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 JsonObject 效率高
下面就列举了几种使用方法
1、pom.xml
<dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.9.6</version> <scope>compile</scope> </dependency>
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<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); } }
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<User> userList = mapper.readValue(expected, listType);
7、json字符串转Map数组List<Map<String,Object>>
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);
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 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);
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);
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我们。
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