Jackson第一篇

基础准备

Spring中已引入jackson相关依赖，无须在pom中再引入相关依赖，若再引入相关依赖，则会报错创建bean异常。

使用

写一个PlayerStar的实体类，实体类主要体现篮球明星的名字、年龄、业余爱好、朋友、年收入等信息，为了尽可能地演示Jackson的序列化与反序列化功能，将数组、List、Map都融合到这个类里面。并通过getInstance初始化篮球明星Jordan这个对象。

@Data public class PlayerStar { private String name; private Integer age; private String[] hobbies; //业余爱好,数组 private List<String> friends; // 朋友 private Map<String, BigDecimal> salary; //年收入 Map //初始化一个对象用于测试 public static PlayerStar getInstance(){ PlayerStar playerStar = new PlayerStar(); playerStar.setName("乔丹"); playerStar.setAge(45); playerStar.setHobbies(new String[]{"高尔夫球", "棒球"}); Map<String, BigDecimal> salary = new HashMap<String, BigDecimal>() {{ put("2000", new BigDecimal(10000000)); put("2010", new BigDecimal(62000000)); put("2020", new BigDecimal(112400000)); }}; playerStar.setSalary(salary); playerStar.setFriends(Arrays.asList("kobe", "curry", "james")); return playerStar; } }

序列化方法

@Test void testObject2JSON() throws IOException { //获取对象实例 PlayerStar player = PlayerStar.getInstance(); //ObjectMapper作为Jackson的API工具类存在 ObjectMapper mapper = new ObjectMapper(); //将player对象以JSON格式进行序列化，并将序列化结果写入文件 mapper.writeValue(new File("d:\data\jackson\player.json"), player); //将player对象以JSON格式进行序列化为String对象 String jsonString = mapper.writeValueAsString(player); System.out.println(jsonString); //将player对象以JSON格式进行序列化为String对象(格式美化) String jsonInString2 = mapper.writerWithDefaultPrettyPrinter() .writeValueAsString(player); System.out.println(jsonInString2); }

反序列化方法

@Test void testJSON2Object() throws IOException { ObjectMapper mapper = new ObjectMapper(); //从文件中读取JSON字符串，反序列化为java对象 PlayerStar player = mapper.readValue(new File("d:\data\jackson\player.json"), PlayerStar.class); System.out.println(player); //将JSON字符串反序列化为java对象 String jsonInString = "{\"name\":\"乔丹\",\"age\":45,\"hobbies\":[\"高尔夫球\",\"棒球\"]}"; PlayerStar jordan = mapper.readValue(jsonInString, PlayerStar.class); System.out.println(jordan); }

字段重命名

可以使用 @JsonProperty来影响序列化和反序列化对象属性的重命名。

@Data public class PlayerStar { @JsonProperty("playerName") private String name; //将属性name序列化为playerName，同时影响反序列化 String jsonInString = "{\"name\":\"乔丹\",\"age\":45,\"hobbies\":[\"高尔夫球\",\"棒球\"]}"; PlayerStar jordan = mapper.readValue(jsonInString, PlayerStar.class);