Gson 简明教程
Gson - Excluding fields from Serialization
默认情况下,GSON 会将瞬态和静态字段排除在序列化/反序列化过程中。让我们来看一下下面的示例。
Example
在 C:\>GSON_WORKSPACE 创建一个名为 GsonTester 的 Java 类文件。
File − 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("Mahesh Kumar");
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;
}
}
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 以查看结果 −
C:\GSON_WORKSPACE>java GsonTester
验证输出
{"rollNo":1,"name":"Mahesh Kumar","verified":true}
Using excludeFieldsWithModifiers
GsonBuilder 提供对使用 excludeFieldsWithModifiers() 方法排除具有特殊修饰符的字段的控制,以排除序列化/反序列化过程。请参阅以下示例。
Example
在 C:\>GSON_WORKSPACE 中创建一个名为 GsonTester 的 Java 类文件。
File − 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("Mahesh Kumar");
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;
}
}
Using @Expose Annotation
Gson 提供 @Expose 注释来控制基于类的作用域的 Json 序列化/反序列化。考虑具有变量具有 @Expose 支持的以下类。此类中, name 和 rollno 变量公开序列化。然后,我们使用 GsonBuilder.excludeFieldsWithoutExposeAnnotation() 方法来指示仅公开变量将被序列化/反序列化。请参阅以下示例。
Example
在 C:\>GSON_WORKSPACE 创建一个名为 GsonTester 的 Java 类文件。
File − 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("Mahesh Kumar");
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;
}
}