json对象和java对象的相互转换方法(json-lib、jackson、fastjson、gson)
一 使用json-lib包下的JSONObject和JSONArray转换
代码如下：
package com.test.test; import java.util.ArrayList; import java.util.List; import com.cn.entity.User; import net.sf.json.JSONArray; import net.sf.json.JSONObject; /** * JSONObject和JSONArray * @author sun.kai * 2016年8月7日 */ public class TestJsonOne { public static void main(String[] args){ long time1 = System.currentTimeMillis(); // Map<String, Object> param = new HashMap<String,Object>(); // param.put("id", 1); // param.put("userName", "admin管理员"); // param.put("password", "admin123456"); // param.put("age", 25); // JSONObject jsonObject = JSONObject.fromObject(param); // System.out.println(jsonObject); // JSONArray jsonArray = JSONArray.fromObject(param); // System.out.println(jsonArray); List<User> list = new ArrayList<User>(); User user1 = new User(); user1.setId(1); user1.setUserName("admin管理员"); user1.setPassword("admin123456"); user1.setAge(25); testJsonObject(user1); list.add(user1); User user2 = new User(); user2.setId(2); user2.setUserName("海角七号"); user2.setPassword("海角七号123456"); user2.setAge(26); list.add(user2); testJsonArray(list); long time2 = System.currentTimeMillis(); System.out.println(time2-time1); } @SuppressWarnings("static-access") public static void testJsonObject(User user){ System.out.println("JSONObject测试"); /* * java对象转换成json对象 */ JSONObject jsonObject1 = JSONObject.fromObject(user); /* * json对象转成字符串 */ String jsonsString1 = jsonObject1.toString(); System.out.println(jsonObject1); System.out.println(jsonsString1); String jsonString2 = "{\"age\":25,\"id\":1,\"password\":\"admin123456\",\"userName\":\"admin管理员\"}"; /* * 字符串转成json对象 */ JSONObject jsonObject2 = JSONObject.fromObject(jsonString2); /* * json对象转成java对象 */ User user2 = (User) jsonObject2.toBean(jsonObject2,User.class); System.out.println(user2.getUserName()); /* * 获取json对象中的json对象数组 */ String jsonString3 = "{\"abc\":[{\"age\":25,\"id\":1,\"password\":\"admin123456\",\"userName\":\"admin管理员\"}," + "{\"age\":26,\"id\":2,\"password\":\"海角七号123456\",\"userName\":\"海角七号\"}" + "]}"; //字符串转成json对象 JSONObject jsonObject3 = JSONObject.fromObject(jsonString3); //获取json对象中的json对象数组 JSONArray jsonArray = jsonObject3.getJSONArray("abc"); System.out.println(jsonArray.toString()); } @SuppressWarnings("unchecked") public static void testJsonArray(List<User> userList){ System.out.println("JSONArray测试"); /* * java对象列表转换为json对象数组 */ JSONArray jsonArray1 = JSONArray.fromObject(userList); /* * json对象数组转成字符串 */ String arrayString1 = jsonArray1.toString(); System.out.println(jsonArray1); System.out.println(arrayString1); String arrayString2 = "[{\"age\":25,\"id\":1,\"password\":\"admin123456\",\"userName\":\"admin管理员\"},{\"age\":26,\"id\":2,\"password\":\"海角七号123456\",\"userName\":\"海角七号\"}]"; /* * 字符串转成json对象数组 */ JSONArray jsonArray2 = JSONArray.fromObject(arrayString2); /* * json对象数组转成java对象 */ List<User> users = (List<User>) JSONArray.toCollection(jsonArray2, User.class); for(User user : users){ System.out.println(user.getUserName()); } /* * 循环json对象数组，获取json对象 */ for(int i = 0;i<jsonArray2.size();i++){ JSONObject jsonObject = jsonArray2.getJSONObject(i); System.out.println(jsonObject); } } }
User实体类代码：
package com.cn.entity; import java.io.Serializable; public class User implements Serializable{ private static final long serialVersionUID = -154635138564326678L; private Integer id; private String userName; private String password; private Integer age; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName == null ? null : userName.trim(); } public String getPassword() { return password; } public void setPassword(String password) { this.password = password == null ? null : password.trim(); } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } }
执行后的结果：
JSONObject测试
{"age":25,"id":1,"password":"admin123456","userName":"admin管理员"}
{"age":25,"id":1,"password":"admin123456","userName":"admin管理员"}
admin管理员
[{"age":25,"id":1,"password":"admin123456","userName":"admin管理员"},{"age":26,"id":2,"password":"海角七号123456","userName":"海角七号"}]
JSONArray测试
[{"age":25,"id":1,"password":"admin123456","userName":"admin管理员"},{"age":26,"id":2,"password":"海角七号123456","userName":"海角七号"}]
[{"age":25,"id":1,"password":"admin123456","userName":"admin管理员"},{"age":26,"id":2,"password":"海角七号123456","userName":"海角七号"}]
admin管理员
海角七号
{"age":25,"id":1,"password":"admin123456","userName":"admin管理员"}
{"age":26,"id":2,"password":"海角七号123456","userName":"海角七号"}
686
二 使用jackson-databind包下的ObjectMapper
代码如下：
package com.test.test; import java.io.IOException; import java.util.ArrayList; import java.util.Arrays; import java.util.List; import com.cn.entity.User; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.ObjectMapper; /** * jackson是spring mvc内置的json转换工具 * @author sun.kai * 2016年8月7日 */ public class TestJsonTwo { public static void main(String[] args) throws JsonProcessingException{ long time1 = System.currentTimeMillis(); List<User> users = new ArrayList<User>(); User user1 = new User(); user1.setId(1); user1.setUserName("admin管理员"); user1.setPassword("admin123456"); user1.setAge(25); users.add(user1); User user2 = new User(); user2.setId(2); user2.setUserName("海角七号"); user2.setPassword("海角七号123456"); user2.setAge(26); users.add(user2); try { testObjectMapper(users); } catch (IOException e) { e.printStackTrace(); } long time2 = System.currentTimeMillis(); System.out.println(time2-time1); } public static void testObjectMapper(List<User> users) throws IOException{ ObjectMapper mapper = new ObjectMapper(); /* * java对象是一个集合 * 转成的字符串是json对象数组 */ String mapperString1 = mapper.writeValueAsString(users); System.out.println(mapperString1); /* * java对象不是一个集合 * 转成json对象字符串 */ String mapperString2 = mapper.writeValueAsString(users.get(0)); System.out.println(mapperString2); /* * json对象数组字符串转java对象集合 */ String jsonString1 = "[{\"age\":25,\"id\":1,\"password\":\"admin123456\",\"userName\":\"admin管理员\"},{\"age\":26,\"id\":2,\"password\":\"海角七号123456\",\"userName\":\"海角七号\"}]"; User[] userArray = mapper.readValue(jsonString1, User[].class); List<User> userList = Arrays.asList(userArray); for (User user : userList) { System.out.println(user.getUserName()); } /* * json对象字符串转java对象 */ String jsonString2 = "{\"age\":25,\"id\":1,\"password\":\"admin123456\",\"userName\":\"admin管理员\"}"; User user = mapper.readValue(jsonString2, User.class); System.out.println(user.getUserName()); } }
执行后的结果：
[{"id":1,"userName":"admin管理员","password":"admin123456","age":25},{"id":2,"userName":"海角七号","password":"海角七号123456","age":26}]
{"id":1,"userName":"admin管理员","password":"admin123456","age":25}
admin管理员
海角七号
admin管理员
784
三 使用fastjson
代码如下：
package com.test.test; import com.cn.entity.User; import java.util.ArrayList; import java.util.List; import java.util.Map; import com.alibaba.fastjson.JSON; import com.alibaba.fastjson.TypeReference; /** * fastjson是阿里做的国有开源Java工具包 * @author sun.kai * 2016年8月7日 */ public class TestJsonThree { public static void main(String[] args){ long time1 = System.currentTimeMillis(); List<User> users = new ArrayList<User>(); User user1 = new User(); user1.setId(1); user1.setUserName("admin管理员"); user1.setPassword("admin123456"); user1.setAge(25); users.add(user1); User user2 = new User(); user2.setId(2); user2.setUserName("海角七号"); user2.setPassword("海角七号123456"); user2.setAge(26); users.add(user2); testFastjson(users); long time2 = System.currentTimeMillis(); System.out.println(time2-time1); } @SuppressWarnings("unchecked") public static void testFastjson(List<User> users){ /* * java对象是一个集合 * 转成的字符串是json对象数组 */ String fastjsonString1 = JSON.toJSONString(users); System.out.println(fastjsonString1); /* * java对象不是一个集合 * 转成json对象字符串 */ String fastjsonString2 = JSON.toJSONString(users.get(0)); System.out.println(fastjsonString2); /* * json对象数组字符串转java对象集合 */ String jsonString1 = "[{\"age\":25,\"id\":1,\"password\":\"admin123456\",\"userName\":\"admin管理员\"},{\"age\":26,\"id\":2,\"password\":\"海角七号123456\",\"userName\":\"海角七号\"}]"; List<User> userList = JSON.parseArray(jsonString1, User.class); for (User user : userList) { System.out.println(user.getUserName()); } /* * json对象数组字符串转Map集合 */ List<Map<String, Object>> maps = JSON.parseObject(jsonString1,new TypeReference<List<Map<String,Object>>>(){}); System.out.println(maps); for (Map<String, Object> map : maps) { System.out.println(map.get("userName")); } /* * json对象字符串转java对象 */ String jsonString2 = "{\"age\":25,\"id\":1,\"password\":\"admin123456\",\"userName\":\"admin管理员\"}"; User user = JSON.parseObject(jsonString2, User.class); System.out.println(user.getUserName()); /* * json对象字符串转Map */ Map<String, Object> map = JSON.parseObject(jsonString2, Map.class); System.out.println(map); System.out.println(map.get("userName")); } }
执行结果：
[{"age":25,"id":1,"password":"admin123456","userName":"admin管理员"},{"age":26,"id":2,"password":"海角七号123456","userName":"海角七号"}]
{"age":25,"id":1,"password":"admin123456","userName":"admin管理员"}
admin管理员
海角七号
[{id=1, age=25, userName=admin管理员, password=admin123456}, {id=2, age=26, userName=海角七号, password=海角七号123456}]
admin管理员
海角七号
admin管理员
{id=1, age=25, userName=admin管理员, password=admin123456}
admin管理员
338
四 使用Google的Gson
代码如下：
package com.test.test; import com.cn.entity.User; import com.google.gson.Gson; import com.google.gson.reflect.TypeToken; import java.util.ArrayList; import java.util.List; import java.util.Map; /** * google的gson * https://mvnrepository.com/artifact/com.google.code.gson/gson * @author sun.kai * 2016年8月7日 */ public class TestJsonFour { public static void main(String[] args){ long time1 = System.currentTimeMillis(); List<User> users = new ArrayList<User>(); User user1 = new User(); user1.setId(1); user1.setUserName("admin管理员"); user1.setPassword("admin123456"); user1.setAge(25); users.add(user1); User user2 = new User(); user2.setId(2); user2.setUserName("海角七号"); user2.setPassword("海角七号123456"); user2.setAge(26); users.add(user2); testGson(users); long time2 = System.currentTimeMillis(); System.out.println(time2-time1); } @SuppressWarnings("unchecked") public static void testGson(List<User> users){ /* * 创建Gson对象 */ Gson gson = new Gson(); /* * 获得泛型参数的类型 */ java.lang.reflect.Type type = new TypeToken<List<User>>() {}.getType(); /* * java对象是一个集合 * 转成的字符串是json对象数组 */ String gsonString1 = gson.toJson(users); System.out.println(gsonString1); /* * java对象不是一个集合 * 转成json对象字符串 */ String gsonString2 = gson.toJson(users.get(0)); System.out.println(gsonString2); /* * json对象数组字符串转java对象集合 */ String jsonString1 = "[{\"age\":25,\"id\":1,\"password\":\"admin123456\",\"userName\":\"admin管理员\"},{\"age\":26,\"id\":2,\"password\":\"海角七号123456\",\"userName\":\"海角七号\"}]"; List<User> userList = gson.fromJson(jsonString1, type); for (User user : userList) { System.out.println(user.getUserName()); } /* * json对象数组字符串转Map集合 */ List<Map<String, Object>> maps = gson.fromJson(jsonString1,new TypeToken<List<Map<String, Object>>>() {}.getType()); System.out.println(maps); for (Map<String, Object> map : maps) { System.out.println(map.get("userName")); } /* * json对象字符串转java对象 */ String jsonString2 = "{\"age\":25,\"id\":1,\"password\":\"admin123456\",\"userName\":\"admin管理员\"}"; User user = gson.fromJson(jsonString2, User.class); System.out.println(user.getUserName()); /* * json对象字符串转Map */ Map<String, Object> map = gson.fromJson(jsonString2, Map.class); System.out.println(map); System.out.println(map.get("userName")); } }
执行结果：
[{"id":1,"userName":"admin管理员","password":"admin123456","age":25},{"id":2,"userName":"海角七号","password":"海角七号123456","age":26}]
{"id":1,"userName":"admin管理员","password":"admin123456","age":25}
admin管理员
海角七号
[{age=25.0, id=1.0, password=admin123456, userName=admin管理员}, {age=26.0, id=2.0, password=海角七号123456, userName=海角七号}]
admin管理员
海角七号
admin管理员
{age=25.0, id=1.0, password=admin123456, userName=admin管理员}
admin管理员
336
