Java to JSON：
1 package json.jackson; 2 3 import bean.User; 4 import com.fasterxml.jackson.databind.ObjectMapper; 5 6 import java.io.File; 7 import java.util.Map; 8 9 /**10 * Jackson – Java to JSON11 * 功能：JSON与Java对象、Map等类型转换，JSON文件的读写等12 * 依赖包：jackson-databind-2.8.11.1.jar、jackson-core-2.8.10.jar、jackson-annotations-2.8.0.jar13 * https://github.com/FasterXML/jackson-databind14 */15 public class JavaToJSON {16 public static void main(String[] ars) throws Exception {17 User user = new User("tom", 25, "NO.1 street");18 ObjectMapper objectMapper = new ObjectMapper();19 20 // Java对象转json，也支持bytes21 String json = objectMapper.writeValueAsString(user);22 System.out.println("Java对象转json:" + json);23 24 // json转Java对象25 User user2 = objectMapper.readValue(json, User.class);26 System.out.println("json转Java对象" + user2);27 28 // 读文件29 String jsonFilePath = "src/main/java/json/jackson/JsonReader.json";30 User user3 = objectMapper.readValue(new File(jsonFilePath), User.class);31 System.out.println("读取JSON文件：" + user3);32 // 写文件33 objectMapper.writeValue(new File(jsonFilePath), user3);34 35 // json转map，也支持List36 Map map = objectMapper.readValue(json, Map.class);37 System.out.println("json转map：" + map);38 39 // map转json字符串，支持所有类型转字符串40 String json2 = objectMapper.writeValueAsString(map);41 System.out.println("map转json:" + json2);42 43 }44 } JsonNode：
1 package json.jackson; 2 3 import com.fasterxml.jackson.databind.JsonNode; 4 import com.fasterxml.jackson.databind.ObjectMapper; 5 6 import java.io.File; 7 import java.util.List; 8 9 /**10 * JsonNode11 * 处理复杂的JSON，返回多个对象的情况12 * 从文件中读取复杂的JSON，根据key找到对应value值13 * 依赖包：jackson-databind-2.8.11.1.jar、jackson-core-2.8.10.jar、jackson-annotations-2.8.0.jar14 * https://github.com/FasterXML/jackson-databind15 */16 public class JSONTreeDemo {17 public static void main(String[] ars) throws Exception {18 ObjectMapper objectMapper = new ObjectMapper();19 String jsonFilePath = "src/main/java/json/jackson/Json2.json";20 // 以树形态支持多对象的情况：支持读取多种类型21 JsonNode jsonNode = objectMapper.readTree(new File(jsonFilePath));22 System.out.println("jsonNode：" + jsonNode);23 // 根据key查询多个值，返回list24 List list = jsonNode.findValues("name");25 System.out.println("Values：" + list);26 27 // 根据key查询单个值28 String channel = jsonNode.get("channel").asText();29 System.out.println("查询channel的值：" + channel);30 }31 }