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);
    }
}