主题：一个json-lib.jar转换复杂对象的问题?
相关的bean如下
TVO.java代码如下
Java代码
- package demo;
- import java.util.*;
- import com.easylotto.lottobar.bean.BaseEntity;
- import com.easylotto.lottobar.bean.ReqCommandVO;
- public class TVO extends BaseEntity{
- private String tname;
- private List<Person> rcvoList;
- private Map map;
- public List<Person> getRcvoList() {
- return rcvoList;
- }
- public void setRcvoList(List<Person> rcvoList) {
- this.rcvoList = rcvoList;
- }
- public String getTname() {
- return tname;
- }
- public void setTname(String tname) {
- this.tname = tname;
- }
- public Map getMap() {
- return map;
- }
- public void setMap(Map map) {
- this.map = map;
- }
- /**
- * @param args
- */
- public static void main(String[] args) {
- // TODO Auto-generated method stub
- }
- }
package demo;
import java.util.*;
import com.easylotto.lottobar.bean.BaseEntity;
import com.easylotto.lottobar.bean.ReqCommandVO;
public class TVO extends BaseEntity{
private String tname;
private List<Person> rcvoList;
private Map map;
public List<Person> getRcvoList() {
return rcvoList;
}
public void setRcvoList(List<Person> rcvoList) {
this.rcvoList = rcvoList;
}
public String getTname() {
return tname;
}
public void setTname(String tname) {
this.tname = tname;
}
public Map getMap() {
return map;
}
public void setMap(Map map) {
this.map = map;
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
}
}
Person.java如下
Java代码
- package demo;
- public class Person {
- private String name;
- private String age;
- public Person(String name,String age){
- this.name=name;
- this.age=age;
- }
- public String getAge() {
- return age;
- }
- public void setAge(String age) {
- this.age = age;
- }
- public String getName() {
- return name;
- }
- public void setName(String name) {
- this.name = name;
- }
- }
package demo;
public class Person {
private String name;
private String age;
public Person(String name,String age){
this.name=name;
this.age=age;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
测试类如下:
Java代码
- package demo;
- import net.sf.json.*;
- import java.util.*;
- import com.easylotto.lottobar.bean.ReqCommandVO;
- import com.easylotto.lottobar.bean.SocketCommandEntity;
- /**
- * Json使用测试类
- * @author peidw
- *
- */
- public class JsonDemo {
- public String JsonStr2Object(){
- String str="{'map':{'a2':'A2','a1':'A1'},'rcvoList':[{'age':'20','name':'小裴'},{'age':'58','name':'小庞'}],'tname':'xxname'}";
- JSONObject jo=JSONObject.fromObject(str);
- TVO sce=null;
- if(jo!=null){
- sce=(TVO)jo.toBean(jo, TVO.class);
- List alist=sce.getRcvoList();
- System.out.println(alist.size());
- Person rcvo=null;
- for(int i=0;i<alist.size();i++){
- rcvo=(Person)alist.get(i);
- System.out.print(rcvo.getName()+"-"+rcvo.getAge());
- }
- }
- return "测试";
- }
- public void Object2JsonStr(){
- TVO tvo=new TVO();
- tvo.setTname("xxname");
- List <Person>a=new ArrayList();
- a.add(new Person("小裴","20"));
- a.add(new Person("小庞","58"));
- tvo.setRcvoList(a);
- Map map=new HashMap();
- map.put("a1", "A1");
- map.put("a2", "A2");
- tvo.setMap(map);
- JSONObject jo=JSONObject.fromObject(tvo);
- System.out.println(jo);
- }
- public static void main(String[] args){
- JsonDemo jd=new JsonDemo();
- jd.JsonStr2Object();
- //jd.Object2JsonStr();
- }
- }
package demo;
import net.sf.json.*;
import java.util.*;
import com.easylotto.lottobar.bean.ReqCommandVO;
import com.easylotto.lottobar.bean.SocketCommandEntity;
/**
* Json使用测试类
* @author peidw
*
*/
public class JsonDemo {
public String JsonStr2Object(){
String str="{'map':{'a2':'A2','a1':'A1'},'rcvoList':[{'age':'20','name':'小裴'},{'age':'58','name':'小庞'}],'tname':'xxname'}";
JSONObject jo=JSONObject.fromObject(str);
TVO sce=null;
if(jo!=null){
sce=(TVO)jo.toBean(jo, TVO.class);
List alist=sce.getRcvoList();
System.out.println(alist.size());
Person rcvo=null;
for(int i=0;i<alist.size();i++){
rcvo=(Person)alist.get(i);
System.out.print(rcvo.getName()+"-"+rcvo.getAge());
}
}
return "测试";
}
public void Object2JsonStr(){
TVO tvo=new TVO();
tvo.setTname("xxname");
List <Person>a=new ArrayList();
a.add(new Person("小裴","20"));
a.add(new Person("小庞","58"));
tvo.setRcvoList(a);
Map map=new HashMap();
map.put("a1", "A1");
map.put("a2", "A2");
tvo.setMap(map);
JSONObject jo=JSONObject.fromObject(tvo);
System.out.println(jo);
}
public static void main(String[] args){
JsonDemo jd=new JsonDemo();
jd.JsonStr2Object();
//jd.Object2JsonStr();
}
}
出现的异常如下
2
Exception in thread "main" java.lang.ClassCastException: net.sf.ezmorph.bean.MorphDynaBean
at demo.JsonDemo.JsonStr2Object(JsonDemo.java:26)
at demo.JsonDemo.main(JsonDemo.java:53)
使用的是json-lib-2.2.1-jdk15.jar包,请问这是怎么回事,怎么解决?
这个问题有两个地方值得考虑:
1、一个就是json-lib好像是使用反射实现的,那你的Person类如果没有无参数的构造方法的话，很危险;
2、在你的转化的代码上并没有告诉程序把rcvoList里的数据为何种类型
为此正确的做法是，为Person添加无参数的构造方法，同时修改代码为:
if(jo!=null){
Map<String, Class> m = new HashMap<String, Class>();
m.put("rcvoList", Person.class);
sce=(TVO)JSONObject.toBean(jo, TVO.class, m);
这样应该就OK了…………