我們在日常開發中少不了和JSON數據打交道,那麼我們來看看JAVA中常用的JSON解析方式。
1、JSON官方
2、GSON
3、FastJSON
4、jackson
JSON操作涉及到的類:
public class Student {
private int id;
private String name;
private int age;
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 getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Student(int id, String name, int age) {
super();
this.id = id;
this.name = name;
this.age = age;
}
public Student() {
super();
}
@Override
public String toString() {
return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";
}
}
public class Grade {
private int id;
private String name;
private ArrayList<Student> stus;
public Grade(int id, String name, ArrayList<Student> stus) {
super();
this.id = id;
this.name = name;
this.stus = stus;
}
public Grade() {
super();
}
@Override
public String toString() {
return "Grade [id=" + id + ", name=" + name + ", stus=" + stus + "]";
}
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 ArrayList<Student> getStus() {
return stus;
}
public void setStus(ArrayList<Student> stus) {
this.stus = stus;
}
}
JSON官方的解析最具有通用性,但是有點小麻煩。
public class JSONTest {
//解析JSON
@Test
public void test1() throws JSONException{
//對象嵌套數組嵌套對象
String json1="{'id':1,'name':'JAVAEE-1703','stus':[{'id':101,'name':'劉一','age':16}]}";
//數組
String json2="['北京','天津','杭州']";
//1、
//解析第一層---對象
JSONObject jObject1=new JSONObject(json1);
Grade grade=new Grade();
grade.setId(jObject1.getInt("id"));
grade.setName(jObject1.getString("name"));
ArrayList<Student> stus=new ArrayList<>();
grade.setStus(stus);
//解析第二層----數組
JSONArray jsonArray2=jObject1.getJSONArray("stus");
//遍歷數組獲取元素----對象
for(int i=0;i<jsonArray2.length();i++){
//解析第三層----對象
JSONObject jObject3=jsonArray2.getJSONObject(i);
Student student=new Student(jObject3.getInt("id"), jObject3.getString("name"), jObject3.getInt("age"));
grade.getStus().add(student);
}
System.out.println(grade);
//獲取當前對象的所有屬性的迭代器對象
// Iterator<String> iterator=jObject1.keys();
// while (iterator.hasNext()) {
// String key = iterator.next();
// System.out.println("屬性:"+key);
// }
//2、
//獲取數組對象
JSONArray jArray=new JSONArray(json2);
ArrayList<String> list=new ArrayList<>();
//遍歷獲取元素
for(int i=0;i<jArray.length();i++){
//jArray.optString(i);//等價於getXXX
list.add(jArray.getString(i));
}
System.out.println("解析結果:"+list);
}
//生成JSON
@Test
public void test2() throws JSONException{
JSONObject jo1=new JSONObject();
jo1.put("id", 1001);
jo1.put("name", "範老");
jo1.put("age", 20);
JSONObject jo2=new JSONObject();
jo2.put("id", 1002);
jo2.put("name", "平平");
jo2.put("age", 19);
JSONArray ja2=new JSONArray();
ja2.put(jo1);
ja2.put(jo2);
JSONObject jo3=new JSONObject();
jo3.put("id", 11);
jo3.put("name", "JAVAEE-1704");
jo3.put("stus",ja2);
String json=jo3.toString();
System.out.println(json);
}
}
GSON解析是谷歌的,也比較好用
public class GSONTest {
//解析
@Test
public void test1() {
// 對象嵌套數組嵌套對象
String json1 = "{'id':1,'name':'JAVAEE-1703','stus':[{'id':101,'name':'劉一','age':16}]}";
// 數組
String json2 = "['北京','天津','杭州']";
Gson gson=new Gson();
//1、
//解析對象:第一個參數:待解析的字符串 第二個參數結果數據類型的Class對象
Grade grade=gson.fromJson(json1, Grade.class);
System.out.println(grade);
//2、
//解析數組要求使用Type
ArrayList<String> list=gson.fromJson(json2,
new TypeToken<ArrayList<String>>(){}.getType());
System.out.println(list);
}
//生成
@Test
public void test2(){
ArrayList<Student> list=new ArrayList<>();
for(int i=1;i<3;i++){
list.add(new Student(101+i, "碼子", 20+i));
}
Grade grade=new Grade(100001,"張三", list);
Gson gson=new Gson();
//將對象轉換爲誒JSON格式字符串
String json=gson.toJson(grade);
System.out.println(json);
}
}
FastJSON是阿里巴巴的產品,效率最高
public class FASTJson {
//解析
@Test
public void test1() {
// 對象嵌套數組嵌套對象
String json1 = "{'id':1,'name':'JAVAEE-1703','stus':[{'id':101,'name':'劉銘','age':16}]}";
// 數組
String json2 = "['北京','天津','杭州']";
//1、
//靜態方法
Grade grade=JSON.parseObject(json1, Grade.class);
System.out.println(grade);
//2、
List<String> list=JSON.parseArray(json2, String.class);
System.out.println(list);
}
//生成
@Test
public void test2(){
ArrayList<Student> list=new ArrayList<>();
for(int i=1;i<3;i++){
list.add(new Student(101+i, "碼子", 20+i));
}
Grade grade=new Grade(100001,"張三", list);
String json=JSON.toJSONString(grade);
System.out.println(json);
}
}
jackSon解析JSON,SpringMVC內置的解析器就是這個
public class JackSonTest {
//解析
@Test
public void test1() throws Exception{
// 對象嵌套數組嵌套對象
String json1 = "{\"id\":1,\"name\":\"JAVAEE-1703\",\"stus\":[{\"id\":101,\"name\":\"劉一\",\"age\":16}]}";
// 數組
String json2 = "[\"北京\",\"天津\",\"杭州\"]";
//1、
ObjectMapper mapper=new ObjectMapper();
Grade grade=mapper.readValue(json1, Grade.class);
System.out.println(grade);
//2、
ArrayList<String> list=mapper.readValue(json2,
new TypeReference<ArrayList<String>>() {
});
System.out.println(list);
}
//生成
@Test
public void test2() throws JsonProcessingException{
ArrayList<Student> list=new ArrayList<>();
for(int i=1;i<3;i++){
list.add(new Student(101+i, "碼子", 20+i));
}
Grade grade=new Grade(100001,"張三", list);
ObjectMapper mapper=new ObjectMapper();
//將對象轉換爲JSON格式字符串
String json=mapper.writeValueAsString(grade);
System.out.println(json);
}
}