public static void main(String args[]) throws JsonParseException, JsonMappingException, IOException {// 第1步：创建ObjectMapper对象。// 创建ObjectMapper对象。它是一个可重复使用的对象。ObjectMapper mapper = new ObjectMapper();String jsonString = "{\"name\":\"Mahesh\", \"age\":21}";// 第2步：反序列化JSON到对象。// 从JSON对象使用readValue()方法来获取。通过JSON字符串和对象类型作为参数JSON字符串/来源。//map json to studentStudent student = mapper.readValue(jsonString, Student.class);System.out.println(student);// 第3步：序列化对象到JSON。// 使用writeValueAsString()方法来获取对象的JSON字符串表示。jsonString = mapper.writeValueAsString(student);System.out.println(jsonString);}

public class Student {private String name;private int age;public Student() {}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String toString() {return "Student [ name: " + name + ", age: " + age + " ]";}
}

public static void main(String args[]) throws JsonGenerationException, JsonMappingException, IOException {ObjectMapper mapper = new ObjectMapper();Map<String, Object> studentDataMap = new HashMap<String, Object>();int[] marks = { 1, 2, 3 };Student student = new Student();student.setAge(10);student.setName("Mahesh");// JAVA ObjectstudentDataMap.put("student", student);// JAVA StringstudentDataMap.put("name", "Mahesh Kumar");// JAVA BooleanstudentDataMap.put("verified", Boolean.FALSE);// ArraystudentDataMap.put("marks", marks);mapper.writeValue(new File("student3.json"), studentDataMap);//result student.json//{ //   "student":{"name":"Mahesh","age":10},//   "marks":[1,2,3],//   "verified":false,//   "name":"Mahesh Kumar"//}studentDataMap = mapper.readValue(new File("student3.json"), Map.class);System.out.println(studentDataMap.get("student"));System.out.println(studentDataMap.get("name"));System.out.println(studentDataMap.get("verified"));System.out.println(studentDataMap.get("marks"));}

        // 第2步：反序列化JSON到对象。// 从JSON对象使用readValue()方法来获取。通过JSON字符串和对象类型作为参数JSON字符串/来源。//map json to studentStudent student = mapper.readValue(jsonString, Student.class);System.out.println(student);

public static void main(String args[]) throws JsonProcessingException, IOException {ObjectMapper mapper = new ObjectMapper();String jsonString = "{\"name\":\"Mahesh Kumar\", \"age\":21,\"verified\":false,\"marks\": [100,90,85]}";// 从JSON创建树JsonNode rootNode = mapper.readTree(jsonString);// 使用相对路径来根节点在遍历树，并处理该数据得到的每个节点。考虑下面的代码片段遍历提供的根节点的树。JsonNode nameNode = rootNode.path("name");System.out.println("Name: " + nameNode.textValue());JsonNode ageNode = rootNode.path("age");System.out.println("Age: " + ageNode.intValue());JsonNode verifiedNode = rootNode.path("verified");System.out.println("Verified: " + (verifiedNode.booleanValue() ? "Yes" : "No"));JsonNode marksNode = rootNode.path("marks");Iterator<JsonNode> iterator = marksNode.elements();System.out.print("Marks: [ ");while (iterator.hasNext()) {JsonNode marks = iterator.next();System.out.print(marks.intValue() + " ");}System.out.println("]");}

    public static void main(String args[]) throws JsonGenerationException, JsonMappingException, IOException {ObjectMapper mapper = new ObjectMapper();String jsonString = "{\"name\":\"Mahesh\", \"age\":21}";// 从JSON创建树JsonNode rootNode = mapper.readTree(jsonString);Student student = mapper.treeToValue(rootNode, Student.class);System.out.println(student);}

JsonFactory jasonFactory = new JsonFactory();
JsonGenerator jsonGenerator = jasonFactory.createJsonGenerator(new File("student.json"), JsonEncoding.UTF8);
jsonGenerator.writeStartObject();
// "name" : "Mahesh Kumar"
jsonGenerator.writeStringField("name", "Mahesh Kumar");

JsonFactory jasonFactory = new JsonFactory();
JJsonParser jsonParser = jasonFactory.createJsonParser(new File("student.json"));
while (jsonParser.nextToken() != JsonToken.END_OBJECT) {//get the current tokenString fieldname = jsonParser.getCurrentName();if ("name".equals(fieldname)) {//move to next token
      jsonParser.nextToken();System.out.println(jsonParser.getText());             }
}

  ObjectMapper mapper = new ObjectMapper();List<Budget> budgets = mapper.readValue(jsonString, new TypeReference<List<Budget>>() { });

package com.xc.json.JackSon;import java.util.Iterator;
import java.util.List;
import java.util.Map;import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;public class JackSon {public static void main(String[] args) throws Exception {String json = "{\"username\":\"zhangsan\",\"性别\":\"男\",\"company\":{\"companyName\":\"中华\",\"address\":\"北京\"},\"cars\":[\"蔚蓝\",\"特斯拉\"],\"logList\":[{\"id\":123,\"name\":\"abc\"},{\"id\":234,\"name\":\"efff\"}]}";System.out.println(json);ObjectMapper mapper = new ObjectMapper();JsonNode rootNode = mapper.readTree(json);// String的处理JsonNode usernameNode = rootNode.path("username");System.out.println("==username==");String textValue = usernameNode.textValue();System.out.println("textValue:" + textValue);String asText = usernameNode.asText();System.out.println("asText:" + asText);String username = mapper.writeValueAsString(usernameNode);System.out.println("username:" + username);// 转换成类型,Map类型，同样Integer,String,List，也可以同样处理JsonNode companyNode = rootNode.path("company");String company = mapper.writeValueAsString(companyNode);Map<String, Object> companyMap = mapper.readValue(company, Map.class);System.out.println("==company==");System.out.println(companyMap);// 数组的处理JsonNode carsNode = rootNode.path("cars");System.out.println("==cars==");Iterator<JsonNode> iterator = carsNode.elements();System.out.print("cars: [ ");while (iterator.hasNext()) {JsonNode marks = iterator.next();System.out.print(marks.textValue() + " ");}System.out.println("]");// 转换成List<Log>，类型JsonNode logListNode = rootNode.path("logList");String logJson = mapper.writeValueAsString(logListNode);JavaType logType = mapper.getTypeFactory().constructParametricType(List.class, Log.class);List<Log> logList = mapper.readValue(logJson, logType);System.out.println("==logList==");System.out.println(logList);}
}

package com.xc.json.JackSon;class Log {private int id;private String name;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}@Overridepublic String toString() {return "log [id=" + id + ", name=" + name + "]";}}