alibaba架包FastJson使用例子

　　alibaba的架包FastJson可以对json字符串进行快捷的类型转换。下面是一些各种类型转换的使用例子。

一、下载FastJson的架包，并导入项目中，如下：

Maven项目pom.xml配置如下：

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.32</version>
</dependency>

二、附上代码例子，如下：

1、创建2个实体类，供后面例子使用，如下：

 public class School {
     private String id;
     private String name;
     List<User> students = new ArrayList<User>();
     public String getId() {
         return id;
     }
     public void setId(String id) {
         this.id = id;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public List<User> getStudents() {
         return students;
     }
     public void setStudents(List<User> students) {
         this.students = students;
     }
 }

 public class User {
     private String id;
     private String name;

     public User(){

     }
     public User(String id, String name){
         this.id = id;
         this.name = name;
     }

     public String getId() {
         return id;
     }
     public void setId(String id) {
         this.id = id;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
 }

2、Json字符串与Map、List、object之间的相互转换例子，如下：

 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 import com.alibaba.fastjson.JSON;
 import com.alibaba.fastjson.JSONArray;
 import com.alibaba.fastjson.JSONObject;

 public class TestFastJson {

     public static void main(String[] args){
         json2JsonObject();//将Json字符串转换为JSONObject对象
         json2JavaBean();//将Json字符串转换为JavaBean对象
         json2JsonArray();//将Json字符串转换为JSONArray对象
         json2JavaBeanList();//将Json字符串转换为JavaBean的集合
         javaBean2Json();//将JavaBean转换为Json格式的数据
         javaBean2JsonObject();//将JavaBean转换为JSONObject对象
         json2ListInMap();//从Json字符串的Map中获取List对象
         list2JsonInMap();//将含list的Map对象转换为Json字符串
     }

     private static void json2JsonObject() {
         String s = "{\"name\":\"peter\"}";
         JSONObject object = JSON.parseObject(s);
         System.out.println(object.get("name"));
     }

     private static void json2JavaBean() {
         String s = "{\"id\":\"17051801\",\"name\":\"lucy\"}";
         User user = JSON.parseObject(s, User.class);
         System.out.println(user.getId());
         System.out.println(user.getName());
     }

     private static void json2JsonArray() {
         String s = "[{\"id\":\"17051801\",\"name\":\"lucy\"},{\"id\":\"17051802\",\"name\":\"peter\"}]";
         JSONArray array = JSON.parseArray(s);
         for (int i = 0; i < array.size(); i++) {
             //JSONArray中的数据转换为String类型需要在外边加"";不然会报出类型强转异常！
             String str = array.get(i)+"";
             JSONObject object = JSON.parseObject(str);
             System.out.println(object.get("name"));
         }
     }

     private static void json2JavaBeanList() {
         String s = "[{\"id\":\"17051801\",\"name\":\"lucy\"},{\"id\":\"17051802\",\"name\":\"peter\"}]";
         List<User> list = JSON.parseArray(s, User.class);
         for (User user : list) {
             System.out.println(user.getName());
         }
     }

     private static void javaBean2Json() {
         User user = new User("17051801", "lucy");
         String string = JSON.toJSONString(user);
         System.out.println(string);
     }

     private static void javaBean2JsonObject() {
         User user = new User("17051801", "lucy");
         JSONObject json = (JSONObject) JSON.toJSON(user);
         System.out.println(json.get("id"));
     }

     private static void json2ListInMap() {
         String s = "{json:[{id:\"17051801\",\"name\":\"lucy\"},{id:\"17051802\",\"name\":\"peter\"},"
                 + "{id:\"17051803\",\"name\":\"tom\"},{id:\"17051804\",\"name\":\"lily\"}]}";
         //将Json字符串转换为JSONObject对象,并取出list对象的值
         JSONObject object = JSON.parseObject(s);
         Object objArray = object.get("json");
         String str = objArray+"";
         //方式1:转换成JSONArray对象形式
         JSONArray array = JSON.parseArray(str);
         for (int i = 0; i < array.size(); i++) {
             JSONObject obj = JSON.parseObject(array.get(i)+"");
             System.out.println(obj.get("name"));
         }
         //方式2:转换成List<JavaBean>形式
         List<User> list = JSON.parseArray(str, User.class);
         for (User user : list) {
             System.out.println(user.getName());
         }
     }

     private static void list2JsonInMap() {
         //方式1:构建一个带有list的JavaBean对象
         School school = new School();
         school.setId("1");
         school.setName("schoolA");

         User user1 = new User();
         user1.setId("17051801");
         user1.setName("lucy");
         User user2 = new User();
         user2.setId("17051802");
         user2.setName("peter");

         school.getStudents().add(user1);
         school.getStudents().add(user2);
         //将JavaBean对象转换成Json字符串
         String string1 = JSON.toJSONString(school);
         System.out.println(string1);

         //方式2:构建一个带有list的Map对象
         Map<String, Object> map1 = new HashMap<String,Object>();
         map1.put("id", "17051801");
         map1.put("name", "lucy");

         Map<String, Object> map2 = new HashMap<String,Object>();
         map2.put("id", "17051802");
         map2.put("name", "peter");

         List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
         list.add(map1);
         list.add(map2);

         Map<String, Object> map = new HashMap<String,Object>();
         map.put("id", "1");
         map.put("name", "schoolA");
         map.put("students", list);
         //将map对象转换成Json字符串
         String string2 = JSON.toJSONString(map);
         System.out.println(string2);
     }
 }