转自https://www.cnblogs.com/wenqiangit/p/11575508.html
我们在日常开发中少不了和JSON数据打交道，那么我们来看看JAVA中常用的JSON解析方式。
1、JSON官方 脱离框架使用
2、GSON
3、FastJSON 有问题
4、jackson 常用
JSON操作涉及到的类：
public classStudent{
private int id;
private String name;
private int age;
publicintgetId(){
return id;
}
publicvoidsetId(intid){
this.id = id;
}
publicStringgetName(){
return name;
}
publicvoidsetName(String name){
this.name = name;
}
publicintgetAge(){
return age;
}
publicvoidsetAge(intage){
this.age = age;
}
publicStudent(intid, String name,intage){
super();
this.id = id;
this.name = name;
this.age = age;
}
publicStudent(){
super();
}
@Override publicStringtoString(){
return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";
}
}
public classGrade{
private int id;
private String name;
private ArrayList<Student> stus;
publicGrade(intid, String name, ArrayList stus){
super();
this.id = id;
this.name = name;
this.stus = stus;
}
publicGrade(){
super();
}
@Override publicStringtoString(){
return "Grade [id=" + id + ", name=" + name + ", stus=" + stus + "]";
}
publicintgetId(){
return id;
}
publicvoidsetId(intid){
this.id = id;
}
publicStringgetName(){
return name;
}
publicvoidsetName(String name){
this.name = name;
}
publicArrayListgetStus(){
return stus;
}
publicvoidsetStus(ArrayList<Student> stus){
this.stus = stus;
}
}
JSON官方的解析最具有通用性，但是有点小麻烦。
package cn.itcast.test;import net.sf.json.JSONArray;import net.sf.json.JSONObject;import org.junit.Test;import java.util.ArrayList;public classJsonTest{
@Test publicvoidtest1(){
String json1 = "{'id':1,'name':'JAVAEE-1703','stus':[{'id':101,'name':'刘一','age':16},{'id':102,'name':'刘二','age':23}]}";
//数组 String json2 = "['北京','天津','杭州']";// JSONObject jObject = new JSONObject(json1); JSONObject jsonObject = JSONObject.fromObject(json1);// System.out.println(jsonObject);// Map<String,Object> map = jsonObject;// for (Map.Entry<String, Object> entry : map.entrySet()) {// System.out.println(entry.getKey());// System.out.println(entry.getValue());// System.out.println("=========");// } Grade grade = new Grade();
grade.setId(jsonObject.getInt("id"));
grade.setName(jsonObject.getString("name"));
ArrayList<Student> students = new ArrayList<>();
grade.setStus(students);
JSONArray stus = jsonObject.getJSONArray("stus");
for (Object o : stus) {// System.out.println(o); JSONObject jsonObject1 = JSONObject.fromObject(o);
Student student = new Student(jsonObject1.getInt("id"), jsonObject1.getString("name"), jsonObject1.getInt("age"));
grade.getStus().add(student);
}
System.out.println(grade);
}
@Test publicvoidtest2(){
JSONObject jsonObject = new JSONObject();
jsonObject.put("id", 100);
jsonObject.put("name", "二弟");
jsonObject.put("age", 30);
JSONObject jsonObject1 = new JSONObject();
jsonObject1.put("id", 102);
jsonObject1.put("name", "狗蛋");
jsonObject1.put("age", 10);
JSONArray jsonArray = new JSONArray();
jsonArray.add(jsonObject);
jsonArray.add(jsonObject1);
System.out.println(jsonArray);
}
}
GSON解析是谷歌的，也比较好用
public classGSONTest{
//解析 @Test publicvoidtest1(){
// 对象嵌套数组嵌套对象 String json1 = "{'id':1,'name':'JAVAEE-1703','stus':[{'id':101,'name':'刘一','age':16}]}";
// 数组 String json2 = "['北京','天津','杭州']";
Gson gson=new Gson();
//1、 //解析对象：第一个参数：待解析的字符串 第二个参数结果数据类型的Class对象 Grade grade=gson.fromJson(json1, Grade.class);
System.out.println(grade);
//2、 //解析数组要求使用Type ArrayList<String> list=gson.fromJson(json2,
new TypeToken<ArrayList<String>>(){}.getType());
System.out.println(list);
}
//生成 @Test publicvoidtest2(){
ArrayList<Student> list=new ArrayList<>();
for(int i=1;i<3;i++){
list.add(new Student(101+i, "码子", 20+i));
}
Grade grade=new Grade(100001,"张三", list);
Gson gson=new Gson();
//将对象转换为诶JSON格式字符串 String json=gson.toJson(grade);
System.out.println(json);
}
}
FastJSON是阿里巴巴的产品，效率最高
public classFASTJson{
//解析 @Test publicvoidtest1(){
// 对象嵌套数组嵌套对象 String json1 = "{'id':1,'name':'JAVAEE-1703','stus':[{'id':101,'name':'刘铭','age':16}]}";
// 数组 String json2 = "['北京','天津','杭州']";
//1、 //静态方法 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 publicvoidtest2(){
ArrayList<Student> list=new ArrayList<>();
for(int i=1;i<3;i++){
list.add(new Student(101+i, "码子", 20+i));
}
Grade grade=new Grade(100001,"张三", list);
String json=JSON.toJSONString(grade);
System.out.println(json);
}
}
jackSon解析JSON，SpringMVC内置的解析器就是这个
package cn.itcast.test;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.core.type.TypeReference;import com.fasterxml.jackson.databind.ObjectMapper;import org.junit.Test;import java.io.IOException;import java.util.ArrayList;import java.util.List;public classjackSonTest{
@Test publicvoidtest1()throwsIOException{
// 对象嵌套数组嵌套对象 String json1 = "{\"id\":1,\"name\":\"JAVAEE-1703\",\"stus\":[{\"id\":101,\"name\":\"刘一\",\"age\":16}]}";
// 数组 String json2 = "[\"北京\",\"天津\",\"杭州\"]";
ObjectMapper mapper = new ObjectMapper();
Grade grade = mapper.readValue(json1, Grade.class);
System.out.println(grade);
List<String> list = mapper.readValue(json2, new TypeReference<List<String>>() {
});
System.out.println(list);
}
@Test publicvoidtest2()throwsJsonProcessingException{
ArrayList<Student> students = new ArrayList<>();
for (int i = 0; i < 3; i++) {
students.add(new Student(100 + i, "二稿" + i, 1000 + i));
}
Grade grade = new Grade(22, "语文", students);// System.out.println(grade); ObjectMapper objectMapper = new ObjectMapper();
String s = objectMapper.writeValueAsString(grade);
System.out.println(s);
}
}
除了JSON官方的对类没有要求，剩下的都要求是标准的类，否则无法解析，因为都用到了反射。
