如何使用Java中的排除过滤器将一个bean转换为JSON对象？

可以使用JsonConfig类来配置序列化过程。我们可以使用JsonConfig的setJsonPropertyFilter()方法来设置在序列化为JSON时的属性过滤器。我们需要通过重写PropertyFilter接口的apply()方法来实现一个自定义的PropertyFilter类。如果属性将被过滤掉，则返回true，否则返回false。

md2card

Markdown转知识卡片

下载

语法

public void setJsonPropertyFilter(PropertyFilter jsonPropertyFilter)

Example

import net.sf.json.JSONObject;
import net.sf.json.JsonConfig;
import net.sf.json.util.PropertyFilter;
public class ConvertBeanToJsonExcludeFilterTest {
   public static void main(String[] args) {
      Student student = new Student("Sai", "Chaitanya", 20, "Hyderabad");
      JsonConfig jsonConfig = new JsonConfig();
      jsonConfig.setJsonPropertyFilter(new CustomPropertyFilter());

      JSONObject jsonObj = JSONObject.fromObject(student, jsonConfig);
      System.out.println(jsonObj.toString(3)); //pretty print JSON
   }
   public static class Student {
      private String firstName, lastName, address;
      public int age;
      public Student(String firstName, String lastName, int age, String address) {
         super();
         this.firstName = firstName;
         this.lastName = lastName;
         this.age = age;
         this.address = address;
      }
      public String getFirstName() {
         return firstName;
      }
      public String getLastName() {
         return lastName;
      }
      public int getAge() {
         return age;
      }
      public String getAddress() {
         return address;
      }
   }
}
// CustomPropertyFilter class
class CustomPropertyFilter implements PropertyFilter {
   @Override
   public boolean apply(Object source, String name, Object value) {
      if(Number.class.isAssignableFrom(value.getClass()) ||        String.class.isAssignableFrom(value.getClass())) {
         return false;
      }
      return true;
   }
}

输出

{
  "firstName": "Sai",
  "lastName": "Chaitanya",
  "address": "Hyderabad",
  "age": 20
}