jackson是springboot中集成的序列化方式，是默认的json序列化方式，当然你可以使用其它的序列化工具代替它，不过今天我们还是说一下它，使用jackson进行序列化一个类，然后再把它的JSON字符反序列化为它的接口对象。

现实

这种方式默认是不行的，因为接口不能被自动实例化

使用redisTelmplete时，如果使用objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);这种试序列化，由于会把实例类型写到时 JSON里，所以也不能反序列化为接口

几个序列化方式

一 序列化为具体类型，无法反序列化接口，即你用什么类型序列化的，就用什么类型反序列化，它经常与redis的序列化Jackson2JsonRedisSerializer一起使用。

ObjectMapper om = new ObjectMapper();

om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);

om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);

User user = new User();

user.setUsername("lind");

user.setEmail("zzl@sina.com");

String msg = om.writeValueAsString(user);

结果

["com.lind.common.JacksonTest$User",{"username":"lind","email":"zzl@sina.com","authorities":null}]

二 序列化为字符串，主要好处是与类型无关，只要字段可以配置上，就可以反序列化，并且在自定义序列化器定义之后，还可以对接口类型进行反序列化，可以说更加方便。

定义一个序列化器

public static class DefaultResourceUserSerializer extends JsonDeserializer {

@Override

public DefaultResourceUser deserialize(JsonParser jsonParser, DeserializationContext deserializationContext)

throws IOException {

ObjectCodec oc = jsonParser.getCodec();

JsonNode node = oc.readTree(jsonParser);

DefaultResourceUser userAccountAuthentication = new DefaultResourceUser() {

@Override

public String getUsername() {

return node.get("username").asText();

}

@Override

public String getEmail() {

return node.get("email").asText();

}

@Override

public Collection extends GrantedAuthority> getAuthorities() {

List simpleGrantedAuthorities = new ArrayList<>();

Iterator elements = node.get("authorities").elements();

while (elements.hasNext()) {

JsonNode next = elements.next();

JsonNode authority = next.get("authority");

simpleGrantedAuthorities.add(new SimpleGrantedAuthority(authority.asText()));

}

return simpleGrantedAuthorities;

}

};

return userAccountAuthentication;

}

在接口上使用它

``

@JsonDeserialize(using = DefaultResourceUserSerializer.class)

public interface DefaultResourceUser {

String getUsername();

String getEmail();

Collection extends GrantedAuthority> getAuthorities();

}

代码展现了反序列化一个json字符串

json

{

"id": "347214418355949568",

"username": "admin",

"password": "{bcrypt}$2a$10$tVrm4VjC9BXF8PStUASZkOJCOm7mKR4ZVDHau.Ug/tm6ZEXEsHhcC",

"nickName": "测试",

"mobile": "",

"email": "",

"address": "北京",

"street": "",

"sex": 0,

"passStrength": "",

"avatar": "",

"type": 0,

"status": 0,

"description": "",

"departmentId": "",

"departmentTitle": null,

"resourcePermissions": [{

"id": "348193374957735936",

"title": "系统管理",

"path": "",

"type": 0,

"parentId": "",

"parent": null,

"sons": null

}, {

"id": "348193687223668737",

"title": "用户管理",

"path": "/user",

"type": 0,

"parentId": "348193374957735936",

"parent": null,

"sons": null

}, {

"id": "348193868908335105",

"title": "添加用户",

"path": "/user/add",

"type": 0,

"parentId": "348193687223668737",

"parent": null,

"sons": null

}, {

"id": "348193927590842369",

"title": "用户列表",

"path": "/user/list",

"type": 0,

"parentId": "348193687223668737",

"parent": null,

"sons": null

}, {

"id": "348194428344602626",

"title": "权限管理",

"path": "/permission/**",

"type": 0,

"parentId": "348193374957735936",

"parent": null,

"sons": null

}, {

"id": "348194428344602627",

"title": "权限添加",

"path": "/permission/add*",

"type": 0,

"parentId": "348194428344602626",

"parent": null,

"sons": null

}, {

"id": "348194428344602628",

"title": "角色管理",

"path": "/role/list",

"type": 0,

"parentId": "348193374957735936",

"parent": null,

"sons": null

}, {

"id": "348194428344602629",

"title": "demo",

"path": "/demo",

"type": 0,

"parentId": "348193374957735936",

"parent": null,

"sons": null

}],

"resourceRoles": null,

"enabled": true,

"authorities": [{

"authority": "用户管理"

}, {

"authority": "添加用户"

}, {

"authority": "用户列表"

}, {

"authority": "权限管理"

}, {

"authority": "权限添加"

}, {

"authority": "角色管理"

}, {

"authority": "demo"

}],

"accountNonLocked": true,

"accountNonExpired": true,

"credentialsNonExpired": true

}

代码

@SneakyThrows

@Test

public void stringJackson() {

DefaultResourceUser user = fromJson("jack.json", DefaultResourceUser.class);

log.info("user:{}", user.getUsername());

for (GrantedAuthority grantedAuthority : user.getAuthorities()) {

log.info("auth:{}", grantedAuthority.getAuthority());

}

}

结果

[1](https://img2020.cnblogs.com/blog/118538/202012/118538-20201209203450087-419672723.png)