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;
}
}