問題描述：
首先我遇到的第一個問題就是，在給前端傳json數據。
我們前后端數據通信一般使用json格式的數據來傳遞， 那么后端如何給前端傳值，以及我們有那么多的數據類型，都是怎么傳遞的呢？
public class JackSonTest {
//json傳送一個實例對象
@Test
public void test1() throws Exception {
Person p = new Person();
p.setName("Jack");
p.setAge(22);
p.setGender("男");
//2.創建ObjectMapper
ObjectMapper mapper = new ObjectMapper();
//3.轉換
String s = mapper.writeValueAsString(p);
System.out.println(s);
//寫入到指定文件中
//mapper.writeValue(new File("d://a.txt"),p);
//寫入到指定流中
//mapper.writeValue(new FileOutputStream("d://a.txt"),p);
//mapper.writeValue(new FileWriter("d://a.txt"),p);
}
@Test
public void test2() throws JsonProcessingException {
Person p = new Person();
p.setName("Rose");
p.setAge(22);
p.setGender("女");
p.setBirthday(new Date());
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(p);
System.out.println(json);
}
//json傳送一個list
@Test
public void test3() throws JsonProcessingException {
Person p = new Person();
p.setName("Haker");
p.setAge(33);
p.setGender("男");
p.setBirthday(new Date());
Person p1 = new Person();
p1.setName("Shelly");
p1.setAge(33);
p1.setGender("男");
p1.setBirthday(new Date());
Person p2 = new Person();
p2.setName("Bale");
p2.setAge(33);
p2.setGender("男");
p2.setBirthday(new Date());
List<Person> list = new ArrayList<>();
list.add(p);
list.add(p1);
list.add(p2);
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(list);
System.out.println(json);
}
//json傳送一個map
@Test
public void test4() throws JsonProcessingException {
Map<String, Object> map = new HashMap<String, Object>();
map.put("name", "Magie");
map.put("age", 22);
map.put("gender", "女");
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(map);
System.out.println(json);
}
//json字符串轉換為一個實例對象
@Test
public void test5() throws JsonProcessingException {
String js = "{\"gender\":\"男\",\"name\":\"Tokky\",\"age\":22}";
ObjectMapper mapper = new ObjectMapper();
Person person = mapper.readValue(js, Person.class);
System.out.println(person);
}
}
問題解決：
@Controller
public class FileController {
@ResponseBody
@RequestMapping("/test")
public String file() throws JsonProcessingException {
List<MyFile> list = new ArrayList<>(10);
list.add(new MyFile("01", new Date()));
list.add(new MyFile("02", new Date()));
list.add(new MyFile("03", new Date()));
list.add(new MyFile("04", new Date()));
list.add(new MyFile("05", new Date()));
list.add(new MyFile("06", new Date()));
list.add(new MyFile("07", new Date()));
list.add(new MyFile("08", new Date()));
list.add(new MyFile("09", new Date()));
list.add(new MyFile("10", new Date()));
list.add(new MyFile("11", new Date()));
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(list);
return json;
}
}
總結：
通過查閱資料學習；
解析，轉換josn數據需要依賴第三方jar包：Jackson Databind、Jackson Core、Jackson Annotations
1.准備json數據，（對象、集合、字符串）
2.創建ObjectMapper對象
3.調用writeValueAsString方法
如果是解析json字符串調用readValue方法 |
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