1、jackson 框架：这个框架提供了JsonGenerator   ，ObjectMapper两个类通过这两个类提供的方法可以将java 对象转化为json 对象，json 数组格式，也可以将json对象、数组格式转化为java对象。

2、json-lib框架也可以进行json格式和java 对象之间的相互转化，json-lib提供的类主要有：JSONObject ,JSONArray....

3、展现使用两种框架进行相互转化：

一、json-lib:

package com.inspur.json;  import java.util.ArrayList;  import java.util.List;  import net.sf.json.JSONArray;  import net.sf.json.JSONObject;  public class JSONTest {      public static void main(String[] args) {          User u = new User();          u.setName("name1");          u.setAge(1);          u.setPhone("123");          User u2 = new User();          u2.setName("name2");          u2.setAge(2);          u2.setPhone("321");          List list = new ArrayList();          list.add(u);            list.add(u2);            // 创建JSONObject 对象            JSONObject jobg = new JSONObject();           // 创建JSONObject 对象            JSONArray arr = new JSONArray();           // 将对象转化为json对象的格式            JSONObject str = jobg.fromObject(u);         // 将list集合转化为json数组的格式          JSONArray str1 = arr.fromObject(list);          System.out.print(str);          System.out.print("\n");          System.out.print(str1);        }  }    /*  运行结果  */    {"age":1,"name":"name1","phone":"123"}  [{"age":1,"name":"name1","phone":"123"},{"age":2,"name":"name2","phone":"321"}]

二、jackson框架提供的两个类 JsonGenerator    ObjectMapper

package com.jackson.test;  import java.util.ArrayList;  import java.util.List;  import org.codehaus.jackson.JsonEncoding;  import org.codehaus.jackson.JsonGenerator;  import org.codehaus.jackson.map.ObjectMapper;  public class Test {      public static void main(String[] args) {          User u = new User();          u.setName("name1");          u.setAge(1);          u.setSex("man");          User u2 = new User();          u2.setName("name2");          u2.setAge(2);          u2.setSex("man");          List list = new ArrayList();          list.add(u);          list.add(u2);          ObjectMapper obj = new ObjectMapper();          JsonGenerator jg = null;            try {              jg = obj.getJsonFactory().createJsonGenerator(System.out,                      JsonEncoding.UTF8);              System.out.println("jsonGenerator");              // writeObject可以转换java对象，eg:JavaBean/Map/List/Array等              jg.writeObject(u);              System.out.println();              jg.writeObject(list);              System.out.println();              System.out.println("ObjectMapper");              // writeValue具有和writeObject相同的功能                            obj.writeValue(System.out, list);          } catch (Exception e) {              e.printStackTrace();          }      }  }      /  *   运行结果  */    jsonGenerator  {"name":"name1","age":1,"sex":"man"}   [{"name":"name1","age":1,"sex":"man"},{"name":"name2","age":2,"sex":"man"}]  ObjectMapper  [{"name":"name1","age":1,"sex":"man"},{"name":"name2","age":2,"sex":"man"}]

jackson框架jar包下载：http://download.csdn.net/detail/qh_java/7767473