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<DefaultResourceUser> {

        @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<GrantedAuthority> simpleGrantedAuthorities = new ArrayList<>();
                    Iterator<JsonNode> 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)

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java~jackson实现接口的反序列化

现实

几个序列化方式