fastjson 简单使用 及其JSONObject使用

阿里巴巴FastJson是一个Json处理工具包，包括“序列化”和“反序列化”两部分，它具备如下特征：
速度最快，测试表明，fastjson具有极快的性能，超越任其他的Java Json parser。包括自称最快的JackJson；
功能强大，完全支持Java Bean、集合、Map、日期、Enum，支持范型，支持自省；无依赖，能够直接运行在Java SE 5.0以上版本；支持Android；开源 (Apache 2.0)

源码地址：https://github.com/alibaba/fastjson

Fastjson API入口类是com.alibaba.fastjson.JSON，常用的序列化操作都可以在JSON类上的静态方法直接完成。

public static final Object parse(String text); // 把JSON文本parse为JSONObject或者JSONArray
*public static final JSONObject parseObject(String text)； // 把JSON文本parse成JSONObject
*public static final T parseObject(String text, Class clazz); // 把JSON文本parse为JavaBean
*public static final JSONArray parseArray(String text); // 把JSON文本parse成JSONArray
*public static final List parseArray(String text, Class clazz); //把JSON文本parse成JavaBean集合
*public static final String toJSONString(Object object); // 将JavaBean序列化为JSON文本
public static final String toJSONString(Object object, boolean prettyFormat); // 将JavaBean序列化为带格式的JSON文本
public static final Object toJSON(Object javaObject); 将JavaBean转换为JSONObject或者JSONArray。

maven:

<!-- https://mvnrepository.com/artifact/net.sf.json-lib/json-lib -->
<dependency>
<groupId>net.sf.json-lib</groupId>
<artifactId>json-lib</artifactId>
<version>2.4</version>
<classifier>jdk15</classifier>
</dependency>
<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.31</version>
</dependency>

一般只用第二个fastjson就可以

demo:

import com.alibaba.fastjson.JSON;

import java.util.ArrayList;
import java.util.List;

public class fastjson {

public static void main(String[] args) {
Group group = new Group();
group.setId(0L);
group.setName("admin");

User guestUser = new User();
guestUser.setId(2L);
guestUser.setName("guest");

User rootUser = new User();
rootUser.setId(3L);
rootUser.setName("root");

group.getUsers().add(guestUser);
group.getUsers().add(rootUser);

String jsonString = JSON.toJSONString(group);
System.out.println(jsonString);
Group group2 = JSON.parseObject(jsonString, Group.class);
}
}

class User {
private Long id;
private String name;

public Long getId() { return id; }
public void setId(Long id) { this.id = id; }

public String getName() { return name; }
public void setName(String name) { this.name = name; }
}
class Group {
private Long id;
private String name;
private List<User> users = new ArrayList<User>();

public Long getId() { return id; }
public void setId(Long id) { this.id = id; }

public String getName() { return name; }
public void setName(String name) { this.name = name; }

public List<User> getUsers() { return users; }
public void setUsers(List<User> users) { this.users = users; }
}

output:

{"id":0,"name":"admin","users":[{"id":2,"name":"guest"},{"id":3,"name":"root"}]}

2.查看JSONObject的使用

这个JSONObject在很多包里面都存在这个类，这里说的是fastjson包里面的使用

package com.qhong.fastjson;

//import com.alibaba.fastjson.JSONObject;

//import net.sf.json.JSONObject;

import com.alibaba.fastjson.JSONObject;

import java.util.HashMap;
import java.util.Map;

public class OperatorJSON {
public static void main(String[] args) {
createJson();
createJsonByMap();
createJsonByJavaBean();
}

private static void createJson() {
JSONObject obj = new JSONObject();
obj.put("name", "John");
obj.put("sex", "male");
obj.put("age", 22);
obj.put("is_student", true);
obj.put("hobbies", new String[] {"hiking", "swimming"});
//调用toString()方法可直接将其内容打印出来
System.out.println(obj.toString());
}

private static void createJsonByMap() {
Map<String, Object> data = new HashMap<String, Object>();
data.put("name", "John");
data.put("sex", "male");
data.put("age", 22);
data.put("is_student", true);
data.put("hobbies", new String[] {"hiking", "swimming"});

JSONObject obj = new JSONObject(data);
System.out.println(obj.toString());
}

private static void createJsonByJavaBean() {
PersonInfo info = new PersonInfo();
info.setName("John");
info.setSex("male");
info.setAge(22);
info.setStudent(true);
info.setHobbies(new String[] {"hiking", "swimming"});

String text= JSONObject.toJSONString(info);
System.out.println(text);
//        JSONObject obj = JSONObject.toJSON(info);
//        System.out.println(obj);
}

}

class PersonInfo {

private String name;
private String sex;
private int age;
private boolean isStudent;
private String[] hobbies;

public void setName(String name) {
this.name = name;
}
public void setSex(String sex) {
this.sex = sex;
}
public void setAge(int age) {
this.age = age;
}
public void setStudent(boolean isStudent) {
this.isStudent = isStudent;
}
public void setHobbies(String[] hobbies) {
this.hobbies = hobbies;
}
//getter不能少
public String getName() {
return name;
}
public String getSex() {
return sex;
}
public int getAge() {
return age;
}
public boolean isStudent() {
return isStudent;
}
public String[] getHobbies() {
return hobbies;
}
}

output:

{"hobbies":["hiking","swimming"],"sex":"male","name":"John","is_student":true,"age":22}
{"hobbies":["hiking","swimming"],"sex":"male","name":"John","is_student":true,"age":22}
{"age":22,"hobbies":["hiking","swimming"],"name":"John","sex":"male","student":true}

Process finished with exit code 0

可以从注释的区域看出，这个是fastjson包里面的，如果切换到net.sf.json包里面，那么就会报错！

http://blog.csdn.net/glarystar/article/details/6654494