对嵌套对象使用对象映射器

Question

我在另一个对象中有一个对象。当我用ObjectMapper询问Servlet.java中的key1值时，我会得到A(key1={key2=[1, 5, 7]})，但我想知道如何分离key2-List值。

字符串输入：{"key1":{"key2":[1,5,7]}}

最终结果：13->calculated from key2 array values (1 + 5 + 7)

基本上，我已经完成了所有操作，但仍然缺少从key2获取值的功能。

A.java

package servlet;
import lombok.Data;
@Data
public class A {
public Object key1;
}

B.java

package servlet;
import lombok.Data;
import java.util.ArrayList;
import java.util.List;
@Data
public class B{
List<Integer> key2 = new ArrayList<>();
}

Servlet.java

package servlet;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.stream.Collectors;
@WebServlet("/validate")
public class Servlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request,
HttpServletResponse response)
throws IOException {
response.getWriter().print("Hello!");
}
@Override
public void doPost(HttpServletRequest request,
HttpServletResponse response) throws IOException {
String input = request.getReader().lines().collect(Collectors.joining("/n"));
A a = new ObjectMapper().readValue(input, new TypeReference<A>() {});
System.out.println(a); // A(key1={key2=[1, 5, 7]})
System.out.println(a.getKey1()); // {key2=[1, 5, 7]}
// Object in object ?
int sum = 0;
String output = new ObjectMapper().writeValueAsString(sum);
response.getWriter().write(output);
} 
}

如何将key2从中分离出来以计算key2数组值的总和？

另一个限制是我不能使用拆分、替换、匹配等

Answer 1

所以基本上，我只需要使用B类而不是Object

package servlet;
import lombok.Data;
@Data
public class A {
public B key1;
}

在servlet中，从A类询问key1和key2，并循环它们

@Override
public void doPost(HttpServletRequest request,
HttpServletResponse response) throws IOException {
String input = request.getReader().lines().collect(Collectors.joining("/n"));
A a = new ObjectMapper().readValue(input, new TypeReference<A>() {});
int sum = 0;
for (Integer b: a.getKey1().getKey2()) {
sum += b;
}
String output = new ObjectMapper().writeValueAsString(sum);
response.getWriter().write(output);
}