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將Java的List結(jié)構(gòu)通過(guò)GSON庫(kù)轉(zhuǎn)換為JSON的方法示例

更新時(shí)間：2016年06月22日 10:57:07 作者：李坤

GONS是Google在GitHub上開(kāi)源的Java類(lèi)庫(kù),提供各種Java對(duì)象和JSON格式對(duì)象之間的轉(zhuǎn)換功能,將Java的List結(jié)構(gòu)通過(guò)GSON庫(kù)轉(zhuǎn)換為JSON的方法示例

發(fā)現(xiàn)了google的gson，因?yàn)橹皩?duì)于protocolbuf有一些了解，帶著一些好奇心，我開(kāi)始使用了gson。
GitHub主頁(yè)：https://github.com/google/gson
經(jīng)過(guò)比較，gson和其他現(xiàn)有java json類(lèi)庫(kù)最大的不同時(shí)gson需要序列化得實(shí)體類(lèi)不需要使用annotation來(lái)標(biāo)識(shí)需要序列化得字段，同時(shí)gson又可以通過(guò)使用annotation來(lái)靈活配置需要序列化的字段。
將List或者M(jìn)ap轉(zhuǎn)換成json非常簡(jiǎn)單：

public String getJsonData(List<?> list) {
  Gson gson = new Gson();
  String jsonstring = gson.toJson(list);
  return jsonstring;
}

下面我們會(huì)有詳細(xì)的例子。

示例
簡(jiǎn)單對(duì)象轉(zhuǎn)化和帶泛型的List轉(zhuǎn)化：

實(shí)體類(lèi):

public class Student { 
  private int id; 
  private String name; 
  private Date birthDay; 
 
  public int getId() { 
    return id; 
  } 
 
  public void setId(int id) { 
    this.id = id; 
  } 
 
  public String getName() { 
    return name; 
  } 
 
  public void setName(String name) { 
    this.name = name; 
  } 
 
  public Date getBirthDay() { 
    return birthDay; 
  } 
 
  public void setBirthDay(Date birthDay) { 
    this.birthDay = birthDay; 
  } 
 
  @Override 
  public String toString() { 
    return "Student [birthDay=" + birthDay + ", id=" + id + ", name=" 
        + name + "]"; 
  } 
 
}

測(cè)試類(lèi):

import java.util.ArrayList; 
import java.util.Date; 
import java.util.List; 
 
import com.google.gson.Gson; 
import com.google.gson.reflect.TypeToken; 
 
public class GsonTest1 { 
 
  public static void main(String[] args) { 
    Gson gson = new Gson(); 
 
    Student student1 = new Student(); 
    student1.setId(1); 
    student1.setName("李坤"); 
    student1.setBirthDay(new Date()); 
 
    // ////////////////////////////////////////////////////////// 
    System.out.println("----------簡(jiǎn)單對(duì)象之間的轉(zhuǎn)化-------------"); 
    // 簡(jiǎn)單的bean轉(zhuǎn)為json 
    String s1 = gson.toJson(student1); 
    System.out.println("簡(jiǎn)單Bean轉(zhuǎn)化為Json===" + s1); 
 
    // json轉(zhuǎn)為簡(jiǎn)單Bean 
    Student student = gson.fromJson(s1, Student.class); 
    System.out.println("Json轉(zhuǎn)為簡(jiǎn)單Bean===" + student); 
    // 結(jié)果: 
    // 簡(jiǎn)單Bean轉(zhuǎn)化為Json==={"id":1,"name":"李坤","birthDay":"Jun 22, 2012 8:27:52 AM"} 
    // Json轉(zhuǎn)為簡(jiǎn)單Bean===Student [birthDay=Fri Jun 22 08:27:52 CST 2012, id=1, 
    // name=李坤] 
    // ////////////////////////////////////////////////////////// 
 
    Student student2 = new Student(); 
    student2.setId(2); 
    student2.setName("曹貴生"); 
    student2.setBirthDay(new Date()); 
 
    Student student3 = new Student(); 
    student3.setId(3); 
    student3.setName("柳波"); 
    student3.setBirthDay(new Date()); 
 
    List<Student> list = new ArrayList<Student>(); 
    list.add(student1); 
    list.add(student2); 
    list.add(student3); 
 
    System.out.println("----------帶泛型的List之間的轉(zhuǎn)化-------------"); 
    // 帶泛型的list轉(zhuǎn)化為json 
    String s2 = gson.toJson(list); 
    System.out.println("帶泛型的list轉(zhuǎn)化為json==" + s2); 
 
    // json轉(zhuǎn)為帶泛型的list 
    List<Student> retList = gson.fromJson(s2, 
        new TypeToken<List<Student>>() { 
        }.getType()); 
    for (Student stu : retList) { 
      System.out.println(stu); 
    } 
 
    // 結(jié)果: 
    // 帶泛型的list轉(zhuǎn)化為json==[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 8:28:52 AM"},{"id":2,"name":"曹貴生","birthDay":"Jun 22, 2012 8:28:52 AM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 8:28:52 AM"}] 
    // Student [birthDay=Fri Jun 22 08:28:52 CST 2012, id=1, name=李坤] 
    // Student [birthDay=Fri Jun 22 08:28:52 CST 2012, id=2, name=曹貴生] 
    // Student [birthDay=Fri Jun 22 08:28:52 CST 2012, id=3, name=柳波] 
 
  } 
}

執(zhí)行結(jié)果:

----------簡(jiǎn)單對(duì)象之間的轉(zhuǎn)化------------- 
簡(jiǎn)單Bean轉(zhuǎn)化為Json==={"id":1,"name":"李坤","birthDay":"Jun 22, 2012 9:10:31 PM"} 
Json轉(zhuǎn)為簡(jiǎn)單Bean===Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=1, name=李坤] 
----------帶泛型的List之間的轉(zhuǎn)化------------- 
帶泛型的list轉(zhuǎn)化為json==[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 9:10:31 PM"},{"id":2,"name":"曹貴生","birthDay":"Jun 22, 2012 9:10:31 PM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 9:10:31 PM"}] 
Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=1, name=李坤] 
Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=2, name=曹貴生] 
Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=3, name=柳波]

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