关于在controller中json数据与对象,map,list的相互转换
步骤：
1.导入jackson相关jar包
- jackson-annotations.jar
- jackson-core.jar
- jackson-databind.jar
com.fasterxml.jackson.core jackson-core 2.7.3 com.fasterxml.jackson.core jackson-databind 2.7.3 com.fasterxml.jackson.core jackson-annotations 2.7.3 --------------------------------------
2.创建jackson的核心对象：ObjectMapper
ObjectMapper mapper = new ObjectMapper();
3.调用mapper的相关方法
对象转json
User user = new User("Tom","沈阳")； String json = mapper.writeValueAsString(user); System.out.print(json); //输出：
Map<String,String>转json
HashMap<String,String> map = new HashMap<String,String>();
map.put("name","Kris");
map.put("city","沈阳");
String json = mapper.writeValueAsString(map);
System.out.print(json); //输出：{"city":"沈阳","name":"Kris"} （HashMap是无序的）
Map<String,Object>转json
Map<String,User> map = new HashMap<String,User>(); map1.put("01",new User("Tom","沈阳")); map1.put("02",new User("Kris","上海")); String json = mapper.writeValueAsString(map1); System.out.println(json); 输出： { "01":{"name":"Tom","city":"沈阳"}, "02":{"name":"Kris","city":"上海"} }
ArrayList转为json
ArrayList al = new ArrayList(); al.add("Tom"); al.add("沈阳"); String json = mapper.writeValueAsString(al); System.out.print(json); //输出：["TOM","SHENYANG"]
ArrayList转为json
ArrayList al = new ArrayList(); al.add(new User("Tom","沈阳")); al.add(new User("Kris","上海")); String json = mapper.writeValueAsString(al); System.out.print(json); 输出： [ {"name":"Tom","city":"沈阳"}, {"name":"Kris","city":"上海"} ]
json转对象 String json = "{"name":"Tom","city":"沈阳"}"; User user = mapper.readValue(json, User.class); System.out.println(user);
json转map<String,String>
HashMap<String,String> map = mapper.readValue(json, HashMap.class); System.out.println(map);
json转map<String,Object>
Map<String,User> map= mapper.readValue(json, HashMap.class); System.out.println(map);
json转list
ArrayList list= mapper.readValue(json, ArrayList.class); System.out.println(list);
json转list
List list= mapper.readValue(json, ArrayList.class); System.out.println(list);
