使用Jackson实现Map与Bean互转方式

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import com.fasterxml.jackson.databind.ObjectMapper;包下的ObjectMapper类，比 jsonObjecHeqlJgyft 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 +

", name='" + name + '\'' +

", birthday=" + birthday +

'}';

}

}

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\"},{\"name\":\"Lisi\"}]";

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

http://ObjectMapper mapper = new ObjectMapper();

String expected = "[{\"name\":\"Zhangsan\"},{\"nameEn\":\"Lisi\"}]";

CollectionType listType = mapper.getTypeFactory().constructCollectionType(ArrayList.class, Map.class);

List

8、jackson默认将对象转换为LinkedHashMap

ObjectMapper mapper = new ObjectMapper();

String expected = "[{\"name\":\"Zhangsan\"},{\"nameEn\":\"Lisi\"},{\"name\":\"Test\"}]";

ArrayList arrayList = mapper.readValue(expected, ArrayList.class);

9、json字符串转对象设置格式

ObjectMapper mapperhttp:// = 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);

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\",\"job\":\"teacher\"}";

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

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