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;
   }
}