使用FastJson对JSON字符串、JSON对象及JavaBean之间的相互转换

maven依赖包：

1 <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
2 <dependency>
3     <groupId>com.alibaba</groupId>
4     <artifactId>fastjson</artifactId>
5     <version>1.2.47</version>
6 </dependency>

一、FastJson是用于java后台处理json格式数据的一个工具包，包括“序列化”和“反序列化”两部分，它具备如下特征：

（1）速度最快，测试表明，fastjson具有极快的性能，超越任其他的java json parser。
（2）功能强大，完全支持java bean、集合、Map、日期、Enum，支持范型，支持自省。
（3）无依赖，能够直接运行在Java SE 5.0以上版本

二、FastJson对于json格式字符串的解析主要用到了一下三个类：

（1）JSON：fastJson的解析器，用于JSON格式字符串与JSON对象及javaBean之间的转换。
（2）JSONObject：fastJson提供的json对象。
（3）JSONArray：fastJson提供json数组对象。

三、测试所需的实体类

 1 package com.xxx.controller;
 2  
 3 import java.io.Serializable;
 4 public class Data implements Serializable {
 5     private static final long serialVersionUID = -6957361951748382519L;
 6     private String id;
 7     private String suborderNo;
 8     private String organUnitType;
 9     private String action;
10     private String parent;
11     private String organUnitFullName;
12     private Long ordinal;
13     get、set方法省略。。。
14 }

 1 package com.xxx.controller;
 2 
 3 import java.io.Serializable;
 4 import java.util.ArrayList;
 5 import java.util.List;
 6 
 7 public class Error implements Serializable {
 8 
 9 private static final long serialVersionUID = -432908543160176349L;
10 
11 private String code;
12 private String message;
13 private String success;
14 private List<Data> data = new ArrayList<>();
15 get、set方法省略。。。
16 }

四、JSON格式字符串、JSON对象及JavaBean之间的相互转换

4.1) JAVA对象转JSON字符串

 1 //java对象转json字符串
 2 public static void beanTojson() {
 3 Data data = new Data();
 4 data.setAction("add");
 5 data.setId("1");
 6 data.setOrdinal(8L);
 7 data.setOrganUnitFullName("testJSON");
 8 data.setParent("0");
 9 data.setSuborderNo("58961");
10 
11 String s = JSON.toJSONString(data);
12 System.out.println("toJsonString()方法：s=" + s);
13 //输出结果{"action":"add","id":"1","ordinal":8,"organUnitFullName":"testJSON","parent":"0","suborderNo":"58961"}
14 }

4.2) A. JSON字符串转JSON对象

 1 //json字符串转json对象
 2 public static void jsonToJsonBean() {
 3 String s ="{"action":"add","id":"1","ordinal":8,"organUnitFullName":"testJSON","parent":"0","suborderNo":"58961"}";
 4 
 5 JSONObject jsonObject = JSON.parseObject(s);
 6 String action = jsonObject.getString("action");
 7 String id = jsonObject.getString("id");
 8 System.out.println("action ="+action);//add
 9 System.out.println("id ="+id);//1
10 System.out.println("jsonObject ="+jsonObject);
11 //action =add
12 //id =1
13 //jsonObject ={"parent":"0","organUnitFullName":"testJSON","action":"add","id":"1","suborderNo":"58961","ordinal":8}
14 }

B. 复杂JSON格式字符串与JSONObject之间的转换

 1 public static void jsonToBean() {
 2 String str ="{"meta":{"code":"0","message":"同步成功!"},"data":{"orderno":"U_2018062790915774","suborderno":"SUB_2018062797348039","type":"organunit","result":{"organunit":{"totalCount":2,"successCount":0,"failCount":2,"errors":[{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"254","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false},{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"255","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false}]},"role":{"totalCount":0,"successCount":0,"failCount":0,"errors":[]},"user":{"totalCount":0,"successCount":0,"failCount":0,"errors":[]}}}}";
 3 JSONObject jsonObject = JSON.parseObject(str);
 4 JSONObject data = jsonObject.getJSONObject("data");
 5 JSONObject result = data.getJSONObject("result");
 6 
 7 String organunit1 = result.getString("organunit");
 8 System.out.println(organunit1);
 9 JSONObject organunit = result.getJSONObject("organunit");
10 
11 JSONArray errors2 = organunit.getJSONArray("errors");
12 
13 List<Error> error = JSON.parseObject(errors2.toJSONString(), new TypeReference<List<Error>>() {
14 });
15 }

4.3) A. JSON字符串转JAVA简单对象

 1 //json字符串转java简单对象
 2 public static void jsonStrToJavaBean() {
 3 String s ="{"action":"add","id":"1","ordinal":8,"organUnitFullName":"testJSON","parent":"0","suborderNo":"58961"}";
 4 Data data = JSON.parseObject(s, Data.class);
 5 System.out.println("data对象"+data.toString());
 6 System.out.println("action="+data.getAction()+"---id="+data.getId());
 7 //data对象Data{id='1', suborderNo='58961', organUnitType='null', action='add', parent='0', organUnitFullName='testJSON', ordinal=8}
 8 //action=add---id=1
 9 
10 /**
11 * 另一种方式转对象
12 */
13 Data dd = JSON.parseObject(s, new TypeReference<Data>() {});
14 System.out.println("另一种方式获取data对象"+dd.toString());
15 System.out.println("另一种方式获取="+dd.getAction()+"---id="+dd.getId());
16 //另一种方式获取data对象Data{id='1', suborderNo='58961', organUnitType='null', action='add', parent='0', organUnitFullName='testJSON', ordinal=8}
17 //另一种方式获取=add---id=1
18 }

B. JSON字符串数组类型与JAVA对象的转换

测试json字符串

1 {"errors":[{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"254","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false},{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"255","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false}]}

 1 //json字符串--数组型与JSONArray对象之间的转换
 2 public static void jsonStrToJSONArray() {
 3 String str = "{"errors":[{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"254","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false},{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"255","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false}]}";
 4 JSONObject jsonObject = JSON.parseObject(str);
 5 JSONArray error = jsonObject.getJSONArray("errors");
 6 List<Error> errors = JSON.parseObject(error.toJSONString(), new TypeReference<List<Error>>() {
 7 });
 8 for (Error e: errors) {
 9 //Error的属性
10 System.out.println("Error属性="+e.getSuccess());
11 System.out.println("Error属性="+e.getCode());
12 System.out.println("Error属性="+e.getMessage());
13 //Error集合属性
14 List<Data> datas = e.getData();
15 for (Data d: datas) {
16 System.out.println("data对象属性="+d.getId());
17 System.out.println("data对象属性="+d.getAction());
18 System.out.println("data对象属性="+d.getSuborderNo());
19 }
20 }
21 //Error属性=false
22 //Error属性=UUM70004
23 //Error属性=组织单元名称不能为空
24 //data对象属性=254
25 //data对象属性=add
26 //data对象属性=SUB_2018062797348039
27 
28 //Error属性=false
29 //Error属性=UUM70004
30 //Error属性=组织单元名称不能为空
31 //data对象属性=255
32 //data对象属性=add
33 //data对象属性=SUB_2018062797348039
34 }

C. JSON字符串第二种方法-->数组类型与JAVA对象的转换

 1 //第二种方法：json字符串--数组型与JSONArray对象之间的转换
 2 @Test
 3 public void jsonStrToJSONArray2() {
 4 String str = "{"errors":[{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"254","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false},{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"255","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false}]}";
 5 //获取jsonobject对象
 6 JSONObject jsonObject = JSON.parseObject(str);
 7 //把对象转换成jsonArray数组
 8 JSONArray error = jsonObject.getJSONArray("errors");
 9 //error==>[{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"254","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false},{"code":"UUM70004","message":"组织单元名称不能为空","data":{"id":"255","suborderNo":"SUB_2018062797348039","organUnitType":"部门","action":"add","parent":"10000","ordinal":0,"organUnitFullName":"组织单元全称"},"success":false}]
10 //将数组转换成字符串
11 String jsonString = JSONObject.toJSONString(error);//将array数组转换成字符串
12 //将字符串转成list集合
13 List<Error> errors = JSONObject.parseArray(jsonString, Error.class);//把字符串转换成集合
14 for (Error e: errors) {
15 //Error的属性
16 System.out.println("另一种数组转换Error属性="+e.getSuccess());
17 System.out.println("另一种数组转换Error属性="+e.getCode());
18 System.out.println("另一种数组转换Error属性="+e.getMessage());
19 //Error集合属性
20 List<Data> datas = e.getData();
21 for (Data d: datas) {
22 System.out.println("另一种数组转换data对象属性="+d.getId());
23 System.out.println("另一种数组转换data对象属性="+d.getAction());
24 System.out.println("另一种数组转换data对象属性="+d.getSuborderNo());
25 }
26 }
27 //另一种数组转换Error属性=false
28 //另一种数组转换Error属性=UUM70004
29 //另一种数组转换Error属性=组织单元名称不能为空
30 //另一种数组转换data对象属性=254
31 //另一种数组转换data对象属性=add
32 //另一种数组转换data对象属性=SUB_2018062797348039
33 
34 //另一种数组转换Error属性=false
35 //另一种数组转换Error属性=UUM70004
36 //另一种数组转换Error属性=组织单元名称不能为空
37 //另一种数组转换data对象属性=255
38 //另一种数组转换data对象属性=add
39 //另一种数组转换data对象属性=SUB_2018062797348039
40 }

4.4) JAVA对象转JSON对象

 1 //javabean转json对象
 2 public static void jsonBenToJsonObject() {
 3 Data data = new Data();
 4 data.setAction("add");
 5 data.setId("1");
 6 data.setOrdinal(8L);
 7 data.setOrganUnitFullName("testJSON");
 8 data.setParent("0");
 9 data.setSuborderNo("58961");
10 JSONObject jsonObj = (JSONObject) JSON.toJSON(data);
11 JSON json = (JSON) JSON.toJSON(data);
12 System.out.println("jsonObj"+jsonObj);
13 System.out.println("json对象"+json);
14 //jsonObj{"parent":"0","organUnitFullName":"testJSON","action":"add","id":"1","suborderNo":"58961","ordinal":8}
15 //json对象{"parent":"0","organUnitFullName":"testJSON","action":"add","id":"1","suborderNo":"58961","ordinal":8}
16 }

五、后记

（1）对于JSON对象与JSON格式字符串的转换可以直接用 toJSONString()这个方法。
（2）javaBean与JSON格式字符串之间的转换要用到：JSON.toJSONString(obj);
（3）javaBean与json对象间的转换使用：JSON.toJSON(obj)，然后使用强制类型转换，JSONObject或者JSONArray。

参考例文 --------------- >https://blog.csdn.net/xuforeverlove/article/details/80842148