Jackson 简明教程

Jackson - Object Serialization

现在我们将某个 java 对象序列化为 json 文件，然后阅读该 json 文件以获取该对象。在这个示例中，我们创建了 Student 类。我们将创建一个 student.json 文件，其中将有 Student 对象的 json 表示。

在 C:>Jackson_WORKSPACE 中创建一个名为 JacksonTester 的 java 类文件。

文件：JacksonTester.java

import java.io.File;
import java.io.IOException;

import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonTester {
   public static void main(String args[]){
      JacksonTester tester = new JacksonTester();
      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();
      }
   }

   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;
   }
}

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+ " ]";
   }
}

Verify the result

使用 javac 编译器编译类，如下所示：

C:\Jackson_WORKSPACE>javac JacksonTester.java

现在运行 jacksonTester 查看结果：

C:\Jackson_WORKSPACE>java JacksonTester

验证输出

Student [ name: Mahesh, age: 10 ]