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("[email protected]"); 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", "[email protected]"); //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", "[email protected]"); //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":"[email protected]","username":"xiejava"}
{"cardList":[{"cardCode":"888888888","cardName":"bankCard1","cardValue":99999999},{"cardCode":"999999999","cardName":"bankCard1","cardValue":222222222}],"sex":"man","age":38,"email":"[email protected]","username":"xiejava"}
{"cardList":[{"cardName":"bankCard1","cardCode":"888888888","cardValue":99999999},{"cardName":"bankCard2","cardCode":"999999999","cardValue":222222222}],"sex":"man","age":38,"email":"[email protected]","username":"xiejava"}