Fastjson JSON 操作
1. Java环境下使用
1.1 Json字符串转为json对象
将下面的json字符串转为json对象，同时对该对象析构。
{
"code": "200",
"message": "SUCCESS",
"data": [
{
"name": "lisi",
"age": 32
},
{
"name": "liwu",
"age": 23
}
]
}
程序：
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import org.junit.Test;
public class Exercise {
@Test
public void stringToJson() {
// json压缩转义网址：https://www.bejson.com/zhuanyi/
String jsonStr = "{\"code\":200,\"message\":\"SUCCESS\",\"data\":[{\"name\":\"lisi\",\"age\":32}," +
"{\"name\":\"liwu\",\"age\":23}]}";
JSONObject parse = (JSONObject) JSON.parse(jsonStr);
int code = (int) parse.get("code");
String message = (String) parse.get("message");
System.out.println(code);
System.out.println(message);
JSONArray dataArray = parse.getJSONArray("data");
for (Object obj : dataArray) {
JSONObject jsonObject = (JSONObject) JSONObject.toJSON(obj);
String name = (String) jsonObject.get("name");
int age = (int) jsonObject.get("age");
System.out.println("[name: " + name + ", age: " + age + "]");
}
}
}
运行结果：
200
SUCCESS
[name: lisi, age: 32]
[name: liwu, age: 23]
1.2 Bean对象转为json对象
程序1：
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import org.junit.Test;
class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
/* public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}*/
}
public class Exercise {
@Test
public void stringToJson() {
JSONObject jsonObject = new JSONObject();
JSONArray jsonArray = new JSONArray();
jsonObject.put("code", 200);
jsonObject.put("message", "SUCCESS");
jsonArray.add(new Person("lisi", 32));
jsonArray.add(new Person("liwu", 23));
jsonObject.put("data", jsonArray);
System.out.println(jsonArray);
System.out.println(jsonObject);
System.out.println("-----------");
int code = (int) jsonObject.get("code");
String message = (String) jsonObject.get("message");
System.out.println(code);
System.out.println(message);
JSONArray dataArray = jsonObject.getJSONArray("data");
for (Object obj : dataArray) {
JSONObject json = (JSONObject) JSONObject.toJSON(obj);
String name = (String) json.get("name");
int age = (int) json.get("age");
System.out.println("[name: " + name + ", age: " + age + "]");
}
}
}
运行结果：
[{},{}]
{"code":200,"data":[{},{}],"message":"SUCCESS"}
-----------
200
SUCCESS
java.lang.NullPointerException
at cn.ouyxy.operation.Exercise.stringToJson(Exercise.java:56)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at...
程序2：
class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
public class Exercise {
@Test
public void stringToJson() {
JSONObject jsonObject = new JSONObject();
JSONArray jsonArray = new JSONArray();
jsonObject.put("code", 200);
jsonObject.put("message", "SUCCESS");
jsonArray.add(new Person("lisi", 32));
jsonArray.add(new Person("liwu", 23));
jsonObject.put("data", jsonArray);
System.out.println(jsonArray);
System.out.println(jsonObject);
System.out.println("-----------");
int code = (int) jsonObject.get("code");
String message = (String) jsonObject.get("message");
System.out.println(code);
System.out.println(message);
JSONArray dataArray = jsonObject.getJSONArray("data");
for (Object obj : dataArray) {
JSONObject json = (JSONObject) JSONObject.toJSON(obj);
String name = (String) json.get("name");
int age = (int) json.get("age");
System.out.println("[name: " + name + ", age: " + age + "]");
}
}
}
运行结果：
[{"age":32,"name":"lisi"},{"age":23,"name":"liwu"}]
{"code":200,"data":[{"age":32,"name":"lisi"},{"age":23,"name":"liwu"}],"message":"SUCCESS"}
-----------
200
SUCCESS
[name: lisi, age: 32]
[name: liwu, age: 23]
2. Scala环境下使用
2.1 Json字符串转为json对象
程序：
import com.alibaba.fastjson.{JSON, JSONObject}
object Exercise2 {
def main(args: Array[String]): Unit = {
val jsonStr =
"""
|{
| "code": "200",
| "message": "SUCCESS",
| "data": [
| {
| "name": "lisi",
| "age": 32
| },
| {
| "name": "liwu",
| "age": 23
| }
| ]
|}
""".stripMargin
val jsonObject = JSON.parse(jsonStr).asInstanceOf[JSONObject]
val code = jsonObject.get("code")
val message = jsonObject.get("message")
println(code)
println(message)
val data = jsonObject.getJSONArray("data")
for(i <- 0 until data.size){
val obj = data.getJSONObject(i)
val name = obj.get("name")
val age = obj.get("age")
println("[name: " + name + ", age: " + age + "]")
}
}
}
运行结果：
200
SUCCESS
[name: lisi, age: 32]
[name: liwu, age: 23]
2.2 fastjson序列化scala对象
程序1：
import com.alibaba.fastjson.JSON
case class Cat(name: String, age: Int)
object Exercise2 {
def main(args: Array[String]): Unit = {
val cat = Cat("mao1", 1)
val str = JSON.toJSONString(cat, false)
println(str)
}
}
结果：
{}
结果解析：
fastjson默认是基于方法clz.getMethods()进行字段查找过滤的，通过getter方法查找字段信息；而这里使用case class方式构建对象，没有setter和getter方法，使用默认的配置序列化对象，导致错误。根据这个思路，为Cat类加上 getter，可以解决问题，如程序2。
程序2：
import com.alibaba.fastjson.JSON
class Cat(_name: String, _age: Int){
var name: String = _name
val age: Int = _age
def getName = this.name
def getAge = this.age
}
object Cat{
def apply(_name: String, _age: Int): Cat = new Cat(_name, _age)
}
object Exercise2 {
def main(args: Array[String]): Unit = {
val cat = Cat("mao1", 1)
val str = JSON.toJSONString(cat, false)
println(str)
}
}
运行结果：
{"age":1,"name":"mao1"}
fastjson 同时提供了基于字段的方式clz.getDeclaredFields()进行查找过滤。修改后的代码如程序3:
程序3：
import com.alibaba.fastjson.JSON
import com.alibaba.fastjson.serializer.SerializeConfig
case class Cat(name: String, age: Int)
object Exercise2 {
def main(args: Array[String]): Unit = {
val cat = Cat("mao1", 1)
val conf = new SerializeConfig(true)
val str = JSON.toJSONString(cat, conf)
println(str)
}
}
结果：
{"age":1,"name":"mao1"}
2.3 scala对象转为json对象
程序：
import com.alibaba.fastjson.{JSON, JSONArray}
import com.alibaba.fastjson.serializer.SerializeConfig
import scala.collection.JavaConversions._
case class Cat(name: String, age: Int)
object Exercise2 {
def main(args: Array[String]): Unit = {
val conf = new SerializeConfig(true)
val catList = List(JSON.toJSON(Cat("mao1", 1), conf), JSON.toJSON(Cat("mao2", 1), conf))
val jsonArray: JSONArray = new JSONArray(catList)
println(jsonArray)
}
}
运行结果：
[{"name":"mao1","age":1},{"name":"mao2","age":1}]
