如何在 Java 9 的 JShell 中导入 Gson 库?\n


Java 9 推出了一款名为JShell的交互式REPL命令行工具。它允许我们执行 Java 代码段并获得直接的结果。我们可以导入可通过类路径从 JShell 会话访问的外部类。Gson 库是一个 Java 序列化/反序列化库,旨在将Java 对象转换为JSON 以及反之亦然。

在以下代码段中,我们可以在 JShell 中设定类路径

jshell> /env --class-path C:\Users\User\gson.jar
| Setting new options and restoring state.


一旦在 JShell 中导入了gson 库 ,就能够在列表中看到该库。

jshell> import com.google.gson.*

jshell> /import
| import java.io.*
| import java.math.*
| import java.net.*
| import java.nio.file.*
| import java.util.*
| import java.util.concurrent.*
| import java.util.function.*
| import java.util.prefs.*
| import java.util.regex.*
| import java.util.stream.*
| import com.google.gson.*

jshell> Gson g = new GsonBuilder().setPrettyPrinting().create()
g ==> {serializeNulls:false,factories:[Factory[typeHier ... 78b9],instanceCreators:{}}


在以下代码段中,我们创建了一个Employee 类。

jshell> class Employee {
...>       private String firstName;
...>       private String lastName;
...>       private String designation;
...>       private String location;
...>       public Employee(String firstName, String lastName, String desigation, String location) {
...>          this.firstName = firstName;
...>          this.lastName = lastName;
...>          this.designation = designation;
...>          this.location = location;
...>       }
...>       public String getFirstName() {
...>          return firstName;
...>       }
...>       public String getLastName() {
...>          return lastName;
...>       }
...>       public String getJobDesignation() {
...>          return designation;
...>       }
...>       public String getLocation() {
...>          return location;
...>       }
...>       public String toString() {
...>          return "Name = " + firstName + ", " + lastName + " | " +
...>                 "Job designation = " + designation + " | " +
...>                 "location = " + location + ".";
...>       }
...>    }
| created class Employee

jshell> Employee e = new Employee("Jai", "Adithya", "Content Developer", "Hyderabad");
e ==> Name = Jai, Adithya | Job designation = Content D ... er | location = Hyderabad.

jshell> String empSerialized = g.toJson(e)
empSerialized ==> "{\n \"firstName\": \"Jai\",\n \"lastName\": \" ... ation\": \"Hyderabad\"\n}"


在以下代码段中,我们可以创建Employee 对象的实例并显示结果。

jshell> System.out.println(empSerialized)
{
   "firstName": "Jai",
   "lastName": "Adithya",
   "designation": "Content Developer",
   "location": "Hyderabad"
}
jshell> Employee e1 = g.fromJson(empSerialized, Employee.class)
e1 ==> Name = Jai, Adithya | Job designation = Content D ... er | location = Hyderabad.

更新于: 2020-04-02

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