标签：实体类 时间戳 时间格式 演示 value 其他 bsp 使用 etl
ObjectMapper类是Jackson库的主要类。它提供一些功能将转换成Java对象匹配JSON结构，反之亦然
使用Jackson，首先需要相关的jar包。对于使用maven的，需要添加以下依赖：
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.5</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.9.5</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-annotations -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.9.5</version>
</dependency>
ObjectMapper objectMapper = new ObjectMapper();
//序列化的时候序列对象的所有属性
objectMapper.setSerializationInclusion(Include.ALWAYS);
//反序列化的时候如果多了其他属性,不抛出异常
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
//如果是空对象的时候,不抛异常
objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
//取消时间的转化格式,默认是时间戳,可以取消,同时需要设置要表现的时间格式
objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"))
PS：还需要注意，如果ObjectMapper的configure设置FAIL_ON_EMPTY_BEANS为false，那么对应的实体类的属性没有get方法也不会抛出异常，但是这个属性默认的是true，即必须要有get方法，这个需要注意。
public class ObjectMapperTest {
public static void main(String[] args) throws IOException {
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.setSerializationInclusion(JsonInclude.Include.ALWAYS);
objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, true);
Person person = new Person(1, "tom", "123");
String jsonString = objectMapper.writeValueAsString(person);
System.out.println("JsonString: " + jsonString);
Person person1 = objectMapper.readValue(jsonString, Person.class);
System.out.println(person1.toString());
}
}
public static void getListData() {
ObjectMapper objectMapper = new ObjectMapper();
//Java数组转换为JSON数组
Person person = new Person(1, "tom", "123");
Person person1 = new Person(2, "jack", "123445");
List<Person> personList = new ArrayList<>();
personList.add(person);
personList.add(person1);
String jsonString = null;
try {
//Json数组转换为Java数组
jsonString = objectMapper.writeValueAsString(personList);
System.out.println("JsonString List: " + jsonString);
//JavaType
JavaType javaType = objectMapper.getTypeFactory().constructParametricType(List.class, Person.class);
List<Person> list = objectMapper.readValue(jsonString, javaType);
//打印出list中的值
for (Person person2 : list) {
System.out.println(person2.toString());
}
} catch (Exception e) {
e.printStackTrace();
}
}
标签：实体类 时间戳 时间格式 演示 value 其他 bsp 使用 etl
原文地址：https://www.cnblogs.com/yangxiaobai/p/13425061.html
