java转JSON串的几种方式

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<Card> cardList=new ArrayList<Card>();
	
	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<Card> getCardList() {
		return cardList;
	}
	public void setCardList(List<Card> 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<Card> cards=new ArrayList<Card>();
    	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

 	<dependency>
		<groupId>com.alibaba</groupId>
		<artifactId>fastjson</artifactId>
		<version>1.2.15</version>
	</dependency>

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"}

代码示例 点击打开链接