JSON解析实践,使用了工具库Json-lib,解决了添加Jar包后出现的Exception in thread "main" java.lang.NoClassDefFoundError错误,并且附上实例代码,主要是利用库生成JSON字符串。另附上相关资源的下载链接。
JSON解析实例——使用Json-lib
Json-lib下载及使用
本文介绍用一个类库进行JSON解析。
工具下载地址:http://sourceforge.net/projects/json-lib/?source=directory
下载后,有这么三个东东:
将第一个Jar包导入项目即可用其中的API。
(具体方法:在项目中建立libs文件夹,将第一个包复制进去,然后在Java Build Path里面Add External JARs…)
第二个包是文档,直接右键解压缩之后就会得到html文档,入口是index.html,当然也可以利用工具(jd2chm.exe)将其转换为chm格式这样查看更方便。
第三个包是源码,感兴趣或者以后碰到问题了可以看看。
附加包:解决 Exception in thread "main" java.lang.NoClassDefFoundError
导入了上面的包之后,运行程序会抛出运行时异常:Exception in thread "main" java.lang.NoClassDefFoundError。
搜索之后,才知道还要添加另外的包,我是从这里下载的:
http://download.csdn.net/download/guoyongxue/4423006
如果没有积分,也可以去我的网盘下载:
http://pan.baidu.com/share/link?shareid=1066468750&uk=2701745266
也就是说,一共需要这么多包:
需要把它们全部加入libs文件夹,并且把它们添加进Build Path中。
程序实例:利用Json-lib生成JSON字符串
时间关系,代码不再过多解释,项目结构如图:
其中的类:
package com.shengqishiwind.domain;
public class Person
{
private int id;
private String name;
private String address;
public Person()
{
}
public Person(int id, String name, String address)
{
super();
this.id = id;
this.name = name;
this.address = address;
}
public int getId()
{
return id;
}
public void setId(int id)
{
this.id = id;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public String getAddress()
{
return address;
}
public void setAddress(String address)
{
this.address = address;
}
@Override
public String toString()
{
return "Person [id=" + id + ", name=" + name + ", address=" + address
+ "]";
}
}
Person.java
package com.shengqishiwind.tools;
import net.sf.json.JSONObject;
public class JsonTools
{
public JsonTools()
{
}
public static String createJsonString(String key, Object value)
{
String jsonString = null;
JSONObject jsonObject = new JSONObject();
jsonObject.put(key, value);
jsonString = jsonObject.toString();
return jsonString;
}
}
package com.shengqishiwind.service;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.shengqishiwind.domain.Person;
public class JsonService
{
public JsonService()
{
}
public Person getPerson()
{
Person person = new Person(001, "ZhangSan", "Beijing");
return person;
}
public List<Person> getPersonsList()
{
List<Person> personsList = new ArrayList<Person>();
Person person1 = new Person(001, "ZhangSan", "Beijing");
Person person2 = new Person(002, "LiSi", "Tianjin");
Person person3 = new Person(003, "WangWu", "Shanghai");
personsList.add(person1);
personsList.add(person2);
personsList.add(person3);
return personsList;
}
public List<String> getStringsList()
{
List<String> stringsList = new ArrayList<String>();
stringsList.add("南京");
stringsList.add("杭州");
stringsList.add("承德");
stringsList.add("哈尔滨");
stringsList.add("重庆");
return stringsList;
}
public List<Map<String, Object>> getMapsList()
{
List<Map<String, Object>> mapsList = new ArrayList<Map<String, Object>>();
for (int i = 0; i < 3; ++i)
{
Map<String, Object> map = new HashMap<String, Object>();
map.put("id", i);
map.put("name", "Name_" + i);
map.put("address", "Address_" + i);
mapsList.add(map);
}
return mapsList;
}
}
最后测试的主程序:
package com.shengqishiwind.jsontest;
import com.shengqishiwind.domain.Person;
import com.shengqishiwind.service.JsonService;
import com.shengqishiwind.tools.JsonTools;
public class Test1
{
public static void main(String[] args)
{
String msg = "";
JsonService service = new JsonService();
Person person = service.getPerson();
// 一个Person对象
msg = JsonTools.createJsonString("aPerson", person);
System.out.println(msg);
// 一个List,里面有若干Person对象
msg = JsonTools.createJsonString("Persons", service.getPersonsList());
System.out.println(msg);
// 一个List,里面有若干String对象
msg = JsonTools.createJsonString("StringsList",
service.getStringsList());
System.out.println(msg);
// 一个List,里面有若干Map对象,每个Map对象中存储了若干个键值对
msg = JsonTools.createJsonString("MapsList", service.getMapsList());
System.out.println(msg);
}
}
程序在控制台输出如下:
{"aPerson":{"address":"Beijing","id":1,"name":"ZhangSan"}}
{"Persons":[{"address":"Beijing","id":1,"name":"ZhangSan"},{"address":"Tianjin","id":2,"name":"LiSi"},{"address":"Shanghai","id":3,"name":"WangWu"}]}
{"StringsList":["南京","杭州","承德","哈尔滨","重庆"]}
{"MapsList":[{"id":0,"address":"Address_0","name":"Name_0"},{"id":1,"address":"Address_1","name":"Name_1"},{"id":2,"address":"Address_2","name":"Name_2"}]}
参考资料
老罗Android开发视频教程。
本博客上一篇博文:JSON数据解析 基础知识及链接收集
Json-lib工具类库下载地址:
http://sourceforge.net/projects/json-lib/?source=directory
http://sourceforge.net/projects/json-lib/files/json-lib/json-lib-2.4/
附加包下载地址:
http://download.csdn.net/download/guoyongxue/4423006
我的百度网盘中全部Json-lib资源下载:
http://pan.baidu.com/share/link?shareid=1066468750&uk=2701745266
如果觉得有帮助,就点个推荐吧~~~
作者: 圣骑士Wind
出处: 博客园: 圣骑士Wind
Github: https://github.com/mengdd
微信公众号: 圣骑士Wind