将数据转成JSON

前言

前面我们在使用Strus2的时候，Struts2自带了组件能够让JavaBean对象、集合转成是JSON，不用我们自己拼接…这是非常方便的。但是，我们不一定使用Struts2框架来做开发呀。因此，我们还得学习使用第三方库来将JavaBean对象、集合转成JSON

导入开发包

• commons-io-2.0.1.jar
• commons-lang-2.5.jar
• commons-collections-3.1.jar
• commons-beanutils-1.7.0.jar
• ezmorph-1.0.3.jar
• json-lib-2.1-jdk15.jar

事例代码

package cn.itcast.javaee.js.bean2json;

import net.sf.json.JSONArray;

import java.util.*;

/**
 * 使用第三方工具，将JavaBean对象/List或Set或Map对象转成JSON 
 * @author AdminTC
 */
public class TestBean2Json {
    private static void javabean2json() {
        City city = new City(1,"广州");
        JSONArray jSONArray = JSONArray.fromObject(city);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        //[{"id":1,"name":"广州"}]
    }
    private static void list2json() {
        List<City> cityList = new ArrayList<City>();
        cityList.add(new City(1,"广州"));
        cityList.add(new City(2,"珠海"));
        JSONArray jSONArray = JSONArray.fromObject(cityList);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        //[{"id":1,"name":"广州"},{"id":2,"name":"珠海"}]
    }
    private static void set2json() {
        Set<City> citySet = new LinkedHashSet<City>();
        citySet.add(new City(1,"广州"));
        citySet.add(new City(2,"珠海"));
        JSONArray jSONArray = JSONArray.fromObject(citySet);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        //[{"id":1,"name":"广州"},{"id":2,"name":"珠海"}]
    }
    private static void javabeanlist2json() {
        List<City> cityList = new ArrayList<City>();
        cityList.add(new City(1,"中山"));
        cityList.add(new City(2,"佛山"));
        Province province = new Province(1,"广东",cityList);

        JSONArray jSONArray = JSONArray.fromObject(province);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        /*
          [
             {
              "id":1,
              "name":"广东"
              "cityList":[{"id":1,"name":"中山"},{"id":2,"name":"佛山"}],
             }
          ]
          */
    }
    private static void map2json() {

        List<City> cityList = new ArrayList<City>();
        cityList.add(new City(1,"中山"));
        cityList.add(new City(2,"佛山"));

        Map<String,Object> map = new LinkedHashMap<String,Object>();
        map.put("total",cityList.size());//表示集合的长度
        map.put("rows",cityList);//rows表示集合

        JSONArray jSONArray = JSONArray.fromObject(map);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        //[{"total":2,"rows":[{"id":1,"name":"中山"},{"id":2,"name":"佛山"}]}]

        jsonJAVA = jsonJAVA.substring(1,jsonJAVA.length()-1);
        System.out.println(jsonJAVA);
    }

}

---

总结

把要解析成JSON 的javaBena对象、集合放进下面这段代码即可！

        JSONArray jSONArray = JSONArray.fromObject(map);

无论放进去什么，返回的都是数组