maven中央仓库: http://central.maven.org/maven2/com/alibaba/fastjson/
Sourceforge.net : https://sourceforge.net/projects/fastjson/files/
在maven中如何配置fastjson依赖 fastjson最新版本都会发布到maven中央仓库，你可以直接依赖。

<dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>fastjson</artifactId>
     <version>1.2.21</version>
</dependency>

<dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>fastjson</artifactId>
     <version>1.1.55.android</version>
</dependency>

常用接口

package com.alibaba.fastjson;
public abstract class JSON {
      public static final String toJSONString(Object object);
      public static final <T> T parseObject(String text, Class<T> clazz, Feature... features);
}

序列化：

String jsonString = JSON.toJSONString(obj);

反序列化：

VO vo = JSON.parseObject("...", VO.class);

范型序列化：

import com.alibaba.fastjson.TypeReference;

List<VO> list = JSON.parseObject("...", new TypeReference<List<VO>>() {});

Demo

序列化：

import com.alibaba.fastjson.JSON;

Group group = new Group();
group.setId(0L);
group.setName("admin");

User guestUser = new User();
guestUser.setId(2L);
guestUser.setName("guest");

User rootUser = new User();
rootUser.setId(3L);
rootUser.setName("root");

group.addUser(guestUser);
group.addUser(rootUser);

String jsonString = JSON.toJSONString(group);

System.out.println(jsonString);

反序列化：

String jsonString = ...;
Group group = JSON.parseObject(jsonString, Group.class);

Group.java

public class Group {

    private Long       id;
    private String     name;
    private List<User> users = new ArrayList<User>();

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public List<User> getUsers() {
        return users;
    }

    public void setUsers(List<User> users) {
        this.users = users;
    }

        public void addUser(User user) {
            users.add(user);
        }
}

User.java

public class User {

    private Long   id;
    private String name;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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