Gson從序列化中排除字段

默認情況下，GSON排除序列化/反序列化過程中的瞬態和靜態字段。 我們來看看下麵的例子。

示例

創建一個名為GsonTester的Java類檔:GsonTester.java -

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

public class GsonTester {
   public static void main(String args[]) {
      GsonBuilder builder = new GsonBuilder();
      Gson gson = builder.create();

      Student student = new Student();
      student.setRollNo(1);
      student.setName("Maxsu");
      student.setVerified(true);
      student.setId(1);
      student.className = "VI";

      String jsonString = gson.toJson(student);
      System.out.println(jsonString);
   }
}
class Student {
   private int rollNo;
   private String name;
   private boolean verified;
   private transient int id;
   public static String className;

   public int getRollNo() {
      return rollNo;
   }
   public void setRollNo(int rollNo) {
      this.rollNo = rollNo;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public void setVerified(boolean verified) {
      this.verified = verified;
   }
   public boolean isVerified() {
      return verified;
   }
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
}

執行上面示例代碼，得到以下結果 -

{"rollNo":1,"name":"Maxsu","verified":true}

使用excludeFieldsWithModifiers()方法

GsonBuilder使用序列化/反序列化過程中的excludeFieldsWithModifiers()方法提供對使用特定修飾符排除字段的控制。 看下麵的例子。

示例

創建一個名為GsonTester的Java類檔:GsonTester.java -

import java.lang.reflect.Modifier;

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

public class GsonTester {
   public static void main(String args[]) {
      GsonBuilder builder = new GsonBuilder();
      builder.excludeFieldsWithModifiers(Modifier.TRANSIENT);
      Gson gson = builder.create();

      Student student = new Student();
      student.setRollNo(1);
      student.setName("Maxsu");
      student.setVerified(true);
      student.setId(1);
      student.className = "VI";

      String jsonString = gson.toJson(student);
      System.out.println(jsonString);
   }
}
class Student {
   private int rollNo;
   private String name;
   private boolean verified;
   private transient int id;
   public static String className;

   public int getRollNo() {
      return rollNo;
   }
   public void setRollNo(int rollNo) {
      this.rollNo = rollNo;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public void setVerified(boolean verified) {
      this.verified = verified;
   }
   public boolean isVerified() {
      return verified;
   }
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
}

執行上面示例代碼，得到以下結果 -

{"rollNo":1,"name":"Maxsu","verified":true,"className":"VI"}

使用@Expose注解

Gson提供@Expose注解來根據其範圍控制類的Json序列化/反序列化。 考慮以下具有@Expose支持的變數的類。 在這個類中，name和rollno變數將被暴露以進行序列化。 然後，我們使用GsonBuilder.excludeFieldsWithoutExposeAnnotation()方法來指示只有暴露的變數要被序列化/反序列化。 看下麵的例子。

示例

創建一個名為GsonTester的Java類檔:GsonTester.java -

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

public class GsonTester {
   public static void main(String args[]) {
      GsonBuilder builder = new GsonBuilder();
      builder.excludeFieldsWithoutExposeAnnotation();
      Gson gson = builder.create();

      Student student = new Student();
      student.setRollNo(1);
      student.setName("Maxsu");
      student.setVerified(true);
      student.setId(1);
      student.className = "VI";

      String jsonString = gson.toJson(student);
      System.out.println(jsonString);
   }
}
class Student {
   @Expose
   private int rollNo;

   @Expose
   private String name;
   private boolean verified;
   private int id;
   public static String className;

   public int getRollNo() {
      return rollNo;
   }
   public void setRollNo(int rollNo) {
      this.rollNo = rollNo;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public void setVerified(boolean verified) {
      this.verified = verified;
   }
   public boolean isVerified() {
      return verified;
   }
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
}

執行上面示例代碼，得到以下結果 -

{"rollNo":1,"name":"Maxsu"}