FastJson 基础教程

介绍

Fastjson是一个Java语言编写的高性能功能完善的JSON库。它采用一种“假定有序快速匹配”的算法，把JSON Parse的性能提升到极致，是目前Java语言中最快的JSON库。Fastjson接口简单易用，已经被广泛使用在缓存序列化、协议交互、Web输出、Android客户端等多种应用场景。

教程

maven依赖

<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.24</version>
</dependency>

package com.zzg.entity;

import java.io.Serializable;

public class Address implements Serializable {

/**
* 
*/
private static final long serialVersionUID = 1L;

private int id;
private String provice;
private String city;
private String area;

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getProvice() {
return provice;
}

public void setProvice(String provice) {
this.provice = provice;
}

public String getCity() {
return city;
}

public void setCity(String city) {
this.city = city;
}

public String getArea() {
return area;
}

public void setArea(String area) {
this.area = area;
}

}

package com.zzg.entity;

import java.io.Serializable;

import java.util.List;

public class User implements Serializable {

/**
* 
*/
private static final long serialVersionUID = 1L;

private int id;
private String name;
private int sex;
private List<Address> list;

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 int getSex() {
return sex;
}

public void setSex(int sex) {
this.sex = sex;
}

public List<Address> getList() {
return list;
}

public void setList(List<Address> list) {
this.list = list;
}

}

1、序列化

主要通过 JSON.toJSONString方法将Bean转换为json。

//通过 JSON.toJSONString方法将Bean转换为json。
User user =new User();
user.setId(1);
user.setName("周志刚");
user.setSex(1);

List<Address> address=new ArrayList<Address>();
Address one  = new Address();
one.setArea("开福区");
one.setCity("长沙市");
one.setId(1);
one.setProvice("湖南省");

address.add(one);

Address two  = new Address();
two.setArea("天河区");
two.setCity("广州市");
two.setId(1);
two.setProvice("广东省");

address.add(two);
user.setList(address);
System.out.println("结果："+JSON.toJSONString(user));

结果如下：

{"id":1,"list":[{"area":"开福区","city":"长沙市","id":1,"provice":"湖南省"},{"area":"天河区","city":"广州市","id":1,"provice":"广东省"}],"name":"周志刚","sex":1}

2、反序列化

主要通过JSON.parseObject方法将json转换为Bean对象，如下：

//通过JSON.parseObject方法将json转换为Bean对象

String json = "{\"id\":1,\"list\":[{\"area\":\"开福区\",\"city\":\"长沙市\",\"id\":1,\"provice\":\"湖南省\"},{\"area\":\"天河区\",\"city\":\"广州市\",\"id\":1,\"provice\":\"广东省\"}],\"name\":\"周志刚\",\"sex\":1}";
User u = JSON.parseObject(json, User.class);

System.out.println("用户名次:"+u.getName());

结果如下：

用户名次:周志刚

3、JSONField 介绍

package com.alibaba.fastjson.annotation;

public @interface JSONField {

    // 配置序列化和反序列化的顺序，1.1.42版本之后才支持

    int ordinal() default 0;

     // 指定字段的名称

    String name() default "";

    // 指定字段的格式，对日期格式有用

    String format() default "";

    // 是否序列化

    boolean serialize() default true;

    // 是否反序列化

    boolean deserialize() default true;

}

3.1 指定序列化名称

指定User的list属性在序列化时变成addr_list，如下：

package com.zzg.entity;

import java.io.Serializable;

import java.util.List;

import com.alibaba.fastjson.annotation.JSONField;

public class User implements Serializable {

/**
* 
*/
private static final long serialVersionUID = 1L;

private int id;
private String name;
private int sex;

@JSONField(name="addr_list")
private List<Address> list;

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 int getSex() {
return sex;
}

public void setSex(int sex) {
this.sex = sex;
}

public List<Address> getList() {
return list;
}

public void setList(List<Address> list) {
this.list = list;
}

}

输出结果：

{"addr_list":[{"area":"开福区","city":"长沙市","id":1,"provice":"湖南省"},{"area":"天河区","city":"广州市","id":1,"provice":"广东省"}],"id":1,"name":"周志刚","sex":1}

3.2 使用serialize/deserialize指定字段不序列化

控制sex属性不序列化，如下：

package com.zzg.entity;

import java.io.Serializable;

import java.util.List;

import com.alibaba.fastjson.annotation.JSONField;

public class User implements Serializable {

/**
* 
*/
private static final long serialVersionUID = 1L;

private int id;
private String name;
@JSONField(serialize=false)
private int sex;

@JSONField(name="addr_list")
private List<Address> list;

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 int getSex() {
return sex;
}

public void setSex(int sex) {
this.sex = sex;
}

public List<Address> getList() {
return list;
}

public void setList(List<Address> list) {
this.list = list;
}

}

结果输出：

{"addr_list":[{"area":"开福区","city":"长沙市","id":1,"provice":"湖南省"},{"area":"天河区","city":"广州市","id":1,"provice":"广东省"}],"id":1,"name":"周志刚"}

3.3 使用ordinal指定字段的顺序

package com.zzg.entity;

import java.io.Serializable;

import com.alibaba.fastjson.annotation.JSONField;

public class Address implements Serializable {

/**
* 
*/
private static final long serialVersionUID = 1L;
@JSONField(ordinal = 4)
private int id;
@JSONField(ordinal = 1)
private String provice;
@JSONField(ordinal = 2)
private String city;
@JSONField(ordinal = 3)
private String area;

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getProvice() {
return provice;
}

public void setProvice(String provice) {
this.provice = provice;
}

public String getCity() {
return city;
}

public void setCity(String city) {
this.city = city;
}

public String getArea() {
return area;
}

public void setArea(String area) {
this.area = area;
}

}

输出结果：

{"addr_list":[{"provice":"湖南省","city":"长沙市","area":"开福区","id":1},{"provice":"广东省","city":"广州市","area":"天河区","id":1}],"id":1,"name":"周志刚"}

参考资料： 
https://github.com/alibaba/fastjson/wiki/JSONField