Gson 简明教程

Gson - Object Serialization

让我们将 Java 对象序列化到 Json 文件,然后读取该 Json 文件以返回该对象。在此示例中,我们创建了 Student 类。我们将创建一个 student.json 文件,该文件将有一个 jsonStudent 对象表示形式。

Example

C:>GSON_WORKSPACE 中创建名为 GsonTester 的 Java 类文件。

File - GsonTester.java

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class GsonTester {
   public static void main(String args[]) {

      GsonTester tester = new GsonTester();
      try {
         Student student = new Student();
         student.setAge(10);
         student.setName("Mahesh");
         tester.writeJSON(student);
         Student student1 = tester.readJSON();
         System.out.println(student1);
      }
      catch(FileNotFoundException e) {
         e.printStackTrace();
      }
      catch(IOException e) {
         e.printStackTrace();
      }
   }

   private void writeJSON(Student student) throws IOException {
      GsonBuilder builder = new GsonBuilder();
      Gson gson = builder.create();
      FileWriter writer = new FileWriter("student.json");
      writer.write(gson.toJson(student));
      writer.close();
   }

   private Student readJSON() throws FileNotFoundException {
      GsonBuilder builder = new GsonBuilder();
      Gson gson = builder.create();
      BufferedReader bufferedReader = new BufferedReader(
         new FileReader("student.json"));

      Student student = gson.fromJson(bufferedReader, 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

使用以下 javac 编译器编译类:

C:\GSON_WORKSPACE>javac GsonTester.java

现在运行 GsonTester 来查看结果 −

C:\GSON_WORKSPACE>java GsonTester

验证输出

Student [ name: Mahesh, age: 10 ]