[Java] 使用Jackson实现Map与Bean互转方式

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.9.6</version>
  <scope>compile</scope>
</dependency>

package com.jin.demo.jackson;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.HashMap;
import java.util.Map;
/**
 * 使用 Jackson工具
 * map to bean
 * bean to map
 *
 * @auther jinsx
 * @date 2019-03-26 16:37
 */
public class JacksonTest {
  private static final ObjectMapper mapper = new ObjectMapper();
  public static void main(String[] args) throws Exception {
    // 测试 将Map转成指定的Bean
    Map<String, Object> map = new HashMap<>();
    map.put("name", "张三");
    Person o = (Person)JacksonTest.mapToBean(map, Person.class);
    System.out.println(o);
    // 测试 将Bean转成Map
    Person person = new Person();
    person.setAge(18);
    Map map1 = JacksonTest.beanToMap(person);
    System.out.println(map1);
  }
  // 将对象转成字符串
  public static String objectToString(Object obj) throws Exception {
    return mapper.writeValueAsString(obj);
  }
  // 将Map转成指定的Bean
  public static Object mapToBean(Map map, Class clazz) throws Exception {
    return mapper.readValue(objectToString(map), clazz);
  }
  // 将Bean转成Map
  public static Map beanToMap(Object obj) throws Exception {
    return mapper.readValue(objectToString(obj), Map.class);
  }
}

package com.jin.demo.jackson;
import java.io.Serializable;
import java.util.Date;
/**
 * @auther jinsx
 * @date 2019-03-26 17:30
 */
public class Person implements Serializable {
  private int age;
  private String name;
  private Date birthday;
  public int getAge() {
    return age;
  }
  public void setAge(int age) {
    this.age = age;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  public Date getBirthday() {
    return birthday;
  }
  public void setBirthday(Date birthday) {
    this.birthday = birthday;
  }
  @Override
  public String toString() {
    return "Person{" +
        "age=" + age +
        ", name='" + name + '\'' +
        ", birthday=" + birthday +
        '}';
  }
}

ObjectMapper mapper = new ObjectMapper();
User user = new User();
String userJson = mapper.writeValueAsString(user);

ObjectMapper mapper = new ObjectMapper();
Map map = new HashMap();
String json = mapper.writeValueAsString(map);

ObjectMapper mapper = new ObjectMapper();
User[] uArr = {user1, user2};
String jsonfromArr = mapper.writeValueAsString(uArr);

ObjectMapper mapper = new ObjectMapper();
String expected = "{"name":"ZhangSan"}";
User user = mapper.readValue(expected, User.class);

ObjectMapper mapper = new ObjectMapper();
String expected = "{"name":"ZhangSan"}";
Map userMap = mapper.readValue(expected, Map.class);

ObjectMapper mapper = new ObjectMapper();
String expected = "[{"name":"Zhangsan"},{"name":"Lisi"}]";
CollectionType listType = mapper.getTypeFactory().constructCollectionType(ArrayList.class, User.class);
List<User> userList = mapper.readValue(expected, listType);

ObjectMapper mapper = new ObjectMapper();
String expected = "[{"name":"Zhangsan"},{"nameEn":"Lisi"}]";
CollectionType listType = mapper.getTypeFactory().constructCollectionType(ArrayList.class, Map.class);
List<Map<String,Object>> userList = mapper.readValue(expected, listType);

ObjectMapper mapper = new ObjectMapper();
String expected = "[{"name":"Zhangsan"},{"nameEn":"Lisi"},{"name":"Test"}]";
ArrayList arrayList = mapper.readValue(expected, ArrayList.class);

ObjectMapper mapper = new ObjectMapper();
//设置date转换格式
SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
mapper.setDateFormat(fmt);
String expected = "{"name":"ZhangSan","bir":"2021-04-15 14:00:00"}";
User user = mapper.readValue(expected, User.class);

ObjectMapper mapper = new ObjectMapper();
//设置忽略未知字段
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
String expected = "{"name":"ZhangSan","job":"teacher"}";
User user = mapper.readValue(expected, User.class);