):
            guess = np.argmax(A2[i, :])
            ans = np.argmax(Y[i, :])
#             print(str(x) + " " + str(i) + ". " +"guess: ", guess, "| ans: ", ans)
            if guess == ans:
                correct = correct + 1

#         correct = np.sum(np.argmax(A2,axis=1) == np.argmax(Y,axis=1))
#         print(correct)
        accuracy = (correct/np.shape(Y)[0]) * 100
        print(accuracy)

我在课堂上使用

{
...
  "dob":"20001010",
  "registerdate":"20001010121212",
...
}

然后在我的测试中，我使用Gson转换文件

public class User implements Serializable {
... some other
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyyMMdd
    public java.util.Date dob; // this works

    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyyMMddHHmmss")
    public java.util.Date registerdate;
}

但是当运行时，我得到：

User user = new Gson().fromJson("user.json", User.class);

我害怕：yyyyMMddHHmmss或YYYYMMddHHmmss或YYYYMMDDHHmmss相同的结果

pom：

com.google.gson.JsonSyntaxException: 20001010121212

Answer 1

如果您使用的是GSON，则需要解析日期，例如

import java.util.Date;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class GSONExample {

    private static String json = "{\r\n" + "  \"dob\":\"20001010121212\"\r\n" + "}";

    public static void main(String[] args) {
        Gson gson = new GsonBuilder().setDateFormat("yyyyMMddHHmmss").create();
        ItemDob itemDob = gson.fromJson(json, ItemDob.class);
        System.out.println(itemDob.getDob());
    }

}

class ItemDob {
    private Date dob;

    public Date getDob() {
        return dob;
    }

    public void setDob(Date dob) {
        this.dob = dob;
    }
}

输出

IST 2000年10月10日星期二12:12:12

编辑如果要使用注释指定日期格式，请使用jackson。例如，

import java.util.Date;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonExample {

    private static String json = "{\r\n" + 
            "  \"dob\": \"20001010121212\"\r\n" + 
            "}";

    public static void main(String[] args) throws JsonMappingException, JsonProcessingException {
        ItemDob itemDob = new ObjectMapper().readValue(json, ItemDob.class);
        System.out.println(itemDob.getDob());
    }

}

class ItemDob {
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyyMMddHHmmss")
    private Date dob;

    public Date getDob() {
        return dob;
    }

    public void setDob(Date dob) {
        this.dob = dob;
    }
}

输出：

IST 2000年10月10日17:42:12

Answer 2

基本上 com.google.gson.Gson 无法识别注释 com.fasterxml.jackson.annotation.JsonFormat （两个不同的库）

这是仅使用来自fasterxml lib的ObjectMapper的另一种解决方案

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.Serializable;
import java.util.Date;

public class DemoApplication {
    public static void main(String[] args) throws JsonProcessingException {
        String json = "{\"dob\":\"20001010121212\"}";
        ObjectMapper objectMapper = new ObjectMapper();
        User user = objectMapper.readValue(json, User.class);
        System.out.println(user.dob);
    }
}

class User implements Serializable {
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyyMMddHHmmss")
    public Date dob;
}

json反序列化因有效格式而失败

2 个答案: