各种类型的对象的输出格式总结

引入jar包

<dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.58</version> </dependency>

ObjectOutputFormat.java

package com.example.demo.util; import com.alibaba.fastjson.JSON; import com.alibaba.fastjson.JSONArray; import com.alibaba.fastjson.JSONObject; import com.example.demo.entity.User; import java.util.ArrayList; import java.util.Arrays; import java.util.List; /** * 各种类型的对象的输出格式总结 */ public class ObjectOutputFormat { /** * int数组输出格式 * * [1, 2, 3] */ public static void test3() { int[] nums = {1,2,3}; System.out.println(Arrays.toString(nums)); } /** * JSONObject以jsonString形式把存储的int数组输出格式 * * { * "msg":"success", * "code":"200", * "data":[ * 1, * 2, * 3 * ] * } */ public static void test4() { //1. 初始化数据 JSONObject jsonObject = new JSONObject(); jsonObject.put("code", "200"); jsonObject.put("msg", "success"); int[] nums = {1,2,3}; jsonObject.put("data", nums); //2. 对象转json字符串 String jsonString = JSON.toJSONString(jsonObject); //3. 输出 System.out.println(jsonString); } /** * JSONArray中存储的int数组输出格式 * * [1,2,3] */ public static void test5() { //1. 初始化数据 int[] nums = {1,2,3}; JSONObject jsonObject = new JSONObject(); jsonObject.put("code", "200"); jsonObject.put("msg", "success"); jsonObject.put("data", nums); //2. 对象转json字符串 String jsonString = JSON.toJSONString(jsonObject); //3. 解析jsonString JSONObject newJsonObject = JSON.parseObject(jsonString); //4. 获取JSONArray数据 JSONArray jsonArray = newJsonObject.getJSONArray("data"); //3. 输出 System.out.println(jsonArray); } /** * 对象User输出格式 * * User { * id=1, * name='刘德华' * } */ public static void test1() { User u = new User(1,"刘德华"); System.out.println(u.toString()); } /** * 对象User的json格式表示 * * { * "id":1, * "name":"刘德华" * } */ public static void test2() { User u = new User(1,"刘德华"); System.out.println(JSON.toJSON(u)); System.out.println(JSON.toJSONString(u)); } /** * List<User>输出格式 * * [ * User{ * id=1, * name='刘德华' * }, * User{ * id=1, * name='林峰' * }, * User{ * id=1, * name='毛不易' * } * ] */ public static void test6() { //1. 创建User集合 List<User> users = new ArrayList<>(); User u1 = new User(1,"刘德华"); User u2 = new User(1,"林峰"); User u3 = new User(1,"毛不易"); users.add(u1); users.add(u2); users.add(u3); //2. 输出List<User> System.out.println(users); } /** * List<User>转json 字符串的输出格式 * * [ * { * "id":1, * "name":"刘德华" * }, * { * "id":1, * "name":"林峰" * }, * { * "id":1, * "name":"毛不易" * } * ] */ public static void test9() { //1. 创建User集合 List<User> users = new ArrayList<>(); User u1 = new User(1,"刘德华"); User u2 = new User(1,"林峰"); User u3 = new User(1,"毛不易"); users.add(u1); users.add(u2); users.add(u3); //2. jsonString String jsonString = JSONArray.toJSONString(users); System.out.println("方式一：" + jsonString); jsonString = JSON.toJSONString(users); System.out.println("方式二：" + jsonString); } /** * JSONObject以json字符串的形式输出User数组 * * { * "msg":"success", * "code":"200", * "data":[ * { * "id":1, * "name":"刘德华" * }, * { * "id":1, * "name":"林峰" * }, * { * "id":1, * "name":"毛不易" * }] * } */ public static void test7() { //1. 创建User集合 List<User> users = new ArrayList<>(); User u1 = new User(1,"刘德华"); User u2 = new User(1,"林峰"); User u3 = new User(1,"毛不易"); users.add(u1); users.add(u2); users.add(u3); //2. 创建JSONObject JSONObject jsonObject = new JSONObject(); jsonObject.put("code", "200"); jsonObject.put("msg", "success"); jsonObject.put("data", users); System.out.println("jsonObject = " + jsonObject); //3. 创建jsonString String jsonString = JSON.toJSONString(jsonObject); System.out.println(jsonString); } /** * User对象在JSONArray中的输出格式 * * [ * { * "name":"刘德华", * "id":1 * }, * { * "name":"林峰", * "id":1 * }, * { * "name":"毛不易", * "id":1 * } * ] */ public static void test8() { //1. 创建User集合 List<User> users = new ArrayList<>(); User u1 = new User(1,"刘德华"); User u2 = new User(1,"林峰"); User u3 = new User(1,"毛不易"); users.add(u1); users.add(u2); users.add(u3); //2. 创建JSONObject JSONObject jsonObject = new JSONObject(); jsonObject.put("code", "200"); jsonObject.put("msg", "success"); jsonObject.put("data", users); //3. 创建jsonString String jsonString = JSON.toJSONString(jsonObject); //4. 解析 JSONObject newJsonObject = JSON.parseObject(jsonString); //5. 创建JSONArray JSONArray jsonArray = newJsonObject.getJSONArray("data"); //6. 输出 System.out.println(jsonArray); } public static void main(String[] args) { System.out.println("\nint数组输出格式："); test3(); System.out.println("\nJSONObject以jsonString形式把存储的int数组输出格式: "); test4(); System.out.println("\nJSONArray中存储的int数组输出格式: "); test5(); System.out.println("对象User输出格式: "); test1(); System.out.println("\n对象User的json格式表示: "); test2(); System.out.println("\nList<User>输出格式: "); test6(); System.out.println("\nJSONObject以json字符串的形式输出User数组: "); test7(); System.out.println("\nUser对象在JSONArray中的输出格式: "); test8(); System.out.println("\nList<User>转json 字符串的输出格式: "); test9(); } }

User.java

package com.example.demo.entity; public class User { private Integer id; private String name; public User() { } public User(Integer id, String name) { this.id = id; this.name = name; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "User{" + "id=" + id + ", name='" + name + '\'' + '}'; } }

输出

int数组输出格式： [1, 2, 3] JSONObject以jsonString形式把存储的int数组输出格式: {"msg":"success","code":"200","data":[1,2,3]} JSONArray中存储的int数组输出格式: [1,2,3] 对象User输出格式: User{id=1, name='刘德华'} 对象User的json格式表示: {"name":"刘德华","id":1} {"id":1,"name":"刘德华"} List<User>输出格式: [User{id=1, name='刘德华'}, User{id=1, name='林峰'}, User{id=1, name='毛不易'}] JSONObject以json字符串的形式输出User数组: jsonObject = {"msg":"success","code":"200","data":[{"id":1,"name":"刘德华"},{"id":1,"name":"林峰"},{"id":1,"name":"毛不易"}]} {"msg":"success","code":"200","data":[{"id":1,"name":"刘德华"},{"id":1,"name":"林峰"},{"id":1,"name":"毛不易"}]} User对象在JSONArray中的输出格式: [{"name":"刘德华","id":1},{"name":"林峰","id":1},{"name":"毛不易","id":1}] List<User>转json 字符串的输出格式: 方式一：[{"id":1,"name":"刘德华"},{"id":1,"name":"林峰"},{"id":1,"name":"毛不易"}] 方式二：[{"id":1,"name":"刘德华"},{"id":1,"name":"林峰"},{"id":1,"name":"毛不易"}]