public class Group {
private Long id;
private String name;
private List<User> users = new ArrayList<User>();
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<User> getUsers() {
return users;
}
public void setUsers(List<User> users) {
this.users = users;
}
public void addUser(User user) {
users.add(user);
}
}
User.java
public class User {
private Long id;
private String name;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
初始化 Bean
Group group = new Group();
group.setId(0L);
group.setName("admin");
User guestUser = new User();
guestUser.setId(2L);
guestUser.setName("guest");
User rootUser = new User();
rootUser.setId(3L);
rootUser.setName("root");
group.addUser(guestUser);
group.addUser(rootUser);
Group bean = JSON.parseObject(jsonString, Group.class);
2.3. Fastjson 注解
@JSONField
可以配置在属性（setter、getter）和字段（必须是 public field）上。
@JSONField(name="ID")
public int getId() {return id;}
// 配置date序列化和反序列使用yyyyMMdd日期格式
@JSONField(format="yyyyMMdd")
public Date date1;
// 不序列化
@JSONField(serialize=false)
public Date date2;
// 不反序列化
@JSONField(deserialize=false)
public Date date3;
// 按ordinal排序
@JSONField(ordinal = 2)
private int f1;
@JSONField(ordinal = 1)
private int f2;
ObjectMapper mapper = new ObjectMapper();
MyValue value = mapper.readValue(new File("data.json"), MyValue.class);
// or:
value = mapper.readValue(new URL("http://some.com/api/entry.json"), MyValue.class);
// or:
value = mapper.readValue("{\"name\":\"Bob\", \"age\":13}", MyValue.class);
容器的序列化和反序列化
Person p = new Person("Tom", 20);
Person p2 = new Person("Jack", 22);
Person p3 = new Person("Mary", 18);
List<Person> persons = new LinkedList<>();
persons.add(p);
persons.add(p2);
persons.add(p3);
Map<String, List> map = new HashMap<>();
map.put("persons", persons);
String json = null;
try {
json = mapper.writeValueAsString(map);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
3.3. Jackson 注解
@JsonProperty
public class MyBean {
private String _name;
// without annotation, we'd get "theName", but we want "name":
@JsonProperty("name")
public String getTheName() { return _name; }
// note: it is enough to add annotation on just getter OR setter;
// so we can omit it here
public void setTheName(String n) { _name = n; }
}
@JsonIgnoreProperties 和 @JsonIgnore
// means that if we see "foo" or "bar" in JSON, they will be quietly skipped
// regardless of whether POJO has such properties
@JsonIgnoreProperties({ "foo", "bar" })
public class MyBean {
// will not be written as JSON; nor assigned from JSON:
@JsonIgnore
public String internal;
// no annotation, public field is read/written normally
public String external;
@JsonIgnore
public void setCode(int c) { _code = c; }
// note: will also be ignored because setter has annotation!
public int getCode() { return _code; }
}
@JsonCreator
public class CtorBean {
public final String name;
public final int age;
@JsonCreator // constructor can be public, private, whatever
private CtorBean(@JsonProperty("name") String name,
@JsonProperty("age") int age)
{
this.name = name;
this.age = age;
}
}
@JsonPropertyOrder
alphabetic 设为 true 表示，json 字段按自然顺序排列，默认为 false。
@JsonPropertyOrder(alphabetic = true)
public class JacksonAnnotationBean {}
public class VersionedClass {
@Since(1.1) private final String newerField;
@Since(1.0) private final String newField;
private final String field;
public VersionedClass() {
this.newerField = "newer";
this.newField = "new";
this.field = "old";
}
}
VersionedClass versionedObject = new VersionedClass();
Gson gson = new GsonBuilder().setVersion(1.0).create();
String jsonOutput = gson.toJson(versionedObject);
System.out.println(jsonOutput);
System.out.println();
gson = new Gson();
jsonOutput = gson.toJson(versionedObject);
System.out.println(jsonOutput);
@SerializedName
@SerializedName 用于将类成员按照指定名称序列化、反序列化。示例：
private class SomeObject {
@SerializedName("custom_naming") private final String someField;
private final String someOtherField;
public SomeObject(String a, String b) {
this.someField = a;
this.someOtherField = b;
}
}
