com.alibaba的fastjson简介

fastjson简介

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

1.前言

1.1.FastJson的介绍:

JSON协议使用方便，越来越流行,JSON的处理器有很多,这里我介绍一下FastJson,FastJson是阿里的开源框架,被不少企业使用,是一个极其优秀的Json框架,Github地址: FastJson

1.2.FastJson的特点:

1.FastJson数度快,无论序列化和反序列化,都是当之无愧的fast 
2.功能强大(支持普通JDK类包括任意Java Bean Class、Collection、Map、Date或enum) 
3.零依赖(没有依赖其它任何类库)

1.3.FastJson的简单说明:

FastJson对于json格式字符串的解析主要用到了下面三个类： 
1.JSON：fastJson的解析器，用于JSON格式字符串与JSON对象及javaBean之间的转换 
2.JSONObject：fastJson提供的json对象 
3.JSONArray：fastJson提供json数组对象

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2.FastJson的用法

首先定义三个json格式的字符串

//json字符串-简单对象型
private static final String  JSON_OBJ_STR = "{\"studentName\":\"lily\",\"studentAge\":12}";

//json字符串-数组类型
private static final String  JSON_ARRAY_STR = "[{\"studentName\":\"lily\",\"studentAge\":12},{\"studentName\":\"lucy\",\"studentAge\":15}]";

//复杂格式json字符串
private static final String  COMPLEX_JSON_STR = "{\"teacherName\":\"crystall\",\"teacherAge\":27,\"course\":{\"courseName\":\"english\",\"code\":1270},\"students\":[{\"studentName\":\"lily\",\"studentAge\":12},{\"studentName\":\"lucy\",\"studentAge\":15}]}";

2.1.JSON格式字符串与JSON对象之间的转换

2.1.1.json字符串-简单对象型与JSONObject之间的转换

/**
 * json字符串-简单对象型到JSONObject的转换
 */
@Test
public void testJSONStrToJSONObject() {

    JSONObject jsonObject = JSONObject.parseObject(JSON_OBJ_STR);

    System.out.println("studentName:  " + jsonObject.getString("studentName") + ":" + "  studentAge:  "
            + jsonObject.getInteger("studentAge"));

}

/**
 * JSONObject到json字符串-简单对象型的转换
 */
@Test
public void testJSONObjectToJSONStr() {

    //已知JSONObject,目标要转换为json字符串
    JSONObject jsonObject = JSONObject.parseObject(JSON_OBJ_STR);
    // 第一种方式
    String jsonString = JSONObject.toJSONString(jsonObject);

    // 第二种方式
    //String jsonString = jsonObject.toJSONString();
    System.out.println(jsonString);
}

2.1.2.json字符串(数组类型)与JSONArray之间的转换

/**
 * json字符串-数组类型到JSONArray的转换
 */
@Test
public void testJSONStrToJSONArray() {

    JSONArray jsonArray = JSONArray.parseArray(JSON_ARRAY_STR);

    //遍历方式1
    int size = jsonArray.size();
    for (int i = 0; i < size; i++) {

        JSONObject jsonObject = jsonArray.getJSONObject(i);
        System.out.println("studentName:  " + jsonObject.getString("studentName") + ":" + "  studentAge:  "
                + jsonObject.getInteger("studentAge"));
    }

    //遍历方式2
    for (Object obj : jsonArray) {

        JSONObject jsonObject = (JSONObject) obj;
        System.out.println("studentName:  " + jsonObject.getString("studentName") + ":" + "  studentAge:  "
                + jsonObject.getInteger("studentAge"));
    }
}

/**
 * JSONArray到json字符串-数组类型的转换
 */
@Test
public void testJSONArrayToJSONStr() {

    //已知JSONArray,目标要转换为json字符串
    JSONArray jsonArray = JSONArray.parseArray(JSON_ARRAY_STR);
    //第一种方式
    String jsonString = JSONArray.toJSONString(jsonArray);

    // 第二种方式
    //String jsonString = jsonArray.toJSONString(jsonArray);
    System.out.println(jsonString);
}

2.1.3.复杂json格式字符串与JSONObject之间的转换

/**
 * 复杂json格式字符串到JSONObject的转换
 */
@Test
public void testComplexJSONStrToJSONObject() {

    JSONObject jsonObject = JSONObject.parseObject(COMPLEX_JSON_STR);

    String teacherName = jsonObject.getString("teacherName");
    Integer teacherAge = jsonObject.getInteger("teacherAge");

    System.out.println("teacherName:  " + teacherName + "   teacherAge:  " + teacherAge);

    JSONObject jsonObjectcourse = jsonObject.getJSONObject("course");
     //获取JSONObject中的数据
    String courseName = jsonObjectcourse.getString("courseName");
    Integer code = jsonObjectcourse.getInteger("code");

    System.out.println("courseName:  " + courseName + "   code:  " + code);

    JSONArray jsonArraystudents = jsonObject.getJSONArray("students");

    //遍历JSONArray
    for (Object object : jsonArraystudents) {

        JSONObject jsonObjectone = (JSONObject) object;
        String studentName = jsonObjectone.getString("studentName");
        Integer studentAge = jsonObjectone.getInteger("studentAge");

        System.out.println("studentName:  " + studentName + "   studentAge:  " + studentAge);
    }
}

/**
 * 复杂JSONObject到json格式字符串的转换
 */
@Test
public void testJSONObjectToComplexJSONStr() {

   //复杂JSONObject,目标要转换为json字符串
    JSONObject jsonObject = JSONObject.parseObject(COMPLEX_JSON_STR);

    //第一种方式
    //String jsonString = JSONObject.toJSONString(jsonObject);

    //第二种方式
    String jsonString = jsonObject.toJSONString();
    System.out.println(jsonString);

}

2.2.JSON格式字符串与javaBean之间的转换

2.2.1.json字符串-简单对象型与javaBean之间的转换

/**
 * json字符串-简单对象到JavaBean之间的转换
 */
@Test
public void testJSONStrToJavaBeanObj() {

    //第一种方式
    JSONObject jsonObject = JSONObject.parseObject(JSON_OBJ_STR);

    String studentName = jsonObject.getString("studentName");
    Integer studentAge = jsonObject.getInteger("studentAge");

    //Student student = new Student(studentName, studentAge);

    //第二种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    //Student student = JSONObject.parseObject(JSON_OBJ_STR, new TypeReference<Student>() {});

    //第三种方式,使用Gson的思想
    Student student = JSONObject.parseObject(JSON_OBJ_STR, Student.class);

    System.out.println(student);
}

/**
 * JavaBean到json字符串-简单对象的转换
 */
@Test
public void testJavaBeanObjToJSONStr() {

    Student student = new Student("lily", 12);
    String jsonString = JSONObject.toJSONString(student);
    System.out.println(jsonString);
}

2.2.2.json字符串-数组类型与javaBean之间的转换

/**
 * json字符串-数组类型到JavaBean_List的转换
 */
@Test
public void testJSONStrToJavaBeanList() {

    //第一种方式
    JSONArray jsonArray = JSONArray.parseArray(JSON_ARRAY_STR);

    //遍历JSONArray
    List<Student> students = new ArrayList<Student>();
    Student student = null;
    for (Object object : jsonArray) {

        JSONObject jsonObjectone = (JSONObject) object;
        String studentName = jsonObjectone.getString("studentName");
        Integer studentAge = jsonObjectone.getInteger("studentAge");

        student = new Student(studentName,studentAge);
        students.add(student);
    }

    System.out.println("students:  " + students);

    //第二种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    List<Student> studentList = JSONArray.parseObject(JSON_ARRAY_STR, new TypeReference<ArrayList<Student>>() {});
    System.out.println("studentList:  " + studentList);

    //第三种方式,使用Gson的思想
    List<Student> studentList1 = JSONArray.parseArray(JSON_ARRAY_STR, Student.class);
    System.out.println("studentList1:  " + studentList1);

}

/**
 * JavaBean_List到json字符串-数组类型的转换
 */
@Test
public void testJavaBeanListToJSONStr() {

    Student student = new Student("lily", 12);
    Student studenttwo = new Student("lucy", 15);

    List<Student> students = new ArrayList<Student>();
    students.add(student);
    students.add(studenttwo);

    String jsonString = JSONArray.toJSONString(students);
    System.out.println(jsonString);

}

2.2.3.复杂json格式字符串与与javaBean之间的转换

/**
 * 复杂json格式字符串到JavaBean_obj的转换
 */
@Test
public void testComplexJSONStrToJavaBean(){

    //第一种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    Teacher teacher = JSONObject.parseObject(COMPLEX_JSON_STR, new TypeReference<Teacher>() {});
    System.out.println(teacher);

    //第二种方式,使用Gson思想
    Teacher teacher1 = JSONObject.parseObject(COMPLEX_JSON_STR, Teacher.class);
    System.out.println(teacher1);
}

/**
 * 复杂JavaBean_obj到json格式字符串的转换
 */
@Test
public void testJavaBeanToComplexJSONStr(){

    //已知复杂JavaBean_obj
    Teacher teacher = JSONObject.parseObject(COMPLEX_JSON_STR, new TypeReference<Teacher>() {});
    String jsonString = JSONObject.toJSONString(teacher);
    System.out.println(jsonString);
}

2.3.javaBean与json对象间的之间的转换

2.3.1.简单javaBean与json对象之间的转换

/**
 * 简单JavaBean_obj到json对象的转换
 */
@Test
public void testJavaBeanToJSONObject(){

    //已知简单JavaBean_obj
    Student student = new Student("lily", 12);

    //方式一
    String jsonString = JSONObject.toJSONString(student);
    JSONObject jsonObject = JSONObject.parseObject(jsonString);
    System.out.println(jsonObject);

    //方式二
    JSONObject jsonObject1 = (JSONObject) JSONObject.toJSON(student);
    System.out.println(jsonObject1);
}

/**
 * 简单json对象到JavaBean_obj的转换
 */
@Test
public void testJSONObjectToJavaBean(){

    //已知简单json对象
    JSONObject jsonObject = JSONObject.parseObject(JSON_OBJ_STR);

    //第一种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    Student student = JSONObject.parseObject(jsonObject.toJSONString(), new TypeReference<Student>() {});
    System.out.println(student);

    //第二种方式,使用Gson的思想
    Student student1 = JSONObject.parseObject(jsonObject.toJSONString(), Student.class);
    System.out.println(student1);
}

2.3.2.JavaList与JsonArray之间的转换

/**
 * JavaList到JsonArray的转换
 */
@Test
public void testJavaListToJsonArray() {

    //已知JavaList
    Student student = new Student("lily", 12);
    Student studenttwo = new Student("lucy", 15);

    List<Student> students = new ArrayList<Student>();
    students.add(student);
    students.add(studenttwo);

    //方式一
    String jsonString = JSONArray.toJSONString(students);
    JSONArray jsonArray = JSONArray.parseArray(jsonString);
    System.out.println(jsonArray);

    //方式二
    JSONArray jsonArray1 = (JSONArray) JSONArray.toJSON(students);
    System.out.println(jsonArray1);
}

/**
 * JsonArray到JavaList的转换
 */
@Test
public void testJsonArrayToJavaList() {

    //已知JsonArray
    JSONArray jsonArray = JSONArray.parseArray(JSON_ARRAY_STR);

    //第一种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    ArrayList<Student> students = JSONArray.parseObject(jsonArray.toJSONString(),
            new TypeReference<ArrayList<Student>>() {});

    System.out.println(students);

    //第二种方式,使用Gson的思想
    List<Student> students1 = JSONArray.parseArray(jsonArray.toJSONString(), Student.class);
    System.out.println(students1);
}

2.3.3.复杂JavaBean_obj与json对象之间的转换

/**
 * 复杂JavaBean_obj到json对象的转换
 */
@Test
public void testComplexJavaBeanToJSONObject() {

    //已知复杂JavaBean_obj
    Student student = new Student("lily", 12);
    Student studenttwo = new Student("lucy", 15);

    List<Student> students = new ArrayList<Student>();
    students.add(student);
    students.add(studenttwo);
    Course course = new Course("english", 1270);

    Teacher teacher = new Teacher("crystall", 27, course, students);

    //方式一
    String jsonString = JSONObject.toJSONString(teacher);
    JSONObject jsonObject = JSONObject.parseObject(jsonString);
    System.out.println(jsonObject);

    //方式二
    JSONObject jsonObject1 = (JSONObject) JSONObject.toJSON(teacher);
    System.out.println(jsonObject1);

}

/**
 * 复杂json对象到JavaBean_obj的转换
 */
@Test
public void testComplexJSONObjectToJavaBean() {

    //已知复杂json对象
    JSONObject jsonObject = JSONObject.parseObject(COMPLEX_JSON_STR);

    //第一种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    Teacher teacher = JSONObject.parseObject(jsonObject.toJSONString(), new TypeReference<Teacher>() {});
    System.out.println(teacher);

    //第二种方式,使用Gson的思想
    Teacher teacher1 = JSONObject.parseObject(jsonObject.toJSONString(), Teacher.class);
    System.out.println(teacher1);
}

3.源码

本篇博客的源码都在我的Github上,FastJsonDemo,欢迎大家Fork and Star!

Maven引入

<dependency>

<groupId>com.alibaba</groupId>

<artifactId>fastjson</artifactId>

<version>1.2.37</version>

</dependency>

常用api

1. 将对象序列化成json字符串

String com.alibaba.fastjson.JSON.toJSONString(Object object)

2. 将json字符串反序列化成对象

<T> Project com.alibaba.fastjson.JSON.parseObject(String text, Class<T> clazz)

3. 将json字符串反序列化成JSON对象

JSONObject com.alibaba.fastjson.JSON.parseObject(String text)

4.根据key 得到json中的json数组

JSONArray com.alibaba.fastjson.JSONObject.getJSONArray(String key)

5. 根据下标拿到json数组的json对象

JSONObject com.alibaba.fastjson.JSONArray.getJSONObject(int index)

6.. 根据key拿到json的字符串值

String com.alibaba.fastjson.JSONObject.getString(String key)

7. 根据key拿到json的int值

int com.alibaba.fastjson.JSONObject.getIntValue(String key)

8. 根据key拿到json的boolean值

boolean com.alibaba.fastjson.JSONObject.getBooleanValue(String key)

实例说明

Project类

package com.json;

import java.util.List;

public class Project {
    String pjName;
    boolean waibao;
    public boolean isWaibao() {
        return waibao;
    }
    public void setWaibao(boolean waibao) {
        this.waibao = waibao;
    }
    List<Factory> l_factory;
    //List<Worker> worker;
    public String getPjName() {
        return pjName;
    }
    public void setPjName(String pjName) {
        this.pjName = pjName;
    }
    public List<Factory> getL_factory() {
        return l_factory;
    }
    public void setL_factory(List<Factory> l_factory) {
        this.l_factory = l_factory;
    }

}

Factory类

package com.json;

import java.util.List;

public class Factory {

    String fcName;
    List<Worker> l_worker;
    public String getFcName() {
        return fcName;
    }
    public void setFcName(String fcName) {
        this.fcName = fcName;
    }
    public List<Worker> getL_worker() {
        return l_worker;
    }
    public void setL_worker(List<Worker> l_worker) {
        this.l_worker = l_worker;
    }

}

Worker类

package com.json;

public class Worker {

    String name;
    String sex;
    int age;
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }

}

测试类

package com.json;

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

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

public class TestFastJson {

    public static void main(String args[]) {
        TestFastJson tfj = new TestFastJson();
        Project prj = tfj.init();
        String json= tfj.getJsonString(prj);
        System.out.println("json="+json);
        //json={"l_factory":[{"fcName":"东软","l_worker":[{"age":30,"name":"乔佳飞","sex":"男"},{"age":25,"name":"李帅飞","sex":"女"}]},{"fcName":"亚信","l_worker":[{"age":26,"name":"王新峰","sex":"男"},{"age":0}]}],"pjName":"接口自动化","waibao":true}
        System.out.println("waibao="+tfj.getJsonValueObj(json, "waibao", Boolean.class));
        //waibao=true
        JSONArray array = (JSONArray) tfj.getJsonValueObj(json, "l_factory", JSONArray.class);
        System.out.println("array="+array.toString());
        //array=[{"fcName":"东软","l_worker":[{"sex":"男","name":"乔佳飞","age":30},{"sex":"女","name":"李帅飞","age":25}]},{"fcName":"亚信","l_worker":[{"sex":"男","name":"王新峰","age":26},{"age":0}]}]
        String jsonArr = tfj.getJsonArrayValue(array, 0, "fcName");
        System.out.println("fcName="+jsonArr);
        //fcName=东软
        JSONArray array2 = tfj.getJsonArrayValueIsArray(array, 0, "l_worker");
        System.out.println("array2="+array2.toString());
        //array2=[{"sex":"男","name":"乔佳飞","age":30},{"sex":"女","name":"李帅飞","age":25}]
        String json2 = tfj.getJsonArrayValue(array2, 0);
        System.out.println("json2="+json2);
        //json2={"sex":"男","name":"乔佳飞","age":30}

        /*以下输出
        name=乔佳飞
        sex=男
        age=30
        jsonArr2=男

         * */
        System.out.println("name="+tfj.getJsonValueObj(json2, "name", String.class));
        System.out.println("sex="+tfj.getJsonValueObj(json2, "sex", String.class));
        System.out.println("age="+tfj.getJsonValueObj(json2, "age", Integer.class));

        String jsonArr2 = tfj.getJsonArrayValue(array2, 0, "sex");
        System.out.println("jsonArr2="+jsonArr2);

        /*以下输出
         接口自动化
        东软
        乔佳飞
         */
        System.out.println(tfj.getJsonValue(json));
        System.out.println(tfj.getJsonValue(json,"l_factory"));
        System.out.println(tfj.getJsonValue(json,"l_factory","l_worker"));

    }
    public static void main1(String args[]) {
        TestFastJson tfj = new TestFastJson();
        Project prj = tfj.init();
        String json= tfj.getJsonString(prj);
        prj.setPjName("序列化后修改pjname");
        System.out.println(prj.getPjName());//序列化后修改pjname
        Project po = JSON.parseObject(json,Project.class);
        System.out.println(po.getPjName());//接口自动化
    }

    public void tt(Class clazz) {
        System.out.println(clazz.getSimpleName());
        if(clazz.getName().equals("String")) {
            System.out.println("stringllala");
        }
    }
    public Project init() {
        Project pj = new Project();
        Factory ft1 = new Factory();
        Factory ft2 = new Factory();
        Worker wk1 = new Worker();
        wk1.setName("乔佳飞");
        wk1.setSex("男");
        wk1.setAge(30);

        Worker wk2 = new Worker();
        wk2.setName("李帅飞");
        wk2.setSex("女");
        wk2.setAge(25);

        Worker wk3 = new Worker();
        wk3.setName("魏晓博");
        wk3.setSex("男");
        wk3.setAge(27);

        Worker wk4 = new Worker();
        wk3.setName("王新峰");
        wk3.setSex("男");
        wk3.setAge(26);

        List<Worker> workers1 = new ArrayList<Worker>();
        workers1.add(wk1);
        workers1.add(wk2);

        List<Worker> workers2 = new ArrayList<Worker>();
        workers2.add(wk3);
        workers2.add(wk4);

        ft1.setFcName("东软");
        ft1.setL_worker(workers1);

        ft2.setFcName("亚信");
        ft2.setL_worker(workers2);

        List<Factory> factorys = new ArrayList<Factory>();
        factorys.add(ft1);
        factorys.add(ft2);

        pj.setPjName("接口自动化");
        pj.setWaibao(true);
        pj.setL_factory(factorys);

        return pj;
    }

    /**
     *
     * 将对象转换成json
     * */
    public String getJsonString(Object obj) {
        String json= JSON.toJSONString(obj);
        return json;
    }

    /**
     * 根据key得到json的value
     * */
    public String getJsonValue(String json) {
        JSONObject jo = JSON.parseObject(json);
        String value = jo.getString("pjName");
        return value;
    }

    /**
     * 根据key得到json的集合
     * */
    public JSONArray getJsonArray(String json, String key) {
        JSONObject jo = JSON.parseObject(json);

        JSONArray array = jo.getJSONArray(key);

        return array;
    }

    /**
     * 根据下标得到json数组的值
     * */
    public String getJsonArrayValue(JSONArray array, int index) {
        JSONObject jo_fc = array.getJSONObject(index);
        String json = jo_fc.toJSONString();
        return json;
    }

    /**
     * 根据下标得到json数组的值，再根据key得到该值的value，该值类型是String
     * */
    public String getJsonArrayValue(JSONArray array, int index, String key) {
        JSONObject jo_fc = array.getJSONObject(index);
        String value = jo_fc.getString(key);
        return value;
    }
    /**
     * 根据下标得到json数组的值，再根据key得到该值的value,该值类型是JSONArray
     * */
    public JSONArray getJsonArrayValueIsArray(JSONArray array, int index, String key) {
        JSONObject jo_fc = array.getJSONObject(index);
        JSONArray arrayNew = jo_fc.getJSONArray(key);
        return arrayNew;
    }
    /**
     * 根据对象的类型，自动识别获取该对象的值
     * */
    public Object getJsonValueObj(String json, String key, Class clazz) {
        JSONObject jo = JSON.parseObject(json);
        if(clazz.getSimpleName().equals("String")) {
            String value = jo.getString(key);
            return value;
        }else if(clazz.getSimpleName().equals("Integer")) {
            Integer value = jo.getInteger(key);
            return value;
        }else if (clazz.getSimpleName().equals("Boolean")) {
            Boolean value = jo.getBoolean(key);
            return value;
        }else if(clazz.getSimpleName().equals("JSONArray")) {
            JSONArray array = jo.getJSONArray(key);
            return array;
        }
        else {
            return "error, 暂不支持的类型:"+clazz.toString();
        }        

    }

    public String getJsonValue(String json, String key) {
        JSONObject jo = JSON.parseObject(json);

        JSONArray array = jo.getJSONArray(key);
        JSONObject jo_fc = array.getJSONObject(0);
        String value = jo_fc.getString("fcName");
        return value;
    }

    public String getJsonValue(String json, String key, String keyW) {
        JSONObject jo = JSON.parseObject(json);

        JSONArray array = jo.getJSONArray(key);
        JSONObject jo_fc = array.getJSONObject(0);
        JSONArray arrayW = jo_fc.getJSONArray(keyW);
        JSONObject jo_wk = arrayW.getJSONObject(0);
        String value = jo_wk.getString("name");
        int age = jo_wk.getIntValue("age");
        //System.out.println(age);
        return value;
    }
}

参考：com.alibaba的fastjson简介

参考：高性能JSON框架之FastJson的简单使用