【发布时间】：2019-02-08 17:17:23
【问题描述】：
我正在尝试将 YAML 文件加载到 Map 的实例中。有没有办法在不定义自定义反序列化器的情况下加载它（例如使用注释？）？
这是我的 YAML 文件的示例：
- site: First Site
url: some_url
username: some_name
password: some_password
- site: Second Site
url: its_url
username: its_name
password: its_password
这是将一个“站点配置”反序列化为（由http://www.jsonschema2pojo.org/ 生成）的 java bean 类：
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
import org.apache.commons.lang3.builder.ToStringBuilder;
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
"site",
"url",
"username",
"password"
})
public class SiteConfiguration {
@JsonProperty("site")
private String site;
@JsonProperty("url")
private String url;
@JsonProperty("username")
private String username;
@JsonProperty("password")
private String password;
/**
* No args constructor for use in serialization
*
*/
public SiteConfiguration() {
}
/**
*
* @param site
* @param username
* @param password
* @param url
*/
public SiteConfiguration(String site, String url, String username, String password) {
super();
this.site = site;
this.url = url;
this.username = username;
this.password = password;
}
@JsonProperty("site")
public String getSite() {
return site;
}
@JsonProperty("site")
public void setSite(String site) {
this.site = site;
}
@JsonProperty("url")
public String getUrl() {
return url;
}
@JsonProperty("url")
public void setUrl(String url) {
this.url = url;
}
@JsonProperty("username")
public String getUsername() {
return username;
}
@JsonProperty("username")
public void setUsername(String username) {
this.username = username;
}
@JsonProperty("password")
public String getPassword() {
return password;
}
@JsonProperty("password")
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return new ToStringBuilder(this).append("site", site).append("url", url).append("username", username).append("password", password).toString();
}
}
最后，这是将上面的 YAML 反序列化为 Map 的代码。
private static Map<String,SiteConfiguration> sites;
public static SiteConfiguration getSiteConfiguration(String key) {
if (sites == null) {
ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
try {
// todo this finishes on: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.util.LinkedHashMap` out of START_ARRAY token
// sites = mapper.readValue(YamlReader.class.getClass().getResource("/site-configuration.yaml"), new TypeReference<Map<String,SiteConfiguration>>() {});
SiteConfiguration[] sitesArray = mapper.readValue(YamlReader.class.getClass().getResource("/site-configuration.yaml"), SiteConfiguration[].class);
sites = new HashMap<>();
for (SiteConfiguration site : sitesArray) { //todo is there Jackson built-in deserialization?
sites.put(site.getSite(), site);
}
} catch (Exception e) {
throw new RuntimeException(e);
}
}
return sites.get(key);
}
如您所见，我分两步完成。首先我将文件反序列化为SiteConfiguration 实例的数组，然后将它们放入Map 其中site 字段代表映射键。
有没有办法在省略SiteConfiguration 实例的数组时做同样的事情？是使用自定义反序列化器的唯一方法吗？
【问题讨论】：
标签： java json hashmap jackson yaml