FastjsonTest.java

package demo;

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

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;
import com.alibaba.fastjson.serializer.SerializerFeature;

public class FastjsonTest {
    public static void main(String[] args) {
        User user = new User(1, "张三", new Date());
        test1(user);
        test2(user);
        test3(user);
        test4(user);
        test5(user);
        test6(user);
        test7(user);
        test8();
    }
    // 对象转成JSON字符串
    private static void test1(User user) {
        String s = JSON.toJSONString(user);
        print(1,s);
    }

    // 对象转成JSON字符串，格式化日期
    private static void test2(User user) {
        String s = JSON.toJSONString(user, SerializerFeature.WriteDateUseDateFormat);
        print(2,s);
    }

    // 对象转成JSON字符串，指定日期格式化
    private static void test3(User user) {
        String s = JSON.toJSONStringWithDateFormat(user, "yyyy-MM-dd HH:mm:ss.SSS");
        print(3,s);
    }

    // 对象转成JSON字符串，美化JSON格式
    private static void test4(User user) {
        String s = JSON.toJSONStringWithDateFormat(user, "yyyy-MM-dd", SerializerFeature.PrettyFormat);
        print(4,s);
    }

    // 对象转成JSON字符串，默认字段值为NULL不获取，可以加上SerializerFeature.WriteMapNullValue获取
    private static void test5(User user) {
        String s = JSON.toJSONStringWithDateFormat(user, "yyyy-MM-dd", SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue);
        print(5,s);
    }

    // JSON字符串转化成对象
    private static void test6(User user) {
        String s = JSON.toJSONString(user);
        print(6,s);
        User user2 = JSON.parseObject(s, User.class);
        print(6,user2.toString());
    }
    
    //JSON转成Map<String, Object>
    private static void test7(User user){        
        String json = JSON.toJSONStringWithDateFormat(user, "yyyy-MM-dd");
        Map<String, Object> map1 = JSON.parseObject(json, new TypeReference<Map<String, Object>>(){});        
        print(7, map1.toString());
    }
    
    //JSON转成List<Map>
    private static void test8()    {
        User user1 = new User(1, "张三", new Date());
        User user2 = new User(2, "李四", new Date());
        List<User> list1 = new ArrayList<User>();
        list1.add(user1);
        list1.add(user2);        
        String json = JSON.toJSONString(list1);
        List<Map> maplist = JSON.parseArray(json, Map.class);        
        print(8, maplist.toString());
    }

    private static void print(int method, String info) {
        System.out.print("test" + method + "输出：\r\n" + info + "\r\n");
    }
}

User.java

package demo;

import java.util.Date;
import java.util.List;

public class User {
    private Integer id;
    private String name;
    private Date createDate;    
    private String password;
    
    public User(){        
    }
    
    public User(int id, String name, Date createDate) {
        this.id = id;
        this.name = name;
        this.createDate = createDate;
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }    
    
    public Date getCreateDate() {
        return createDate;
    }

    public void setCreateDate(Date createDate) {
        this.createDate = createDate;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
    
    @Override
    public String toString() {
        return "user [id="+id+",name="+name+",createDate="+createDate+",password="+password+"]";
    }

}

运行结果：

test1输出：
{"createDate":1564739625396,"id":1,"name":"张三"}
test2输出：
{"createDate":"2019-08-02 17:53:45","id":1,"name":"张三"}
test3输出：
{"createDate":"2019-08-02 17:53:45.396","id":1,"name":"张三"}
test4输出：
{
	"createDate":"2019-08-02",
	"id":1,
	"name":"张三"
}
test5输出：
{
	"createDate":"2019-08-02",
	"id":1,
	"name":"张三",
	"password":null
}
test6输出：
{"createDate":1564739625396,"id":1,"name":"张三"}
test6输出：
user [id=1,name=张三,createDate=Fri Aug 02 17:53:45 CST 2019,password=null]
test7输出：
{id=1, name=张三, createDate=2019-08-02}
test8输出：
[{id=1, name=张三, createDate=1564739625490}, {id=2, name=李四, createDate=1564739625490}]