Jackson - 完整数据绑定

简述

完整数据绑定是指将 JSON 映射到任何 JAVA 对象。


//Create an ObjectMapper instance
ObjectMapper mapper = new ObjectMapper();   
//map JSON content to Student object
Student student = mapper.readValue(new File("student.json"), Student.class);
//map Student object to JSON content
mapper.writeValue(new File("student.json"), student);

让我们看看简单的数据绑定的实际应用。在这里，我们将 JAVA 对象直接映射到 JSON，反之亦然。

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+ " ]";
   }    
}

验证结果

使用 javac 编译器编译类，如下所示：


C:\Jackson_WORKSPACE>javac JacksonTester.java

现在运行 JacksonTester 以查看结果：


C:\Jackson_WORKSPACE>java JacksonTester

验证输出


Student [ name: Mahesh, age: 10 ]