使用Google的Gson实现对象和json字符串之间的转换

http://penghuaiyi.iteye.com/blog/1922632

1.JsonUtil.java

Java代码


package com.snail.json;

import java.lang.reflect.Type;

import com.google.gson.Gson;

/**

* Java对象和JSON字符串相互转化工具类

* @author penghuaiyi

* @date 2013-08-10

*/

public final class JsonUtil {

private JsonUtil(){}

/**

* 对象转换成json字符串

* @param obj

* @return

*/

public static String toJson(Object obj) {

Gson gson = new Gson();

return gson.toJson(obj);

}

/**

* json字符串转成对象

* @param str

* @param type

* @return

*/

public static <T> T fromJson(String str, Type type) {

Gson gson = new Gson();

return gson.fromJson(str, type);

}

/**

* json字符串转成对象

* @param str

* @param type

* @return

*/

public static <T> T fromJson(String str, Class<T> type) {

Gson gson = new Gson();

return gson.fromJson(str, type);

}

}

2. Person.java

Java代码


package com.snail.json;

public class Person {

private int id;

private String name;

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;

}

}

3. Test.java

Java代码


package com.snail.json;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import com.google.gson.reflect.TypeToken;

public class Test {

/**

* 一般对象的转换

*/

public static void objectToJson(){

Person person = new Person();

person.setId(1);

person.setName("one");

//javabean转换成json字符串

String jsonStr = JsonUtil.toJson(person);

System.out.println(jsonStr);

//json字符串转换成javabean

Person newPerson = JsonUtil.fromJson(jsonStr, Person.class);

System.out.println(person == newPerson);

System.out.println(newPerson.getId()+","+newPerson.getName());

}

/**

* 复合结构数据转换(List)

*/

public static void listToJson(){

Person person1 = new Person();

person1.setId(1);

person1.setName("one");

Person person2 = new Person();

person2.setId(2);

person2.setName("two");

List<Person> list = new ArrayList<Person>();

list.add(person1);

list.add(person2);

//javabean转换成json字符串

String jsonStr = JsonUtil.toJson(list);

System.out.println(jsonStr);

//json字符串转换成javabean对象

List<Person> rtn = JsonUtil.fromJson(jsonStr, new TypeToken<List<Person>>(){}.getType());

for(Person person : rtn){

System.out.println(person.getId()+","+person.getName());

}

}

/**

* 复合结构数据转换(Map)

*/

public static void mapToJson(){

Person person1 = new Person();

person1.setId(1);

person1.setName("one");

Person person2 = new Person();

person2.setId(2);

person2.setName("two");

Map<Integer,Person> map = new HashMap<Integer,Person>();

map.put(person1.getId(), person1);

map.put(person2.getId(), person2);

//javabean转换成json字符串

String jsonStr = JsonUtil.toJson(map);

System.out.println(jsonStr);

//json字符串转换成Map对象

Map<Integer,Person> rtn = JsonUtil.fromJson(jsonStr, new TypeToken<Map<Integer,Person>>(){}.getType());

for(Entry<Integer, Person> entry : rtn.entrySet()){

Integer key = entry.getKey();

Person newPerson = entry.getValue();

System.out.println("key:"+key+","+newPerson.getId()+","+newPerson.getName());

}

}

public static void main(String[] args) {

objectToJson();

System.out.println("****************************");

listToJson();

System.out.println("****************************");

mapToJson();

}

}