Java(자바) jackson(잭슨) JSON(제이슨)

15년 7월 기준.

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<dependency>

<groupId>org.codehaus.jackson</groupId>

<artifactId>jackson-mapper-asl</artifactId>

<version>1.9.13</version>

</dependency>

​

ObjectMapper mapper = new ObjectMapper();

String json = "{\"name\":\"james\", \"age\":24, \"messages\" : [\"msg 1\",\"msg 2\",\"msg 3\"] }";

Map<String, Object> map = new HashMap<String, Object>();

map = mapper.readValue(json, new TypeReference<Map<String, String>>(){});

System.out.println(map);

System.out.println(map.get("name"));

ArrayList arr = (ArrayList)map.get("messages");

System.out.println(arr.get(2));

// json to map

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ObjectMapper mapper = new ObjectMapper();

String json = "";

Map<String, Object> map = new HashMap<String, Object>();

map.put("name", "james");

map.put("age", 24);

List<Object> list = new ArrayList<Object>();

list.add("msg 1");

list.add("msg 2");

list.add("msg 3");

// json = mapper.writeValueAsString(map);

json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(map);

System.out.println(json);

// map to json

​

Map<String, Object> map = mapper.readValue(new File("c:\\test\\user.json"), new TypeReference<Map<String, Object>>() {});

mapper.writeValue(new File("c:\\test\\user.json"), map);

// json i/o