昨天在与对端系统调接口的时候，对端系统对我们传过去的json串老是处理不了，后来查原因是应为我们传过去的json串里有json对象数组，因为我们的json串存在表里的，取出来是作为json字符串放到json数组里的，所以带了双引号，对端认为是字符串，不是json对象所以处理不了。

[{"cardName":"bankCard1","cardCode":"888888888","cardValue":99999999},{"cardName":"bankCard2","cardCode":"999999999","cardValue":222222222}] 这种是正确的json对象数组，["{"cardName":"bankCard1","cardCode":"888888888","cardValue":99999999}","{"cardName":"bankCard2","cardCode":"999999999","cardValue":222222222}"]，这种是json字符串数组。

以下总结一下java转JSON串的几种方式：

1、将java对象转成json串

2、通过JSONObject生成json串

3、通过json字符串生成json串

代码通过阿里的fastjson包实现。

代码如下：

1、Person类，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类

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处理测试类

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转换

*

*/

public class App

{

public static void main( String[] args )

{

//1。通过对象生成JSON串，对象里包含对象数组转成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);

//对象数组

List cards=new ArrayList();

cards.add(card1);

cards.add(card2);

person.setCardList(cards);

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

System.out.println(json);

//2.通过JSON对象生成JSON串

JSONObject jObject=new JSONObject();

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

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

jObject.put("age", 38);

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

//通过JSONArray包装对象数组

JSONArray jArray=new JSONArray();

jArray.addAll(cards);

jObject.put("cardList", jArray);

String json2=jObject.toJSONString();

System.out.println(json2);

//3.通过JSON对象生成JSON串

JSONObject jObject2=new JSONObject();

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

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

jObject2.put("age", 38);

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

//构造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();

//将JSON字符串转成JSON对象，加入到JSONArray，[注意一定要用JSON.parseObject()方法转换成JSON对象，否则还是字符串，转成JSON串的时候会带双引号。]

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.alibaba

fastjson

1.2.15

运行结果

{"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"}