学步园

 关于json是什么，在这里就不做介绍，相信看这篇文章的同学都知道。

Gson--是一款Google公司的用来解析json数据格式的库

Fastjson--是一款阿里巴巴的用来解析json数据格式的库，据说目前最快。

首先介绍Gson的使用（下载前需要去下载,www.json.org都有链接，自己去找）

1、将一个JavaBen转换为json字符串

方便起见，把所有的类写在同一个文件里面

public class Main 
{
	public static void main(String[] args) 
	{
		Person p=new Person(23,"gavin");
		SchoolInfo school=new SchoolInfo("good","sh");
		p.setInfo(school);
		
		
		List<Friend> friends=new ArrayList();
		Friend f1=new Friend("aviva1");
		Friend f2=new Friend("aviva2");
		Friend f3=new Friend("aviva3");
		Friend f4=new Friend("aviva4");
		
		friends.add(f1);
		friends.add(f2);
		friends.add(f3);
		friends.add(f4);
		
		p.setFriends(friends);
		
		
		
		Gson gson=new Gson();
		System.out.println(gson.toJson(p));
		
		
	}
}

class Person
{
	int age;
	String name;
	SchoolInfo info;
	List<Friend> friends;
	public Person(int age,String name)
	{
		this.age=age;
		this.name=name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public SchoolInfo getInfo() {
		return info;
	}
	public void setInfo(SchoolInfo info) {
		this.info = info;
	}
	public List<Friend> getFriends() {
		return friends;
	}
	public void setFriends(List<Friend> friends) {
		this.friends = friends;
	}

}

class SchoolInfo
{
	String name;
	String addr;
	
	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAddr() {
		return addr;
	}

	public void setAddr(String addr) {
		this.addr = addr;
	}

	public SchoolInfo(String name,String addr)
	{
		this.name=name;
		this.addr=addr;
	}
}

class Friend
{
	String name;
	
	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Friend(String name)
	{
		this.name=name;
	}
}

运行结果：

{"age":23,"name":"gavin","info":{"name":"good","addr":"sh"},"friends":[{"name":"aviva1"},{"name":"aviva2"},{"name":"aviva3"},{"name":"aviva4"}]}

2、将上面得到的字符串转换成一个Persn

String txt=gson.toJson(p);
		
		Person person=gson.fromJson(txt, Person.class);
		System.out.println(person);
		

3、json字符串和List之间转换

编写一个Student 类

class Student 
 {
	  int age;
	  String name;
	  
	  public Student(int age,String name)
	  {
		  this.age=age;
		  this.name=name;
	  }
	  
 }

Main方法

Student s1=new Student(1,"gavin");
		Student s2=new Student(2,"aviva");
		
		List<Student> stus=new ArrayList();
		stus.add(s1);
		stus.add(s2);
		
		Gson gson=new Gson();
		
		System.out.println(gson.toJson(stus));

结果

[{"age":1,"name":"gavin"},{"age":2,"name":"aviva"}]

将上述字符串转换为List

String t=gson.toJson(stus);
		List<Student> list=gson.fromJson(t, new TypeToken<List<Student>>(){}.getType());
		System.out.println(list);

3、实现Map和json字符串转换

	HashMap<String ,String> map=new HashMap();
		map.put("1", "gavin");
		map.put("2", "aviva");
		Gson gson=new Gson();
		
		System.out.println(gson.toJson(map));
		
		
		String t=gson.toJson(map);
		
		HashMap<String,String> m=gson.fromJson(t, new TypeToken<HashMap<String,String>>(){}.getType());

由于时间有限，在此fastjsaon就不在做介绍，其用法和Gson基本相同..............