使用Jackson实现Map与Bean互转方式

Jackson Map与Bean互转

在使⽤ java 开发中，通常需要把 Map 转成 Bean，或把 Bean 转成 Map，这就⽤的⼯具类，在此推荐使⽤importcom.fasterxml.jackson.databind.ObjectMapper;包下的ObjectMapper类，⽐ JsonObject 效率⾼

下⾯就列举了⼏种使⽤⽅法

1、pom.xml

com.fasterxml.jackson.core jackson-databind 2.9.6 compile

2、java 代码

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 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); }}

3、Person 类

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 +

\ \ '}'; }}

Jackson-ObjectMapper json字符串、bean、map、list互相转换

1、对象转json字符串

ObjectMapper mapper = new ObjectMapper();User user = new User();

String userJson = mapper.writeValueAsString(user);

2、Map转json字符串

ObjectMapper mapper = new ObjectMapper();Map map = new HashMap();

String json = mapper.writeValueAsString(map);

3、数组list转json字符串

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

String jsonfromArr = mapper.writeValueAsString(uArr);

4、json字符串转对象

ObjectMapper mapper = new ObjectMapper();String expected = \"{\\\"name\\\":\\\"ZhangSan\\\

User user = mapper.readValue(expected, User.class);

5、json字符串转Map

ObjectMapper mapper = new ObjectMapper();String expected = \"{\\\"name\\\":\\\"ZhangSan\\\

Map userMap = mapper.readValue(expected, Map.class);

6、json字符串转对象数组List

ObjectMapper mapper = new ObjectMapper();

String expected = \"[{\\\"name\\\":\\\"Zhangsan\\\

CollectionType listType = mapper.getTypeFactory().constructCollectionType(ArrayList.class, User.class);List userList = mapper.readValue(expected, listType);

7、json字符串转Map数组List>

ObjectMapper mapper = new ObjectMapper();

String expected = \"[{\\\"name\\\":\\\"Zhangsan\\\

CollectionType listType = mapper.getTypeFactory().constructCollectionType(ArrayList.class, Map.class);List> userList = mapper.readValue(expected, listType);

8、jackson默认将对象转换为LinkedHashMap

ObjectMapper mapper = new ObjectMapper();

String expected = \"[{\\\"name\\\":\\\"Zhangsan\\\ArrayList arrayList = mapper.readValue(expected, ArrayList.class);

9、json字符串转对象设置格式

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\\\User user = mapper.readValue(expected, User.class);

10、忽略未知字段

ObjectMapper mapper = new ObjectMapper();//设置忽略未知字段

mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);String expected = \"{\\\"name\\\":\\\"ZhangSan\\\User user = mapper.readValue(expected, User.class);

以上为个⼈经验，希望能给⼤家⼀个参考，也希望⼤家多多⽀持。