以下總結一下java轉JSON串的幾種方式：

1、將java對象轉成json串

2、通過JSONObject生成json串

3、通過json字符串生成json串

代碼通過阿里的fastjson包實現。

代碼如下：

1、Person類，包含Crad的List

package?com.doit8.test.jsontest.pojo;

import?java.util.ArrayList;

import?java.util.List;

public?class?Person?{

private?String username;

private?String email;

private?String sex;

private?int?age;

private?List?cardList=new?ArrayList();

public?String?getUsername()?{

return?username;

}

public?void?setUsername(String username)?{

this.username = username;

}

public?String?getEmail()?{

return?email;

}

public?void?setEmail(String email)?{

this.email = email;

}

public?String?getSex()?{

return?sex;

}

public?void?setSex(String sex)?{

this.sex = sex;

}

public?int?getAge()?{

return?age;

}

public?void?setAge(int?age)?{

this.age = age;

}

public?List?getCardList()?{

return?cardList;

}

public?void?setCardList(List?cardList)?{

this.cardList = cardList;

}

}

2、Card類

package?com.doit8.test.jsontest.pojo;

public?class?Card?{

private?String cardName;

private?String cardCode;

private?Integer cardValue;

public?String?getCardName()?{

return?cardName;

}

public?void?setCardName(String cardName)?{

this.cardName = cardName;

}

public?String?getCardCode()?{

return?cardCode;

}

public?void?setCardCode(String cardCode)?{

this.cardCode = cardCode;

}

public?Integer?getCardValue()?{

return?cardValue;

}

public?void?setCardValue(Integer cardValue)?{

this.cardValue = cardValue;

}

}

3、JSON處理測試類

package com.doit8.test.jsontest;

import?java.util.ArrayList;

import?java.util.List;

import?com.alibaba.fastjson.JSON;

import?com.alibaba.fastjson.JSONArray;

import?com.alibaba.fastjson.JSONObject;

import?com.doit8.test.jsontest.pojo.Card;

import?com.doit8.test.jsontest.pojo.Person;

/**?

* JSON轉換?

*?

*/

?

public?class?App?

{

public?static?void?main(?String[] args )

{

//1。通過對象生成JSON串，對象里包含對象數組轉成JSON串。 ?

Person person=new?Person();

person.setUsername("xiejava");

person.setSex("man");

person.setAge(38);

person.setEmail("xiejava@ishareread.com");

Card card1=new?Card();

card1.setCardName("bankCard1");

card1.setCardCode("888888888");

card1.setCardValue(99999999);

Card card2=new?Card();

card2.setCardName("bankCard1");

card2.setCardCode("999999999");

card2.setCardValue(222222222);

//對象數組 ?

List?cards=new?ArrayList();

cards.add(card1);

cards.add(card2);

person.setCardList(cards);

String?json =?JSON.toJSON(person).toString();

System.out.println(json);

//2.通過JSON對象生成JSON串 ?

JSONObject jObject=new?JSONObject();

jObject.put("username",?"xiejava");

jObject.put("sex",?"man");

jObject.put("age",?38);

jObject.put("email",?"xiejava@ishareread.com");

//通過JSONArray包裝對象數組 ?

JSONArray jArray=new?JSONArray();

jArray.addAll(cards);

jObject.put("cardList", jArray);

String?json2=jObject.toJSONString();

System.out.println(json2);

//3.通過JSON對象生成JSON串 ?

JSONObject jObject2=new?JSONObject();

jObject2.put("username",?"xiejava");

jObject2.put("sex",?"man");

jObject2.put("age",?38);

jObject2.put("email",?"xiejava@ishareread.com");

//構造JSON字符串 ?

String?cardjsonStr1="{\"cardName\":\"bankCard1\",\"cardCode\":\"888888888\",\"cardValue\":99999999}";

String?cardjsonStr2="{\"cardName\":\"bankCard2\",\"cardCode\":\"999999999\",\"cardValue\":222222222}";

JSON.parseObject(cardjsonStr1);

JSONArray jArray2=new?JSONArray();

//將JSON字符串轉成JSON對象，加入到JSONArray，[注意一定要用JSON.parseObject()方法轉換成JSON對象，否則還是字符串，轉成JSON串的時候會帶雙引號。] ?

jArray2.add(JSON.parseObject(cardjsonStr1));

jArray2.add(JSON.parseObject(cardjsonStr2));

jObject2.put("cardList", jArray2);

String?json3=jObject2.toJSONString();

System.out.println(json3);

}

}

pom.xml中引入fastjson包

?

com.alibabagroupId>

fastjsonartifactId>

1.2.15version>

dependency>

運行結果

{"cardList":[{"cardName":"bankCard1","cardCode":"888888888","cardValue":99999999},{"cardName":"bankCard1","cardCode":"999999999","cardValue":222222222}],"sex":"man","age":38,"email":"xiejava@ishareread.com","username":"xiejava"} ?

{"cardList":[{"cardCode":"888888888","cardName":"bankCard1","cardValue":99999999},{"cardCode":"999999999","cardName":"bankCard1","cardValue":222222222}],"sex":"man","age":38,"email":"xiejava@ishareread.com","username":"xiejava"} ?

{"cardList":[{"cardName":"bankCard1","cardCode":"888888888","cardValue":99999999},{"cardName":"bankCard2","cardCode":"999999999","cardValue":222222222}],"sex":"man","age":38,"email":"xiejava@ishareread.com","username":"xiejava"}

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