高性能JSON框架之FastJson的简单使用
转载自:https://segmentfault.com/a/1190000011212806
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速度快,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
2.FastJson的用法
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;
public class TestFastJson {
// json字符串-简单对象型
private static final String JSON_OBJ_STR = "{\"studentName\":\"lily\",\"studentAge\":12}";
// private static final String JSON_OBJ_STR2 =
// "{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}]}";
/**
* json字符串-简单对象型到JSONObject的转换 JSONObject.parseObject(Str)
*/
@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 JSONObject.toJSONString(jsonObject)
*/
@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);
}
/**
* json字符串-数组类型到JSONArray的转换 JSONArray.parseArray(Str)
*/
@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 JSONArray.toJSONString(jsonArray)
*/
@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);
}
/**
* 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);
}
/**
* json字符串-简单对象到JavaBean之间的转换 JSONObject.parseObject(JSON_OBJ_STR,
* Student.class)
*/
@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 need default constructor
Student student = JSONObject.parseObject(JSON_OBJ_STR, Student.class);
System.out.println(student.toString());
}
/**
* 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);
}
/**
* 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);
}
/**
* 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);
}
/**
* 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);
}
/**
* 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);
}
/**
* 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);
}
}
/**
* @author Zhangdi class Student
*/
class Student {
private String studentName;
private Integer studentAge;
protected Student() {
super();
}
protected Student(String studentName, Integer studentAge) {
super();
this.studentName = studentName;
this.studentAge = studentAge;
}
public String getStudentName() {
return studentName;
}
public void setStudentName(String studentName) {
this.studentName = studentName;
}
public Integer getStudentAge() {
return studentAge;
}
public void setStudentAge(Integer studentAge) {
this.studentAge = studentAge;
}
@Override
public String toString() {
return "Student [studentName=" + studentName + ", studentAge=" + studentAge + "]";
}
}
/**
* @author Zhangdi Teacher
*/
class Teacher {
private String teacherName;
private Integer teacherAge;
private Course course;
private List<Student> students;
protected Teacher() {
super();
// TODO Auto-generated constructor stub
}
protected Teacher(String teacherName, Integer teacherAge) {
super();
this.teacherName = teacherName;
this.teacherAge = teacherAge;
}
public Teacher(String teacherName, int teacherAge, Course course, List<Student> students) {
this.teacherName = teacherName;
this.teacherAge = teacherAge;
this.course = course;
this.students = students;
}
public String getTeacherName() {
return teacherName;
}
public void setTeacherName(String teacherName) {
this.teacherName = teacherName;
}
public Integer getTeacherAge() {
return teacherAge;
}
public void setTeacherAge(Integer teacherAge) {
this.teacherAge = teacherAge;
}
@Override
public String toString() {
return "Teacher [teacherName=" + teacherName + ", teacherAge=" + teacherAge + "]";
}
}
class Course{
private String courseName;
private Integer code;
protected Course() {
super();
}
protected Course(String courseName, Integer code) {
super();
this.courseName = courseName;
this.code = code;
}
public String getCourseName() {
return courseName;
}
public void setCourseName(String courseName) {
this.courseName = courseName;
}
public Integer getCode() {
return code;
}
public void setCode(Integer code) {
this.code = code;
}
}
20190625 update:
public static String getArrJson() {
JSONObject jsonObject = new JSONObject();
List<Map<String, Object>> list = new ArrayList<>();
Map<String, Object> map = null;
for (int i = 1; i < 5; i++) {
map = new HashMap<>();
map.put("name", "name" + i);
map.put("age", "age" + i);
list.add(map);
}
jsonObject.put("result_data", list);
return jsonObject.toJSONString();
}
