java如何使用反射从POJO获取属性名和值?
所以我在写一个“POJO到JSON”的转换器。我希望能够传入List<T>
对象并转换为JSON
希望这会有意义
/**
*
* NOT COMPLETE!!! OBVIOUSLY!!!
*/
public abstract class Jsonator<T> implements Serializable {
private Class<T> entityClass;
private JSONObject json;
private JSONArray jsonArray;
public Jsonator(Class<T> entityClass) {
this.entityClass = entityClass;
}
public void convert(List<T> paObjectList) throws IllegalArgumentException, IllegalAccessException {
json = new JSONObject();
jsonArray = new JSONArray();
try {
for (Object obj : paObjectList) {
JSONObject objJson = new JSONObject();
Class<?> kls = obj.getClass();
Field[] fields = kls.getFields();
for (Field field : fields) {
objJson.put(field.getName(), (T) field.get(obj));
}
jsonArray.add(objJson);
}
json.put("results", jsonArray);
}
catch (Exception ex) {
}
}
public String error() {
return "ERROR";
}
public String results() {
if (json != null) {
return json.toJSONString();
}
return "[]";
}
}
当我到达Object obj
部分时,我的obj
是正确的。我可以调试它并查看类的名称和值
让我们假设课堂是这样的:
public class User {
private firstName;
private lastName;
... getters....setters....etc...
}
所以现在,obj
是一个网站。
好的,然后我尝试获取字段名(firstName,lastName),但是fields对象是空的
我做错了什么
谢谢
编辑
我成功了!这是尚未完成的代码,但它正在做我现在想要的事情。 我听说谷歌和杰克逊也会这么做。如果有人能提供一个关于如何有选择地从POJO中挑选房产的好链接,那么我洗耳恭听
或者更好的是,我想知道为什么我不应该这样做
谢谢
Jsonator(未完成)
import java.io.Serializable;
import java.lang.reflect.Field;
import java.util.List;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
/**
*
* @author Cecil.Meeks
*/
public abstract class Jsonator<T> implements Serializable {
private Class<T> entityClass;
private JSONObject json;
private JSONArray jsonArray;
public Jsonator(Class<T> entityClass) {
this.entityClass = entityClass;
}
public void convert(List<T> paObjectList) throws IllegalArgumentException, IllegalAccessException {
json = new JSONObject();
jsonArray = new JSONArray();
try {
for (Object obj : paObjectList) {
JSONObject objJson = new JSONObject();
Class<?> kls = obj.getClass();
Field[] fields = kls.getDeclaredFields();
for (Field field : fields) {
field.setAccessible(true);
objJson.put(field.getName(), field.get(obj));
}
jsonArray.add(objJson);
}
json.put("results", jsonArray);
}
catch (SecurityException ex) {
ex.printStackTrace();
}
catch (Exception ex) {
ex.printStackTrace();
}
}
public String error() {
return "ERROR";
}
public String results() {
if (json != null) {
return json.toJSONString();
}
return "[]";
}
}
站点类
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
@Entity
@Table(name = "Sites")
public class Site implements Serializable {
private String siteKey;
private String site;
private String siteType;
private String address1;
private String address2;
private String city;
private String zipCode;
private String createdBy;
private String glCode;
public Site() {
}
@Id
@GenericGenerator(name = "generator", strategy = "guid", parameters = {})
@GeneratedValue(generator = "generator")
public String getSiteKey() {
return siteKey;
}
public void setSiteKey(String siteKey) {
this.siteKey = siteKey;
}
@Column(name = "Site", unique = true, length = 125, nullable = false)
public String getSite() {
return site;
}
public void setSite(String site) {
this.site = site;
}
@Column(name = "SiteType", unique = false, length = 8, nullable = true)
public String getSiteType() {
return siteType;
}
public void setSiteType(String siteType) {
this.siteType = siteType;
}
@Column(name = "Address1", unique = false, length = 125, nullable = true)
public String getAddress1() {
return address1;
}
public void setAddress1(String address1) {
this.address1 = address1;
}
@Column(name = "Address2", unique = false, length = 125, nullable = true)
public String getAddress2() {
return address2;
}
public void setAddress2(String address2) {
this.address2 = address2;
}
@Column(name = "City", unique = false, length = 125, nullable = true)
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
@Column(name = "ZipCode", unique = false, length = 50, nullable = true)
public String getZipCode() {
return zipCode;
}
public void setZipCode(String zipCode) {
this.zipCode = zipCode;
}
@Column(name = "CreatedBy", unique = false, length = 125, nullable = true)
public String getCreatedBy() {
return createdBy;
}
public void setCreatedBy(String createdBy) {
this.createdBy = createdBy;
}
@Column(name = "GLCode", unique = false, length = 11, nullable = true)
public String getGlCode() {
return glCode;
}
public void setGlCode(String glCode) {
this.glCode = glCode;
}
}
示例
public class SiteJsonator extends Jsonator<Site> {
public SiteJsonator() {
super(Site.class);
}
}
@Controller
@RequestMapping(value = "/sites")
public class SitesController {
@Autowired
private SiteService siteService;
@RequestMapping(value = "/", method = RequestMethod.GET, headers = "Accept=application/json")
@ResponseBody
public String index(ModelMap map) {
SiteJsonator list = new SiteJsonator();;
try {
list.convert(siteService.getAll());
return list.results();
}
catch (Exception ex) {
return list.error();
}
}
}
更新2
对于那些感兴趣的人来说,以下是更好的Jsonator
:
https://gist.github.com/3893242
您可以传入一个“exclude”字符串[],但它不会包含这些字符串。此外,它还有一个标准的“结果、消息等”,我们喜欢在AJAX请求中传回它。对ExtJS很好
# 1 楼答案
而不是kls。获取可能需要使用kls的字段。getDeclaredFields()。如果Jason object是你关心的问题,我向你推荐一个Jackson Codhaus图书馆。在其中,您可以从POJO获取或设置JsonString。。。嗯
# 2 楼答案
需要使用^{} 来包含私有字段,^{} 只列出公共字段
使用} 方法
private
字段时,您也会遇到访问限制问题,因此您可能也想研究一下^{