Jackson - 完整数据绑定

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  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 ]