Java轉JSON串的幾種方式

更新時間：2018年05月16日 15:26:17 投稿：mrr

本文給大家總結一下java轉json串的幾種方式，每種方式通過實例代碼給大家介紹的非常詳細，感興趣的朋友跟隨腳本之家小編一起學習吧

昨天在與對端系統調接口的時候，對端系統對我們傳過去的json串老是處理不了，后來查原因是應為我們傳過去的json串里有json對象數組，因為我們的json串存在表里的，取出來是作為json字符串放到json數組里的，所以帶了雙引號，對端認為是字符串，不是json對象所以處理不了。

[{"cardName":"bankCard1","cardCode":"888888888","cardValue":99999999},{"cardName":"bankCard2","cardCode":"999999999","cardValue":222222222}] 這種是正確的json對象數組，["{"cardName":"bankCard1","cardCode":"888888888","cardValue":99999999}","{"cardName":"bankCard2","cardCode":"999999999","cardValue":222222222}"]，這種是json字符串數組。

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<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<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

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