舉例講授Java的Jackson庫中ObjectMapper類的應用。本站提示廣大學習愛好者:(舉例講授Java的Jackson庫中ObjectMapper類的應用)文章只能為提供參考,不一定能成為您想要的結果。以下是舉例講授Java的Jackson庫中ObjectMapper類的應用正文
ObjectMapper類是Jackson庫的重要類。它供給一些功效將轉換成Java對象婚配JSON構造,反之亦然。它應用JsonParser和JsonGenerator的實例完成JSON現實的讀/寫。
類聲明
以下是org.codehaus.jackson.map.ObjectMapper類的聲明:
public class ObjectMapper extends ObjectCodec implements Versioned
嵌套類
例子
測試類根本代碼以下
/* * @project java * @package * @file Jackson.java * @version 1.0 */ public class Jackson { /* * * Class Descripton goes here. * * @class Jackson * @version 1.0 */ public static JsonGenerator jsonGenerator = null; private static ObjectMapper mapper = new ObjectMapper(); public static void main(String[] args) { Student student = new Student(); student.setIsstudent(true); student.setUid(1000); student.setUname("xiao liao"); student.setUpwd("123"); student.setNumber(12); Map<String, Student> stuMap = new HashMap<String, Student>(); stuMap.put("1", student); stuMap.put("2", student); List<Object> stuList = new ArrayList<Object>(); List<Student> stuList1 = new ArrayList<Student>(); stuList1.add(student); student= new Student(); student.setIsstudent(false); student.setUid(200); student.setUname("xiao mi"); stuList1.add(student); stuList.add(student); stuList.add("xiao xin"); stuList.add("xiao er"); stuList.add(stuMap); //readJson2List(); try { //readJson2Array(); //writeArray2Json(array); //writeJson2List(); //writeEntity2Json(student); writeJson2Entity(); //writeMap2Json(stuMap); //writeList2Json(stuList1); } catch (IOException e) { e.printStackTrace(); } } /** * * <code>writeEntity2Json</code> * @description: TODO(實體類轉換成json) * @param object * @throws IOException */ public static void writeEntity2Json(Object object) throws IOException { mapper.writeValue( new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aa.txt"),object ); mapper.writeValue( System.out,object ); } /** * * <code>writeArray2Json</code> * @description: TODO(數組轉換成json數組) * @param object * @throws IOException */ public static void writeArray2Json(Object object) throws IOException { // writeValue具有和writeObject雷同的功效 mapper.writeValue( new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aa.txt"),object ); mapper.writeValue(System.out,object ); } /** * * <code>writeMap2Json</code> * @description: TODO(map對象轉換成json對象) * @param object * @throws IOException * @since 2011-11-8 廖益平 */ public static void writeMap2Json(Object object) throws IOException { System.out.println("應用ObjectMapper-----------"); // writeValue具有和writeObject雷同的功效 System.out.println("==>"+mapper.writeValueAsString(object)); mapper.writeValue( new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aamap.txt"),object ); mapper.writeValue( System.out , object ); } /** * * <code>writeList2Json</code> * @description: TODO(list轉換成json) * @param object * @throws IOException */ public static void writeList2Json(Object object) throws IOException { System.out.println("==>"+mapper.writeValueAsString(object)); mapper.writeValue( new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aamap.txt"),object ); mapper.writeValue( System.out , object ); } /** * * <code>writeJson2Entity</code> * @description: TODO(json轉換成實體) * @throws IOException */ public static void writeJson2Entity() throws IOException { System.out.println("json串轉換成entity-------------"); // File file = new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aa.txt"); // FileInputStream inputStream = new FileInputStream(file); // Student student = mapper.readValue(inputStream,Student.class); // System.out.println(student.toString()); //英俊輸入 //mapper.defaultPrettyPrintingWriter().writeValueAsString(value); String json = "{\"uid\":1000,\"uname\":\"xiao liao\",\"upwd\":\"123\",\"number\":12.0,\"isstudent\":true}"; Student student1 = mapper.readValue(json,Student.class); System.out.println("json2:"+student1.toString()); } /** * * <code>writeJson2List</code> * @description: TODO(json特地list對象) * @throws IOException */ public static void writeJson2List() throws IOException { System.out.println("json串轉換成entity-------------"); File file = new File("D:\\developSoft\\aaadowload\\testjson1\\lib\\aa.txt"); FileInputStream inputStream = new FileInputStream(file); Student student = mapper.readValue(inputStream,Student.class); System.out.println(student.toString()); String json = "[{\"uid\":1000,\"uname\":\"xiao liao\",\"upwd\":\"123\",\"number\":12.0,\"isstudent\":true},{\"uid\":200,\"uname\":\"xiao mi\",\"upwd\":null,\"number\":0.0,\"isstudent\":false}]"; List<LinkedHashMap<String, Object>> s= mapper.readValue(json,List.class); for (int i = 0; i < s.size(); i++) { LinkedHashMap<String, Object> link = s.get(i); Set<String> key = link.keySet(); for (Iterator iterator = key.iterator(); iterator.hasNext();) { String string = (String) iterator.next(); System.out.println(string+"==>"+link.get(string)); } System.out.println("json:"+i+""+s.get(i).toString()); } } /** * JSON轉換為List對象 */ public static void readJson2List() { String json = "[{\"uid\":1,\"uname\":\"www\",\"number\":234,\"upwd\":\"456\"}," + "{\"uid\":5,\"uname\":\"tom\",\"number\":3.44,\"upwd\":\"123\"}]"; try { List<LinkedHashMap<String, Object>> list = mapper.readValue( json, List.class); System.out.println(list.size()); for (int i = 0; i < list.size(); i++) { Map<String, Object> map = list.get(i); Set<String> set = map.keySet(); for (Iterator<String> it = set.iterator(); it.hasNext();) { String key = it.next(); System.out.println(key + ":" + map.get(key)); } } } catch (JsonParseException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } /** * JSON轉換為List對象 */ public static void readJson2Array() { String json = "[{\"uid\":1,\"uname\":\"www\",\"number\":234,\"upwd\":\"456\"}," + "{\"uid\":5,\"uname\":\"tom\",\"number\":3.44,\"upwd\":\"123\"}]"; try { Student[] students = mapper.readValue(json, Student[].class); for (Student student : students) { System.out.println(">"+student.toString()); } } catch (JsonParseException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
打印成果 :
串轉換成entity------------- json2:uid=1000,name=xiao liao,upwd=123,number=12.0,isStudent=true writeMap2Json ----------- {"2":{"uid":1000,"uname":"xiao liao","upwd":"123","number":12.0,"isstudent":true},"1":{"uid":1000,"uname":"xiao liao","upwd":"123","number":12.0,"isstudent":true}} readJson2Array------------------ >uid=1,name=www,upwd=456,number=234.0,isStudent=false >uid=5,name=tom,upwd=123,number=3.44,isStudent=false writeMap2Json ----------- {"2":{"uid":1000,"uname":"xiao liao","upwd":"123","number":12.0,"isstudent":true},"1":{"uid":1000,"uname":"xiao liao","upwd":"123","number":12.0,"isstudent":true}}
年夜家逐一本身嘗嘗吧 ,下面也是我的測試代碼