1.json傳遞中和javaBean對象的關系

== 打印出來的字符串，對象和鍵值集合用{}, 數組和用[]==

2.json的轉換

總測試類:以下轉換都為單元測試方法

public class ObjectMapperTest {private ObjectMapper mapper = new ObjectMapper(); }

<1>json和對象的轉換

/*1.User對象轉json, json轉User對象json字符串 = {"name":"張三","age":23}user對象 = User{name='張三', age=23}*/@Testpublic void test01() throws Exception {//對象轉化為Json字符串Student student = new Student("張三", 20, new Date());String json = mapper.writeValueAsString(student);System.out.println("json字符串：" + json);//json轉化為對象Student stu = mapper.readValue(json, Student.class);System.out.println("java對象：" + stu);}打印結果: --------------------------------------------------------------------- json字符串：{"name":"張三","age":20} java對象：Student{name='張三', age=20, birthday=null}

<2>json和map的轉換

/*2.map<String,String>轉json, json轉map<String,String>json字符串 = {"姓名":"張三","性別":"男"}map對象 = {姓名=張三, 性別=男}*/@Testpublic void test02() throws Exception {//對象轉化為Json字符串HashMap<String,String> map = new HashMap<>();map.put("姓名","張三");map.put("年齡","20");String json = mapper.writeValueAsString(map);System.out.println("json字符串：" + json);//json轉化為對象HashMap hashMap = mapper.readValue(json, HashMap.class);System.out.println(hashMap);}打印結果: --------------------------------------------------------------------- json字符串：{"姓名":"張三","年齡":"20"} {姓名=張三, 年齡=20} /*3.map<String,User>轉json, json轉map<String,User>json字符串 = {"黑馬一班":{"name":"張三","age":23},"黑馬二班":{"name":"李四","age":24}}map對象 = {黑馬一班=User{name='張三', age=23}, 黑馬二班=User{name='李四', age=24}}*/@Testpublic void test03() throws Exception {//對象轉化為Json字符串HashMap<String, Student> map = new HashMap<>();Student student1 = new Student("張三", 20);Student student2 = new Student("李四", 21);map.put("一班",student1);map.put("二班",student2);String json = mapper.writeValueAsString(map);System.out.println("json字符串：" + json);//json轉化為對象HashMap<String,Student> hashMap = mapper.readValue(json, new TypeReference<HashMap<String, Student>>() {});System.out.println(hashMap);}打印結果: --------------------------------------------------------------------- json字符串：{"一班":{"name":"張三","age":20},"二班":{"name":"李四","age":21}} {一班=Student{name='張三', age=20, birthday=null}, 二班=Student{name='李四', age=21, birthday=null}}

<3>json和List的轉換

/*4.List<String>轉json, json轉 List<String>json字符串 = ["張三","李四"]list對象 = [張三, 李四]*/@Testpublic void test04() throws Exception {//對象轉化為Json字符串List<String> list = new ArrayList<>();list.add("張三");list.add("李四");String json = mapper.writeValueAsString(list);System.out.println("json字符串：" + json);//json轉化為對象List list1 = mapper.readValue(json, List.class);System.out.println(list1);}打印結果: ----------------------------------------------------------------------------- json字符串：["張三","李四"] [張三, 李四] /*5.List<User>轉json, json轉List<User>json字符串 = [{"name":"張三","age":23},{"name":"李四","age":24}]list對象 = [User{name='張三', age=23}, User{name='李四', age=24}]*/@Testpublic void test05() throws Exception {//對象轉化為Json字符串ArrayList<Student> list = new ArrayList<>();Student student1 = new Student("張三", 20);Student student2 = new Student("李四", 21);list.add(student1);list.add(student2);String json = mapper.writeValueAsString(list);System.out.println(json);//json轉化為對象//匿名內部類可根據我們指定的類型進行轉換ArrayList<Student> list1 = mapper.readValue(json,new TypeReference<ArrayList<Student>>(){} );System.out.println(list1);}打印結果: ------------------------------------------------------------------------------- [{"name":"張三","age":20},{"name":"李四","age":21}] [Student{name='張三', age=20, birthday=null}, Student{name='李四', age=21, birthday=null}] 創作挑戰賽新人創作獎勵來咯，堅持創作打卡瓜分現金大獎

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