FastJSON解析-----@JSONField注解详解

作者: 周蛋蛋 | 来源:发表于2019-08-20 14:53 被阅读0次

为什么今天要提到FastJson注解的这个属性，我说一下一个场合大家就明白了，你将一个功能开发完毕以后，数据适配完毕，但是后台人员忽然告诉你，后台的返回报文字段名字要做修改，你如果没有遇到这个属性之前，心中千万句草拟马略过，因为要重新去屑bean对象，重新系列，重新获取；但是遇到这个以后，心中不愿意，但是微微一下，点点头告诉他；可以

序列化和反序列化

众所周知，类的对象会随着程序的终止而被垃圾收集器销毁。如果要在不重新创建对象的情况下调用该类，该怎么做？这就可以通过序列化将数据转换为字节流。

序列化
对象序列化的最主要的用处就是在传递和保存对象的时候，保证对象的完整性和可传递性。序列化是把对象转换成有序字节流，以便在网络上传输或者保存在本地文件中。序列化后的字节流保存了Java对象的状态以及相关的描述信息。序列化机制的核心作用就是对象状态的保存与重建。
反序列化
客户端从文件中或网络上获得序列化后的对象字节流后，根据字节流中所保存的对象状态及描述信息，通过反序列化重建对象。
本质上讲，序列化就是把实体对象状态按照一定的格式写入到有序字节流，反序列化就是从有序字节流重建对象，恢复对象状态。

package com.java;

import java.io.Serializable;

import java.util.ArrayList;

import java.util.List;

/**
 * 序列化对象
 * @author -zhengzx-
 *
 */
public class Player implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = -5248069984631225347L;
    public Player(long playerId,  int age, String name) {

        this.playerId = playerId;

        this.age = age;

        this.name = name;

    }

    private long playerId;
    private int age;

    private String name;
    private List<Integer> skills = new ArrayList<>();
    public long getPlayerId() {
        return playerId;
    }
    public void setPlayerId(long playerId) {
        this.playerId = playerId;
    }
    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 List<Integer> getSkills() {
        return skills;
    }

    public void setSkills(List<Integer> skills) {

        this.skills = skills;
    }

}

【1】：对象序列化代码如下，具体细节注释说明：Java中通过对象流 ObjectOutputStream 进行序列化。
【2】：反序列化为对象，具体细节注释说明：Java中通过对象流 ObjectInputStream 进行序列化。


package com.java;

 

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.util.Arrays;

 

/**

 * Description:序列化与反序列化

 * @author zhengzx

 */

public class JavaSerialize {

    public static void main(String[] args) throws Exception {

        Player player = new Player(10001, 21, "teacher");

        player.getSkills().add(10001);

        //序列化

        byte[] bytes = toBytes(player);

        //反序列化

        toPlay(bytes);

    }

    /**  

     * Title: toBytes  

     * Description:序列化对象  

     * @author zhengzx  

     * @throws Exception 

     */  

    public static byte[] toBytes(Object out) throws Exception {

        //用于序列化后存储对象

        ByteArrayOutputStream byteArrayOutputStream = null;

        //java序列化API

        ObjectOutputStream objectOutputStream = null;

        try {

            byteArrayOutputStream = new ByteArrayOutputStream();

            objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);

            //将out对象进行序列化

            objectOutputStream.writeObject(out);

            //测试验证输入（获取字节数组）

            byte[] bs = byteArrayOutputStream.toByteArray();

            //将数组转化为字符串输入

            System.out.println(Arrays.toString(bs));

            return bs;

            

        } catch (IOException e) {

            e.printStackTrace();

        }finally {

            //关闭最外层的流（内部流会自动关闭）

            objectOutputStream.close();

        }

        return null;

    }

    

    /*

     * Title: toPlay  

     * Description:反序列化对象  

     * @author zhengzx  

     * @throws Exception 

     */

    public static void toPlay(byte[] bs) throws Exception {

        //创建存放二进制数据的API

        ByteArrayInputStream byteArrayInputStream = null;

        //创建反序列化对象

        ObjectInputStream objectInputStream = null;

        try {

            byteArrayInputStream = new ByteArrayInputStream(bs);

            objectInputStream = new ObjectInputStream(byteArrayInputStream);

            //校验测试

            Player player = (Player) objectInputStream.readObject();

            System.out.println(player.toString());

        } catch (IOException e) {

            e.printStackTrace();

        }finally {

            objectInputStream.close();

        }

    }

}

输出结果

image.png

fastjson编程式如何使用以及痛点

一般最常见的是这两个方法:
JSON.toJSONString(object):序列化对象,生产字符串
JSON.parse(text):反序列化对象,字符串转json

几个属性

name
format,
serialize
deserialize
serializeUsing,
deserializeUsing

public class TestBean  {

    /**
     * result : 000000
     * message : 请求成功!
     * data : [{"id_number":"61042319","if_select":"0","names":"王引"},{"id_number":"1307309337","if_select":"0","names":"张灵狐"},{"id_number":"610404201109216027","if_select":"0","names":"华怡涵"},{"id_number":"370213194506033833","if_select":"0","names":"哈士奇"},{"id_number":"610404201504165039","if_select":"0","names":"杜锦尚"},{"id_number":"610121197005181908","if_select":"0","names":"齐军平"},{"id_number":"610402198511287002","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"赵纳"},{"id_number":"610404197010155544","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"姚爱玲"},{"id_number":"61040419941123551X","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"郭路裕"},{"id_number":"61040419490705551X","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"王建业"},{"id_number":"610402197504306100","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"曹锋利"},{"id_number":"610404195506205526","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"边淑会"},{"id_number":"610404200402015019","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"杜尚"},{"id_number":"610121194201041570","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"曹志政"},{"id_number":"610404200710135522","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"郭栩彤"},{"id_number":"61040419720408553X","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"郭群利"},{"id_number":"610404194611085525","if_select":"户籍地址不在服务包发布范围,不能进行签约！","names":"司淑云"},{"id_number":"610404197604195017","if_select":"已加入购物车，不能重复操作！","names":"杜龙"}]
     */

    private String result;
    private String message;
    private List<DataBean> data;

    public String getResult() {
        return result;
    }

    public void setResult(String result) {
        this.result = result;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public List<DataBean> getData() {
        return data;
    }

    public void setData(List<DataBean> data) {
        this.data = data;
    }

    public static class DataBean {
        /**
         * id_number : 61042319871110302X
         * if_select : 0
         * names : 王引
         */

        private String id_number;
        private String if_select;
        private String names;

        public String getId_number() {
            return id_number;
        }

        public void setId_number(String id_number) {
            this.id_number = id_number;
        }

        public String getIf_select() {
            return if_select;
        }

        public void setIf_select(String if_select) {
            this.if_select = if_select;
        }

        public String getNames() {
            return names;
        }

        public void setNames(String names) {
            this.names = names;
        }
    }
}}

测试：

这样去写只是证明了序列化成功了：

public class Main2Activity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        String json = "{\n" +
                "    \"data\": [\n" +
                "        {\n" +
                "            \"id_number\": \"61042319\",\n" +
                "            \"if_select\": \"0\",\n" +
                "            \"names\": \"王引\"\n" +
                "        },\n" +
                "        {\n" +
                "            \"id_number\": \"1307309337\",\n" +
                "            \"if_select\": \"0\",\n" +
                "            \"names\": \"张灵狐\"\n" +
                "        }\n" +
                "    ],\n" +
                "    \"message\": \"请求成功!\",\n" +
                "    \"result\": \"000000\"\n" +
                "}";
        TestBean testBean = JSON.parseObject(json, TestBean.class);
        Log.e("string",JSON.toJSONString(testBean));


    }
}

输出，证明了我们序列化成功了