主流JSON库的Javabean与JSON的互转，以及String类的JSON串解析为JSON对象

爱被打了一巴掌 2023-08-17 17:10 106阅读 0赞

参考：[https://blog.csdn.net/suyimin2010/article/details/81406813][https_blog.csdn.net_suyimin2010_article_details_81406813]

[https://blog.csdn.net/DevolperFront/article/details/99515755][https_blog.csdn.net_DevolperFront_article_details_99515755]

Maven依赖：

<dependency>
    			<groupId>net.sf.json-lib</groupId>
    			<artifactId>json-lib</artifactId>
    			<version>2.4</version>
    			<classifier>jdk15</classifier>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>com.google.guava</groupId>
    			<artifactId>guava</artifactId>
    			<version>20.0</version>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>com.google.collections</groupId>
    			<artifactId>google-collections</artifactId>
    			<version>1.0</version>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>org.projectlombok</groupId>
    			<artifactId>lombok</artifactId>
    			<version>1.16.22</version>
    			<scope>provided</scope>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>com.google.code.gson</groupId>
    			<artifactId>gson</artifactId>
    			<version>2.8.5</version>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>com.alibaba</groupId>
    			<artifactId>fastjson</artifactId>
    			<version>1.2.50</version>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>net.minidev</groupId>
    			<artifactId>json-smart</artifactId>
    			<version>2.3</version>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>org.json</groupId>
    			<artifactId>json</artifactId>
    			<version>20190722</version>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>com.googlecode.json-simple</groupId>
    			<artifactId>json-simple</artifactId>
    			<version>1.1.1</version>
    		</dependency>
    
    		<dependency>
    			<groupId>com.fasterxml.jackson.core</groupId>
    			<artifactId>jackson-databind</artifactId>
    			<version>2.9.8</version>
    		</dependency>
    		
    		<dependency>
    			<groupId>com.fasterxml.jackson.core</groupId>
    			<artifactId>jackson-annotations</artifactId>
    			<version>2.9.0</version>
    		</dependency>

准备工作：

package cn.cuit.testa0;
    
    
    import lombok.Data;
    
    
    @Data
    public class FullName
    {
        private String firstName;
    
        private String middleName;
    
        private String lastName;
    
        public FullName()
        {}
    
        public FullName(String firstName, String middleName, String lastName)
        {
            this.firstName = firstName;
            this.middleName = middleName;
            this.lastName = lastName;
        }
    
        @Override
        public String toString()
        {
            return "[firstName=" + firstName + ", middleName=" + middleName + ", lastName=" + lastName + "]";
        }
    }

package cn.cuit.testa0;
    
    
    import java.util.Date;
    import java.util.List;
    import java.util.Map;
    
    import lombok.Data;
    
    
    @Data
    public class Person
    {
        private String name;
    
        private FullName fullName;
    
        private int age;
    
        private Date birthday;
    
        private List<String> hobbies;
    
        private Map<String, String> clothes;
    
        private List<Person> friends;
    
        @Override
        public String toString()
        {
            StringBuilder str = new StringBuilder(
                "Person [name=" + name + ", fullName=" + fullName + ", age=" + age + ", birthday=" + birthday + ", hobbies=" + hobbies + ", clothes=" + clothes + "]\n");
            if (friends != null)
            {
                str.append("Friends:\n");
                for (Person f : friends)
                {
                    str.append("\t").append(f);
                }
            }
            return str.toString();
        }
    }

package cn.cuit.testa0;
    
    
    import com.alibaba.fastjson.JSON;
    
    
    public class FastJsonUtil
    {
        public static String bean2Json(Object obj)
        {
            return JSON.toJSONString(obj);
        }
    
        public static <T> T json2Bean(String jsonStr, Class<T> objClass)
        {
            return JSON.parseObject(jsonStr, objClass);
        }
    }

package cn.cuit.testa0;
    
    
    import com.google.gson.Gson;
    import com.google.gson.GsonBuilder;
    import com.google.gson.JsonElement;
    import com.google.gson.JsonParser;
    
    
    public class GsonUtil
    {
        // Gson gson = new Gson(); 两种创建方式
        private static Gson gson = new GsonBuilder().create();
    
        public static String bean2Json(Object obj)
        {
            return gson.toJson(obj);
        }
    
        public static <T> T json2Bean(String jsonStr, Class<T> objClass)
        {
            return gson.fromJson(jsonStr, objClass);
        }
    
        public static String jsonFormatter(String uglyJsonStr)
        {
            Gson gson = new GsonBuilder().setPrettyPrinting().create();
            JsonParser jp = new JsonParser();
            JsonElement je = jp.parse(uglyJsonStr);
            return gson.toJson(je);
        }
    }

package cn.cuit.testa0;
    
    
    import java.io.IOException;
    
    import com.fasterxml.jackson.core.JsonProcessingException;
    import com.fasterxml.jackson.databind.ObjectMapper;
    
    
    public class JacksonUtil
    {
        private static ObjectMapper mapper = new ObjectMapper();
    
        public static String bean2Json(Object obj)
        {
            try
            {
                return mapper.writeValueAsString(obj);
            }
            catch (JsonProcessingException e)
            {
                e.printStackTrace();
                return null;
            }
        }
    
        public static <T> T json2Bean(String jsonStr, Class<T> objClass)
        {
            try
            {
                return mapper.readValue(jsonStr, objClass);
            }
            catch (IOException e)
            {
                e.printStackTrace();
                return null;
            }
        }
    }

package cn.cuit.testa0;
    
    
    import net.sf.json.JSONObject;
    
    
    public class JsonLibUtil
    {
    
        public static String bean2Json(Object obj)
        {
            JSONObject jsonObject = JSONObject.fromObject(obj);
            return jsonObject.toString();
        }
    
        @SuppressWarnings("unchecked")
        public static <T> T json2Bean(String jsonStr, Class<T> objClass)
        {
            return (T)JSONObject.toBean(JSONObject.fromObject(jsonStr), objClass);
        }
    }

package cn.cuit.testa0;
    
    
    import net.minidev.json.JSONValue;
    
    
    public class JsonSmartUtil
    {
        public static String bean2Json(Object obj)
        {
            return JSONValue.toJSONString(obj);
        }
    
        public static <T> T json2Bean(String jsonStr, Class<T> objClass)
        {
            return JSONValue.parse(jsonStr, objClass);
        }
    }

测试代码：

package cn.cuit.testa0;
    
    
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    import org.json.simple.parser.JSONParser;
    import org.json.simple.parser.ParseException;
    import org.junit.Before;
    import org.junit.Test;
    
    import com.alibaba.fastjson.JSON;
    import com.fasterxml.jackson.databind.JsonNode;
    import com.fasterxml.jackson.databind.ObjectMapper;
    import com.google.common.collect.Maps;
    import com.google.gson.JsonArray;
    import com.google.gson.JsonObject;
    import com.google.gson.JsonParser;
    
    import net.minidev.json.JSONValue;
    import net.sf.json.JSONArray;
    import net.sf.json.JSONObject;
    
    
    /**
      * @ClassName: TestJson
      * @Description: 所有主流JSON库的对象转JSON和JSON转对象，以及String类的JSON串解析为JSON对象
      * @lib: 
      *     json-lib-2.4-jdk15【性能较差，用法还可以】
      *     fastjson
      *     json-smart
      *     org.json【对JavaBean与JSON之前的互转支持差】
      *     json-simple【不太好用,与其他库用法有所差异，主要用于Map的支持，对JavaBean几乎不支持】
      *     Gson
      *     Jackson
      * @author CUITLLB
      * @date Sep 24, 2019 12:06:39 PM
      * @Copyright: Copyright (c) 2018 
      * @Company:IBM
      * 
      * @JSON 库性能参考：https://blog.csdn.net/DevolperFront/article/details/99515755
      */
    
    public class TestJson
    {
        
        // 用的时候注意判断获取到的是否为null，否则易产生空指针异常，这里没有做校验
        
        // 需要解析的字符串
        String jsonString = "{\n" + 
            "    \"status\": 0,\n" + 
            "    \"message\": \"Everything is ok.\",\n" + 
            "    \"result\": {\n" + 
            "        \"total_count\": 1,\n" + 
            "        \"users\": [\n" + 
            "            {\n" + 
            "                \"user_id\": \"a017c149c08e35acd968598944\",\n" + 
            "                \"domain_id\": \"hcxm\",\n" + 
            "                \"status\": \"ACTIVATED\",\n" + 
            "                \"state\": \"NORMAL\",\n" + 
            "                \"username\": \"uf085268\",\n" + 
            "                \"name\": \"Li Linbo, BBF-421(IBM Simba)\",\n" + 
            "                \"pinyin\": \"Li Linbo, BBF-421(IBM Simba)\",\n" + 
            "                \"initial\": \"Li Linbo, BBF-421(IBM Simba)\",\n" + 
            "                \"nickname\": \"Li Linbo, BBF-421(IBM Simba)\",\n" + 
            "                \"phone\": \"\",\n" + 
            "                \"email\": \"\",\n" + 
            "                \"gender\": \"UNKNOWN\",\n" + 
            "                \"disabled\": false,\n" + 
            "                \"initial_password\": true,\n" + 
            "                \"agreement_confirmed\": false,\n" + 
            "                \"biological_auth_enabled\": false,\n" + 
            "                \"source_type\": \"LDAP\"\n" + 
            "            }\n" + 
            "        ]\n" + 
            "    }\n" + 
            "}";
        
        private Person person;
        
        @Before
        public void prepare() {
            List<Person> friends = new ArrayList<Person>();
            friends.add(this.createAPerson("Judiy", null));
            friends.add(this.createAPerson("Tony", null));
            friends.add(this.createAPerson("Mark", null));
            person = createAPerson("Li Linbo", friends);
        }
        
        private Person createAPerson(String name, List<Person> friends) {
            Person newPerson=new Person();
            newPerson.setName(name);
            newPerson.setFullName(new FullName("Li_first", "Lin_middle", "bo_last"));
            newPerson.setAge(24);
            List<String> hobbies=new ArrayList<String>();
            hobbies.add("music");
            hobbies.add("swing");
            hobbies.add("coding");
            newPerson.setHobbies(hobbies);
            Map<String,String> clothes=new HashMap<String, String>();
            clothes.put("coat", "Nike");
            clothes.put("trousers", "Onitsuka Tiger");
            clothes.put("shoes", "AJ");
            newPerson.setClothes(clothes);
            newPerson.setFriends(friends);
            return newPerson;
        }
        
        public static void main(String[] args)
        {
        }
        
        // Json-lib 4 String
        @Test
        public void testJsonLib4String() {
            JSONObject fromObject = JSONObject.fromObject(jsonString);
            System.out.println(fromObject);
    
            JSONObject object = (JSONObject)fromObject.get("result");
            System.out.println(object);
    
            JSONArray jsonArray = object.getJSONArray("users");
            System.out.println(jsonArray);
    
            object = (JSONObject)jsonArray.get(0);
            System.out.println(object);
            
            System.out.println(object.get("username"));
        }
        
        // Json-lib 4 Object
        @Test
        public void testJsonLib4Object() {
            // Object -> String
            String bean2Json = JsonLibUtil.bean2Json(person);
            System.out.println(bean2Json);
            
            // String -> Object
            Person json2Bean = JsonLibUtil.json2Bean(bean2Json, Person.class);
            // 直接输出对象会报异常, 解析出来后，里面的friends属性是一个MorphDynaBean包装Bean，
            // Person中直接遍历的时候直接转为Person就报类型转换异常，参考：https://www.cnblogs.com/longshiyVip/p/4608098.html
            System.out.println(json2Bean.getFriends().get(0));
            //System.out.println(json2Bean.getFriends().get(0).getAge()); // 报错
            System.out.println(json2Bean.getAge());
            
            // 上述问题的解决方法
            Map<String, Class<?>> classMap = Maps.newHashMap();
            classMap.put("friends", Person.class);
            // 需要注意的一点是，这里第一个参数不是String而是一个JsonObject
            Person bean = (Person)JSONObject.toBean(JSONObject.fromObject(bean2Json), Person.class, classMap);
            System.out.println(bean);
            System.out.println(bean.getFriends().get(0).getAge());
        }
        
        // fastjson 4 String
        @Test
        public void testFastJson4String() {
            com.alibaba.fastjson.JSONObject parseObject = JSON.parseObject(jsonString);
            System.out.println(parseObject);
            
            com.alibaba.fastjson.JSONObject jsonObject = parseObject.getJSONObject("result");
            System.out.println(jsonObject);
            
            com.alibaba.fastjson.JSONArray jsonArray = jsonObject.getJSONArray("users");
            com.alibaba.fastjson.JSONObject object = (com.alibaba.fastjson.JSONObject)jsonArray.get(0);
            System.out.println(object);
            
            System.out.println(object.get("username"));
        }
        
        // fastjson 4 Object
        @Test
        public void testFastJson4Object() {
            // Object -> String
            String bean2Json = FastJsonUtil.bean2Json(person);
            System.out.println(bean2Json);
            
            // String -> Object
            Person json2Bean = FastJsonUtil.json2Bean(bean2Json, Person.class);
            System.out.println(json2Bean);
        }
        
        // json-smart 4 String
        @Test
        public void testJsonSmart4String() {
            net.minidev.json.JSONObject jsonObject = (net.minidev.json.JSONObject)JSONValue.parse(jsonString);
            System.out.println(jsonObject);
            
            net.minidev.json.JSONObject object = (net.minidev.json.JSONObject)jsonObject.get("result");
            System.out.println(object);
            
            net.minidev.json.JSONArray jsonArray = (net.minidev.json.JSONArray)object.get("users");
            System.out.println(jsonArray);
            
            object =  (net.minidev.json.JSONObject)jsonArray.get(0);
            System.out.println(object);
            
            System.out.println(object.get("username"));
        }
        
        // json-smart 4 Object
        @Test
        public void testJsonSmart4Object() {
            // Object -> String
            String bean2Json = JsonSmartUtil.bean2Json(person);
            System.out.println(bean2Json);
            
            // String -> Object
            Person json2Bean = JsonSmartUtil.json2Bean(bean2Json, Person.class);
            System.out.println(json2Bean);
        }
        
        // org.json 4 String
        @Test
        public void testOrgJson4String() {
            org.json.JSONObject jsonObject = new org.json.JSONObject(jsonString);
            System.out.println(jsonObject);
            
            org.json.JSONObject  object = (org.json.JSONObject)jsonObject.get("result");
            System.out.println(object);
            
            org.json.JSONArray jsonArray = (org.json.JSONArray)object.get("users");
            System.out.println(jsonArray);
            
            object = (org.json.JSONObject)jsonArray.get(0);
            System.out.println(object.get("username"));
        }
        
        // org.json默认不支持将JsonObject转为Java对象,需要自己增强
        @Test
        public void testOrgJson4Object() {
            // Object -> String
            String bean2Json = new CuitJSONObject(jsonString).toString();
            System.out.println(bean2Json);
            
            // String -> Object // 有问题
            person = (Person) new CuitJSONObject(bean2Json).toJavaBean(Person.class);
            System.out.println(person);
        }
        
        // json-simple 4 String
        @Test
        public void testJsonSimple4String() throws ParseException {
            JSONParser jsonParser = new JSONParser();
            org.json.simple.JSONObject  jsonObject = (org.json.simple.JSONObject)jsonParser.parse(jsonString);
            System.out.println(jsonObject);
            
            jsonObject = (org.json.simple.JSONObject)jsonObject.get("result");
            System.out.println(jsonObject);
            
            org.json.simple.JSONArray jsonArray = (org.json.simple.JSONArray)jsonObject.get("users");
            System.out.println(jsonArray);
            
            jsonObject = (org.json.simple.JSONObject)jsonArray.get(0);
            System.out.println(jsonObject.get("username"));
        }
        
        // Gson 4 String 
        @Test
        public void testGson4String() {
            // 格式化Json
            System.out.println(GsonUtil.jsonFormatter(jsonString));
            
            JsonParser jsonParser = new JsonParser();
            JsonObject jsonObject = (JsonObject)jsonParser.parse(jsonString);
            System.out.println(jsonObject);
            
            jsonObject = (JsonObject)jsonObject.get("result");
            System.out.println(jsonObject);
            
            JsonArray jsonArray =  (JsonArray)jsonObject.get("users");
            System.out.println(jsonArray);
            jsonObject = (JsonObject)jsonArray.get(0);
            
            // 最终输出的还是带有""包裹
            System.out.println(jsonObject.get("username"));
        }
        
        // Gson 4 Object 
        @Test
        public void testGson4Object() {
            // Object -> String
            String bean2Json = GsonUtil.bean2Json(person);
            System.out.println(bean2Json);
            
            // String -> Object
            person = GsonUtil.json2Bean(bean2Json, Person.class);
            System.out.println(person);
        }
        
        // Jackson 4 String
        @Test
        public void testJackson4String() throws IOException {
            ObjectMapper objectMapper = new ObjectMapper();
            
            // 方式一
            JsonNode rootNode = objectMapper.readTree(jsonString);
            System.out.println(rootNode);
            
            JsonNode resultPath = rootNode.path("result");
            System.out.println(resultPath);
            
            JsonNode usersPath = resultPath.path("users");
            System.out.println(usersPath);
            
            JsonNode userJsonNode = usersPath.get(0);
            System.out.println(userJsonNode);
            // 最终输出的还是带有""包裹
            System.out.println(userJsonNode.get("username"));
            
            // 方式二
            JsonNode resultJsonNode = rootNode.get("result");
            System.out.println(resultJsonNode);
            
            JsonNode usersJsonNode = resultJsonNode.get("users");
            System.out.println(usersJsonNode);
            
            JsonNode userNode = usersJsonNode.get(0);
            System.out.println(userNode.get("username"));
            
            // 返回""
            String result1 = resultJsonNode != null ? resultJsonNode.asText() : "";
            // 返回值
            String result2 = resultJsonNode != null ? resultJsonNode.toString() : "";
            System.out.println(result1);
            System.out.println(result2);
        }
        
        // Jackson 4 Object
        @Test
        public void testJackson4Object() {
            String bean2Json = JacksonUtil.bean2Json(person);
            System.out.println(bean2Json);
            
            person = JacksonUtil.json2Bean(bean2Json, Person.class);
            System.out.println(person);
        }
    }

[https_blog.csdn.net_suyimin2010_article_details_81406813]: https://blog.csdn.net/suyimin2010/article/details/81406813
[https_blog.csdn.net_DevolperFront_article_details_99515755]: https://blog.csdn.net/DevolperFront/article/details/99515755