Spring Boot内置Jackson库的实战

<!-- Jackson核心依赖（非Web项目需引入） -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.15.3</version> <!-- 版本与Spring Boot兼容即可 -->
</dependency>
<!-- 支持CSV格式所需扩展依赖 -->
<dependency>
    <groupId>com.fasterxml.jackson.dataformat</groupId>
    <artifactId>jackson-dataformat-csv</artifactId>
</dependency>
<!-- 支持XML格式所需扩展依赖 -->
<dependency>
    <groupId>com.fasterxml.jackson.dataformat</groupId>
    <artifactId>jackson-dataformat-xml</artifactId>
</dependency>

import lombok.Data;
import java.util.Date;
//  lombok注解，简化getter/setter/构造器
@Data
public class User {
    private Long id;                // 用户ID
    private String username;        // 用户名
    private Integer age;            // 年龄
    private String email;           // 邮箱
    private Date createTime;        // 创建时间
}
// 测试数据准备
public class TestData {
    public static User getTestUser() {
        User user = new User();
        user.setId(1L);
        user.setUsername("jackson_demo");
        user.setAge(25);
        user.setEmail("demo@example.com");
        user.setCreateTime(new Date());
        return user;
    }
}

import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
public class JacksonJsonTest {
    // 注入Spring Boot自动配置的ObjectMapper
    @Autowired
    private ObjectMapper objectMapper;

    // 基础序列化：POJO转JSON字符串
    @Test
    public void testPojoToJson() throws Exception {
        User user = TestData.getTestUser();
        // 序列化：Object → JSON字符串
        String jsonStr = objectMapper.writeValueAsString(user);
        System.out.println("POJO转JSON结果：\n" + jsonStr);
    }
}

{
  "id":1,
  "username":"jackson_demo",
  "age":25,
  "email":"demo@example.com",
  "createTime":1699999999999
}

// 基础反序列化：JSON字符串转POJO
@Test
public void testJsonToPojo() throws Exception {
    String jsonStr = "{"id":1,"username":"jackson_demo","age":25,"email":"demo@example.com","createTime":1699999999999}";
    // 反序列化：JSON → Object
    User user = objectMapper.readValue(jsonStr, User.class);
    System.out.println("JSON转POJO结果：\n" + user);
}

// 定制化配置：日期格式化、空值过滤、字段命名策略
@Test
public void testCustomJsonConfig() throws Exception {
    User user = TestData.getTestUser();
    user.setEmail(null); // 模拟空值字段

    // 定制ObjectMapper配置
    ObjectMapper customObjectMapper = new ObjectMapper()
            // 日期格式化：转为yyyy-MM-dd HH:mm:ss
            .setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"))
            // 忽略空值字段
            .setSerializationInclusion(JsonInclude.Include.NON_NULL)
            // 字段命名策略：驼峰转下划线（如createTime → create_time）
            .setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);

    String jsonStr = customObjectMapper.writeValueAsString(user);
    System.out.println("定制化JSON结果：\n" + jsonStr);
}

{
  "id":1,
  "username":"jackson_demo",
  "age":25,
  "create_time":"2025-12-24 23:59:59"
}

// CSV文件转POJO列表
@Test
public void testCsvToPojoList() throws Exception {
    // 定义CSV Schema（指定表头，用于映射POJO字段）
    CsvSchema csvSchema = csvMapper.schemaFor(User.class)
            .withHeader() // 跳过表头行（读取时忽略第一行）
            .withColumnSeparator(',');

    // 反序列化CSV文件到POJO列表
    List<User> userList = csvMapper.readerFor(User.class)
            .with(csvSchema)
            .readValues(new File("user.csv"))
            .readAll();

    System.out.println("CSV转POJO列表结果：\n" + userList);
}

// CSV文件转POJO列表
@Test
public void testCsvToPojoList() throws Exception {
    // 定义CSV Schema（指定表头，用于映射POJO字段）
    CsvSchema csvSchema = csvMapper.schemaFor(User.class)
            .withHeader() // 跳过表头行（读取时忽略第一行）
            .withColumnSeparator(',');

    // 反序列化CSV文件到POJO列表
    List<User> userList = csvMapper.readerFor(User.class)
            .with(csvSchema)
            .readValues(new File("user.csv"))
            .readAll();

    System.out.println("CSV转POJO列表结果：\n" + userList);
}

import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import org.junit.Test;

import java.io.File;

public class JacksonXmlTest {
    private final XmlMapper xmlMapper = new XmlMapper();

    // POJO转XML字符串（带根节点）
    @Test
    public void testPojoToXml() throws Exception {
        User user = TestData.getTestUser();

        // 定制XML配置：日期格式化
        xmlMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));

        // 序列化到XML字符串
        String xmlStr = xmlMapper.writerWithDefaultPrettyPrinter().writeValueAsString(user);
        System.out.println("POJO转XML结果：\n" + xmlStr);

        // 序列化到XML文件
        xmlMapper.writerWithDefaultPrettyPrinter()
                .writeValue(new File("user.xml"), user);
    }
}

<User>
  <id>1</id>
  <username>jackson_demo</username>
  <age>25</age>
  <email>demo@example.com</email>
  <createTime>2025-12-24 23:59:59</createTime>
</User>

// XML字符串转POJO
@Test
public void testXmlToPojo() throws Exception {
    String xmlStr = "<User>" +
            "<id>1</id>" +
            "<username>jackson_demo</username>" +
            "<age>25</age>" +
            "<email>demo@example.com</email>" +
            "<createTime>2025-12-24 23:59:59</createTime>" +
            "</User>";
    // 反序列化XML到POJO
    User user = xmlMapper.readValue(xmlStr, User.class);
    System.out.println("XML转POJO结果：\n" + user);
}