2. Json-lib 和 Gson的对比
上一篇已经给大家介绍过json的表达方式，这一篇讲开始介绍如何在java中生成json。
1.用json-lib生成json
要用到的jar包：commons-beanutils-1.8.3.jar, commons-collections-3.2.1.jar, commons-lang-2.4.jar, commons-logging-1.1.1.jar, ezmorph-1.0.6.jar, json-lib-2.3-jdk15.jar
//1.对象package com.hx.test;import com.hx.entity.Person;import net.sf.json.JSONObject;public class JsonTest {public static void main(String[] args) {Person person = new Person();person.setName("tom");person.setAddress("UK");person.setAge(14);JSONObject json = JSONObject.fromObject(person);System.out.println(json.toString());}}//输出结果为：//{"address":"UK","age":14,"name":"tom"}//2.数组和集合package com.hx.test;import java.util.ArrayList;import java.util.List;import net.sf.json.JSONArray;public class JsonTest {public static void main(String[] args) {List<String> fruit = new ArrayList<String>();fruit.add("apple");fruit.add("pear");fruit.add("orange");fruit.add("banana");JSONArray fruits = JSONArray.fromObject(fruit);System.out.println(fruits.toString());}}//输出结果：//["apple","pear","orange","banana"]//2）Map集合//Map集合比较特殊，因为 key-value键值对的对应方式，所以咱们应当用JSONObject来生成json。package com.hx.test;import java.util.HashMap;import java.util.Map;import net.sf.json.JSONObject;public class JsonTest {public static void main(String[] args) {Map<String, String> map = new HashMap<String, String>();map.put("001", "apple");map.put("002", "pear");map.put("003", "orange");map.put("004", "banana");JSONObject json = JSONObject.fromObject(map);System.out.println(json.toString());}}//输出结果：//{"004":"banana","001":"apple","002":"pear","003":"orange"}//3) Map集合扩展package com.hx.test;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import net.sf.json.JSONObject;public class JsonTest {public static void main(String[] args) {Map<String, List<String>> map = new HashMap<String, List<String>>();List<String> strList1 = new ArrayList<String>();strList1.add("aa");strList1.add("bb");strList1.add("cc");List<String> strList2 = new ArrayList<String>();strList2.add("dd");strList2.add("ee");strList2.add("ff");List<String> strList3 = new ArrayList<String>();strList3.add("gg");strList3.add("hh");strList3.add("ii");map.put("001", strList1);map.put("002", strList2);map.put("003", strList3);JSONObject json = JSONObject.fromObject(map);System.out.println(json.toString());}}//输出结果：//{"001":["aa","bb","cc"],"002":["dd","ee","ff"],"003":["gg","hh","ii"]}/* 和json-lib相比，Gson操作就相当的更简单了 不管是对象还是数组，还是上面较复杂的map集合， 操作都是一样的，Gson是出自google，应为比较小巧，所以其自己系统android上面用的也 是这个。*///因为操作都一样，所以在这里只给大家演示一种情况。//别忘了导jar包：[i]gson-2.1.jar[/i]package com.hx.test;import com.google.gson.Gson;import com.hx.entity.Person;public class GsonTest {public static void main(String[] args) {Person person = new Person();person.setAddress("UK");person.setAge(14);person.setName("tom");Gson gson = new Gson();System.out.println(gson.toJson(person));}}//输出结果：//{"name":"tom","age":14,"address":"UK"}