ObjectMapper mapper = new XmlMapper();
System.out.println(mapper.writeValueAsString(person));
但是输出为紧凑模式：
<Person><name>Hello world</name><age>12</age></Person>
2.目的：美化过的输出
有时希望能够美化输出，更方便阅读和理解，如：
<Person>
<name>Hello world</name>
<age>12</age>
</Person>
方式1.使用：writerWithDefaultPrettyPrinter
ObjectMapper mapper = new XmlMapper();
System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(person));
mapper.enable(SerializationFeature.INDENT_OUTPUT);
方式2.使用：SerializationFeature.INDENT_OUTPUT
ObjectMapper mapper = new XmlMapper();
mapper.enable(SerializationFeature.INDENT_OUTPUT);
mapper.writeValueAsString(person);
3.序列化为json
序列化为json时，操作基本一致，只需要使用ObjectMapper替代XmlMapper。如：
Person person = new Person();
//设置person属性
ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.writeValueAsString(person));
激活美化的方式，同样可以是2.1和2.2介绍的方式。
4.包依赖
序列化为xml依赖：
jackson-databind
jackson-core
jackson-dataformat-xml
序列化为json依赖:
jackson-databind
jackson-core
<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-xml</artifactId>
<version>2.8.2</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.8.2</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.8.2</version>
</dependency>
