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