Java-＞ fastjson的使用实例

秒速五厘米 2023-10-18 18:08 90阅读 0赞

fastjson 是实体对象转Json的格式的工具jar，是一个java语言编写的高性能且功能完善的JSON库，它采用一种“假定有序快速匹配”的算法，把`JSON Parse` 的性能提升到了极致。它的接口简单易用，已经被广泛使用在缓存序列化，协议交互，Web输出等各种应用场景中

<dependency>  
                <groupId>com.alibaba</groupId>  
                <artifactId>fastjson</artifactId>  
                <version>1.2.30</version>  
    </dependency>

实例1：

import java.util.ArrayList;
    import java.util.List;
    import com.alibaba.fastjson.JSON;
    import com.alibaba.fastjson.JSONObject;
    public class Fastjson {
    	public static void main(String[] args) {
    		People people=new People();
    		people.setAge(120);
    		people.setName("xixixi");
    		List<People> list=new ArrayList<People>();
    		list.add(people);
    		list.add(people);
    		System.out.println(JSON.toJSON(people));
    		System.out.println(JSONObject.toJSON(people));
    		System.out.println(JSON.toJSON(list));
    		String peoplejson="{'name':'hheheheh','age':13}";
    		People p=JSONObject.parseObject(peoplejson, People.class);
    		System.out.println(p.getAge());
    		//String listjson="[{'name':'heheh','age':22}]";*/
    	}
    }
    
    
    
    
    public class People {
    	private String name;
    	private int age;
    	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;
    	}
    
    
    }

输出：
    {"name":"xixixi","age":120}
    {"name":"xixixi","age":120}
    [{"name":"xixixi","age":120},{"name":"xixixi","age":120}]
    13

实例2

public static void main(String[] args) throws Throwable
    	{
    		List<Picture> lits = new ArrayList<>();
    		Picture p1 = new Picture("xiaoming", null, DateUtil.toDate("2019-05-13", "yyyy-MM-dd"), 1);
    		Picture p2 = new Picture("xiaohong", null, DateUtil.toDate("2019-05-13", "yyyy-MM-dd"), 1);
    		lits.add(p1);
    		lits.add(p2);
    		System.out.println( DateUtil.toString(new Date(), "yyyy-MM-dd"));
    		//为null 的不会输出
    		String jsonString =JSON.toJSONString(lits);
    		System.out.println(jsonString);
    		//为null 的也会输出
    		String jsonString1=JSON.toJSONString(lits,SerializerFeature.WriteMapNullValue,SerializerFeature.WriteNullListAsEmpty,SerializerFeature.WriteNullStringAsEmpty,SerializerFeature.WriteNullNumberAsZero);
    		System.out.println(jsonString1);
    	}
    
    //----------------------------------------------
    
    class Picture {
    	private Integer pic_id;
    	private String pic_name;
    	private String pic_url;
    	private String pic_type;
    	private Date pic_ctime;
    	private Date pic_ltime;
    	private String pic_intro;
    	private Integer state;
    	
    	public Picture(){}
    	
    	public Picture(String pic_name, String pic_url,Date pic_ltime,Integer state) {
    		this.pic_name = pic_name;
    		this.pic_url = pic_url;
    		this.pic_ltime = pic_ltime;
    		this.state = state;
    	}
        ...................................
    }

输出：

2019-05-13
    [{"pic_ltime":1557676800000,"pic_name":"xiaoming","state":1},{"pic_ltime":1557676800000,"pic_name":"xiaohong","state":1}]
    [{"id":0,"pic_ctime":null,"pic_intro":"","pic_ltime":1557676800000,"pic_name":"xiaoming","pic_type":"","pic_url":"","state":1},{"id":0,"pic_ctime":null,"pic_intro":"","pic_ltime":1557676800000,"pic_name":"xiaohong","pic_type":"","pic_url":"","state":1}]

如果不使用创建实体如下：

JSONObject object =JSON.parseObject("JSon格式字符串");

实例3：获取json 字符串中某个值：

String jsonStr="{'code':100,'data':{'name':'小明','age':16}}";
    
    //先把String对象转换成json对象
    JSONObject object= JSONObject.parseObject(jsonStr);
    
    System.out.println(object.get("code").toString()));
    System.out.println(object.getJSONObject("data").get("name"));

更多可参考：[java中string与json互相转化\_jsonstring是什么\_a55650892的博客-CSDN博客][java_string_json_jsonstring_a55650892_-CSDN]

[java_string_json_jsonstring_a55650892_-CSDN]: https://blog.csdn.net/a5650892/article/details/78764410