JSON資料處理
阿新 • • 發佈：2021-08-20
JSON資料處理
JSON資料處理
1.json的資料格式
1.1 陣列格式
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <script type="text/javascript"> /* * 定義json的格式陣列格式 * 中括號包裹，陣列的元素的資料型別沒有限制 * 元素之間，逗號分開 * */ var jsonArray = ["k1","k2",100,9.9,true]; //訪問資料元素，通過索引訪問 console.log(jsonArray[1]); //遍歷陣列，取出陣列中的元素 for(var i=0;i<jsonArray.length; i++){ console.log(jsonArray[i]); } </script> </head> <body> </body> </html>
1.2 物件格式
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <script type="text/javascript"> /* * 定義json的物件格式 * 大括號包裹，定義鍵值對，鍵必須是字串型別，值得資料型別不限制 * 鍵值對之間，是冒號分開 * 每個鍵值對之間，逗號分開 * */ var jsonObject={ "k1":"v1", "k2":"v2", "k3":100, "k4":9.9, "k5":true } //取出鍵值對，鍵找值的方式 console.log(jsonObject.k1); console.log(jsonObject.k2); console.log(jsonObject.k3); console.log(jsonObject.k4); console.log(jsonObject.k5); </script> </head> <body> </body> </html>
1.3 資料巢狀物件
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>json資料的巢狀</title> <script type="text/javascript"> /* * json資料的元素是物件 * */ var jsonArray = [ {"name":"張三","age":20}, {"name":"李四","age":22} ] //取出需要的資料 ，李四 22 console.log( jsonArray[1].name+"----"+jsonArray[1].age); //遍歷資料，取出陣列中的元素 for (var i = 0; i < jsonArray.length; i++) { console.log(jsonArray[i].name +"----"+jsonArray[i].age); } </script> </head> <body> </body> </html>
1.4 物件巢狀資料
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript">
/*
* json資料是物件，物件值是陣列
* */
var jsonObject = {
"k1": ["北京","上海","廣州","深圳"],
"k2": ["中國","美國","英國","法國"]
}
//取出上海
console.log(jsonObject.k1[1]);
//分別取出k1和k2鍵的陣列，遍歷
for (var i = 0; i < jsonObject.k1.length; i++) {
console.log(jsonObject.k1[i]);
}
console.log("============================================")
for (var i = 0; i < jsonObject.k2.length; i++) {
console.log(jsonObject.k2[i]);
}
</script>
</head>
<body>
</body>
</html>
1.5 json巢狀
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>json資料的巢狀</title>
<script type="text/javascript">
/*
* json的資料巢狀，你中有我，我中有你
* json的資料本質是物件
* 物件是的鍵是字串，物件的值是陣列
* 陣列的元素是物件
* */
var json = {
//鍵是k1，值是陣列，陣列的元素是物件
"k1":[
//陣列的元素是兩個物件
{"name":"張三","age":20},
{"name":"李四","age":21},
],
"k2":[
//陣列的元素是兩個物件
{"name":"王五","age":23},
{"name":"趙六","age":24},
],
}
//取出資料 李四 21
console.log(json.k1[1].name+"---"+json.k1[1].age);
//遍歷k2鍵對應的陣列
for (var i = 0; i <json.k2.length ; i++) {
console.log(json.k2[i].name+"---"+json.k2[i].age);
}
</script>
</head>
<body>
</body>
</html>
2.fastjson
它可以解析JSON格式的字串，支援將Java Bean序列化為JSON字串，也可以從JSON字串反序列化到Java Bean。
@Data
public class Student {
private Integer id;
private String name;
private Integer age;
private String email;
private Date birthday;
}
2.1 Java物件序列化到Json
//java中的物件，Student物件，序列化Json格式字串
@Test
public void testObjectToJson(){
Student student = new Student();
student.setId(1);
student.setName("張三");
student.setAge(20);
student.setEmail("[email protected]");
student.setBirthday(getDate());
//student物件轉成json格式的字串
//呼叫靜態方法，傳遞要抓換的物件
String jsonString = JSON.toJSONString(student);
System.out.println(jsonString);
//{"age":20,"birthday":1629451099346,"email":"[email protected]","id":1,"name":"張三"}
}
{
"age":20,
"birthday":1629451099346,
"email":"[email protected]",
"id":1,
"name":"張三"
}
//java中的集合List，序列化為Json格式字串
@Test
public void testListToJson(){
//集合List，儲存Student物件
ArrayList<Student> list = new ArrayList<>();
Student student1 = new Student();
student1.setId(1);
student1.setName("張三");
student1.setAge(20);
student1.setEmail("[email protected]");
student1.setBirthday(getDate());
Student student2 = new Student();
student2.setId(2);
student2.setName("趙四");
student2.setAge(25);
student2.setEmail("[email protected]");
student2.setBirthday(getDate());
//student物件儲存到集合中
list.add(student1);
list.add(student2);
//List集合，序列化為Json格式字串
String jsonString = JSON.toJSONString(list);
System.out.println(jsonString);
//轉後的結果是陣列，陣列的元素是物件
//[{"age":20,"birthday":1629451016542,"email":"[email protected]","id":1,"name":"張三"},
// {"age":25,"birthday":1629451016542,"email":"[email protected]","id":2,"name":"趙四"}]
}
[
{"age":20,"birthday":1629451016542,"email":"[email protected]","id":1,"name":"張三"},
{"age":25,"birthday":1629451016542,"email":"[email protected]","id":2,"name":"趙四"}
]
//java中的集合Map,序列化為Json格式字串
@Test
public void testMapToJson(){
//建立map集合，鍵為字串型別，值為Student物件
HashMap<String, Student> map = new HashMap<>();
Student student1 = new Student();
student1.setId(1);
student1.setName("張三");
student1.setAge(20);
student1.setEmail("[email protected]");
student1.setBirthday(getDate());
Student student2 = new Student();
student2.setId(2);
student2.setName("趙四");
student2.setAge(25);
student2.setEmail("[email protected]");
student2.setBirthday(getDate());
//Map集合儲存Student物件
map.put("student1",student1);
map.put("student2",student2);
String jsonString = JSON.toJSONString(map);
System.out.println(jsonString);
//json格式字串是物件，物件中有兩個鍵，鍵對應的值是Student物件
//{"student2":{"age":25,"birthday":1629451782886,"email":"[email protected]","id":2,"name":"趙四"},
// "student1":{"age":20,"birthday":1629451782886,"email":"[email protected]","id":1,"name":"張三"}}
}
{
"student2":{"age":25,"birthday":1629451782886,"email":"[email protected]","id":2,"name":"趙四"},
"student1":{"age":20,"birthday":1629451782886,"email":"[email protected]","id":1,"name":"張三"}
}
2.2 Json反序列化到java物件
//Json格式字串，反序列化到Java物件
@Test
public void testJsonToObject(){
String jsonString = "{\"age\":20,\"birthday\":1629451099346,\"email\":\"[email protected]\",\"id\":1,\"name\":\"張三\"}";
//Json類的靜態方法 parseObject
//傳遞要反序列化的Json字串，傳遞Java物件的class物件
Student student=JSON.parseObject(jsonString,Student.class);
System.out.println(student);
}
//Json格式字串，反序列化到List集合
@Test
public void testJsonToList(){
String jsonString = "[{\"age\":20,\"birthday\":1629451016542,\"email\":\"[email protected]\",\"id\":1,\"name\":\"張三\"},\n" +
" {\"age\":25,\"birthday\":1629451016542,\"email\":\"[email protected]\",\"id\":2,\"name\":\"趙四\"}]";
//Json類的靜態方法 parseArray
//傳遞Json格式的字串，傳遞轉換後的集合的泛型的class物件
List<Student> list = JSON.parseArray(jsonString, Student.class);
list.forEach(System.out::println);
}
//Json格式字串，反序列化到Map集合
@Test
public void testJsonToMap(){
String jsonString = "{\"student2\":{\"age\":25,\"birthday\":1629455067665,\"email\":\"[email protected]\",\"id\":2,\"name\":\"趙四\"}," +
"\"student1\":{\"age\":20,\"birthday\":1629455067665,\"email\":\"[email protected]\",\"id\":1,\"name\":\"張三\"}}";
//json類的靜態方法，parseObject
//直接進行反序列化，Map集合是沒有泛型的，泛型沒有事不安全的
//轉後的集合，必須有泛型
//呼叫parseObject，傳遞引數，TypeReference型別
//將Map中所有的鍵存入到set集合中。因為set具備迭代器。所有可以迭代方式取出所有的鍵，再根據get方法。獲取每一個鍵對應的值。
//keySet():迭代後只能通過get()取key
Map<String, Student> map = JSON.parseObject(jsonString, new TypeReference<Map<String, Student>>() {});
for (String key : map.keySet()){
System.out.println(key+":"+map.get(key));
}
}