Jackson学习笔记-对象序列化

一、用ObjectMapper.readValue(jsonString, Student.class) , ObjectMapper.writeValueAsString(student)

import java.io.IOException;

import org.codehaus.jackson.JsonParseException;

import org.codehaus.jackson.map.JsonMappingException;

import org.codehaus.jackson.map.ObjectMapper;

import org.codehaus.jackson.map.SerializationConfig;



public class JacksonTester {

   public static void main(String args[]){

	   

	  //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}";



      //map json to student

      try {

         Student student = mapper.readValue(jsonString, Student.class);

         System.out.println(student);

         

         mapper.enable(SerializationConfig.Feature.INDENT_OUTPUT);

         jsonString = mapper.writeValueAsString(student);

         System.out.println(jsonString);



      } catch (JsonParseException e) {

         e.printStackTrace();

      } catch (JsonMappingException e) {

         e.printStackTrace();

      } catch (IOException e) {

         e.printStackTrace();

      }

   }

}



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+ " ]";

   }	

}

　　

 

二、将Java对象序列化到一个JSON文件，然后再读取JSON文件获取转换为对象。在这个例子中，创建了Student类。创建将有学生对象以JSON表示在一个student.json文件。

import java.io.File;

import java.io.IOException;



import org.codehaus.jackson.JsonGenerationException;

import org.codehaus.jackson.JsonParseException;

import org.codehaus.jackson.map.JsonMappingException;

import org.codehaus.jackson.map.ObjectMapper;





public class JacksonTester2 {

   public static void main(String args[]){

      JacksonTester2 tester = new JacksonTester2();

      try {

         Student student = new Student();

         student.setAge(10);

         student.setName("Mahesh");

         tester.writeJSON(student);



         Student student1 = tester.readJSON();

         System.out.println(student1);



      } catch (JsonParseException e) {

         e.printStackTrace();

      } catch (JsonMappingException e) {

         e.printStackTrace();

      } catch (IOException e) {

         e.printStackTrace();

      }

   }



   

   //这里将介绍将Java对象序列化到一个JSON文件，然后再读取JSON文件获取转换为对象。

   //在这个例子中，创建了Student类。创建将有学生对象以JSON表示在一个student.json文件。

   private void writeJSON(Student student) throws JsonGenerationException, JsonMappingException, IOException{

      ObjectMapper mapper = new ObjectMapper();	

      mapper.writeValue(new File("student.json"), student);

   }



   private Student readJSON() throws JsonParseException, JsonMappingException, IOException{

      ObjectMapper mapper = new ObjectMapper();

      Student student = mapper.readValue(new File("student.json"), Student.class);

      return student;

   }

}