1.fastjson.jar包的导入

贴上fastjson在GitHub上的地址fastjson

2.同时下载fastjson的源码

将源码导入IDE中

3.开始测试

3.1抽象类JSON的介绍

JSON类是使用fastjson的主要类，通常调用
该类的两个静态方法toJSONString(Object)和parseObject(String,Class)。toJSONString（Object）方法实现将Java对象转换为JSON字符串，parseObject(String,Class）方法将字符串解析为Class指定的Java对象,如果缺省Class参数，则把String解析为JSONObject类型的对象。

public class fastJsonTest {
    public static void main(String[] args) {
        Student student = new Student("王五",28,"10003");
        Object o = JSON.toJSON(student);
        System.out.println(o.getClass());
        String s = JSON.toJSONString(student);
        System.out.println(s);
        System.out.println("=====================");
        String stu = "{\"age\":28,\"classNum\":\"10003\",\"name\":\"王五\"}";
        Object stuO = JSON.parseObject(stu,Student.class);
        System.out.println(stuO.getClass());
        Object o1 = JSON.parse(stu);
        System.out.println(o1.getClass());
    }

运行结果如下：

class com.alibaba.fastjson.JSONObject
{"age":28,"classNum":"10003","name":"王五"}
=====================
class lgp.learn.string010301.Student
class com.alibaba.fastjson.JSONObject

3.2 ParameterizedType

parameterizedType 是位于java.lang.reflect包中的接口，Type接口的子接口，API中是这样解释的“ParameterizedType 表示参数化类型，例如 Collection<String>”。
如果你正在序列化/反序列化的对象是ParameterizedType类型的，即参数化类型的对象，需要使用JSON类的toJSONStirng(Object)方法和parseObject(String,Type,Feature[])方法，测试代码如下：

 String s = "[{\"age\":23,\"classNum\":\"10001\",\"name\":\"张三\"}," +
                "{\"age\":24,\"classNum\":\"10002\",\"name\":\"李四\"}," +
                "{\"age\":25,\"classNum\":\"10003\",\"name\":\"王五\"}]";
        System.out.println("将字符串s解析为Student类型的列表方法1：");
        Type listType = new TypeReference<List<Student>>(){}.getType();
        List<Student> list = JSON.parseObject(s,listType);
        for(Student stu:list) System.out.println(stu);

        System.out.println("==================");
        System.out.println("将字符串s解析为Student类型的列表方法2：");
        JSONArray ja = JSONArray.parseArray(s);
        for(Object o:ja){
            JSONObject jo = (JSONObject) o;
            System.out.print(jo.getClass());
            System.out.print(":"+jo);
            System.out.println();
            Student stu = JSON.parseObject(o.toString(),Student.class);
            System.out.print(stu.getClass());
            System.out.print(":"+stu);
            System.out.println();
        }
        System.out.println("==================");
        System.out.println("将Student类型的列表解析为字符串：");
        ArrayList<Student> stus = new ArrayList<>();
        stus.add(new Student("张三",23,"10001"));
        stus.add(new Student("李四",24,"10002"));
        stus.add(new Student("王五",25,"10003"));
        String students = JSON.toJSONString(stus);
        System.out.println(students);

运行结果

将字符串s解析为Student类型的列表方法1：
Student{name='张三', age=23, classNum='10001'}
Student{name='李四', age=24, classNum='10002'}
Student{name='王五', age=25, classNum='10003'}
==================
将字符串s解析为Student类型的列表方法2：
class com.alibaba.fastjson.JSONObject:{"name":"张三","classNum":"10001","age":23}
class lgp.learn.string010301.Student:Student{name='张三', age=23, classNum='10001'}
class com.alibaba.fastjson.JSONObject:{"name":"李四","classNum":"10002","age":24}
class lgp.learn.string010301.Student:Student{name='李四', age=24, classNum='10002'}
class com.alibaba.fastjson.JSONObject:{"name":"王五","classNum":"10003","age":25}
class lgp.learn.string010301.Student:Student{name='王五', age=25, classNum='10003'}
==================
将Student类型的列表解析为字符串：
[{"age":23,"classNum":"10001","name":"张三"},{"age":24,"classNum":"10002","name":"李四"},{"age":25,"classNum":"10003","name":"王五"}]