Android GSON使用

刺骨的言语ヽ痛彻心扉 2023-06-10 12:25 44阅读 0赞

# Android GSON使用 #

> 使用场景及作用：Gson 是用来解析和生成Json，在实际项目中广泛使用。注意定义定对像的属性值必须和json中的保持一致，不然会解析失败。当然这就要求后台命名规范。

## 集成 ##

dependencies {
      implementation 'com.google.code.gson:gson:2.8.6'
    }

## 一、对象转Json ##

new Gson().toJson(obj)

## 二、Json转对象 ##

new Gson().fromJson(String json, Class<T> classOfT)

## 三、测试结果 ##

import androidx.appcompat.app.AppCompatActivity;
    
    import android.os.Bundle;
    import android.util.Log;
    
    import com.google.gson.Gson;
    
    import java.util.ArrayList;
    import java.util.List;
    
    /**
     * @author by t, Date on 2019-10-23.
     * note: Gson使用
     */
    public class MainActivity extends AppCompatActivity {
    
        private final String TAG = "MainActivity";
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            Gson gson = new Gson();
    
            Person person = new Person();
            person.setName("张三");
            person.setAge(22);
    
            Log.d(TAG, "toJson:" + gson.toJson(person));
    
            String jsonStr = "{\"age\":22,\"name\":\"张三\"}";
    
            Log.d(TAG, "fromJson:" + new Gson().fromJson(jsonStr, Person.class).toString());
    
            //来个复杂点的
    
            CompanyInfo companyInfo = new CompanyInfo();
            companyInfo.setCompanyName("公司名字");
            companyInfo.setCompanyOwner("老板");
    
            List<Person> personList = new ArrayList<>();
            personList.add(new Person("张三", 22));
            personList.add(new Person("李四", 23));
            personList.add(new Person("王五", 24));
            companyInfo.setPersonList(personList);
    
            String toJson = gson.toJson(companyInfo);
    
            Log.d(TAG, "toJson:" + toJson);
    
            Log.d(TAG, "fromJson:" + gson.fromJson(toJson, CompanyInfo.class));
        }
    
    
        public class Person {
            private String name;
            private int age;
    
            public Person() {
            }
    
            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;
            }
    
            @Override
            public String toString() {
                return "Person{" +
                        "name='" + name + '\'' +
                        ", age=" + age +
                        '}';
            }
        }
    
    
        public class CompanyInfo {
            private String companyName;
            private String companyOwner;
            private List<Person> personList;
    
            public String getCompanyName() {
                return companyName;
            }
    
            public void setCompanyName(String companyName) {
                this.companyName = companyName;
            }
    
            public String getCompanyOwner() {
                return companyOwner;
            }
    
            public void setCompanyOwner(String companyOwner) {
                this.companyOwner = companyOwner;
            }
    
            public List<Person> getPersonList() {
                return personList;
            }
    
            public void setPersonList(List<Person> personList) {
                this.personList = personList;
            }
    
            @Override
            public String toString() {
                return "CompanyInfo{" +
                        "companyName='" + companyName + '\'' +
                        ", companyOwner='" + companyOwner + '\'' +
                        ", personList=" + personList +
                        '}';
            }
        }
    
    }

# Gson处理空对象场景 #

//        UserInfo userInfo = new UserInfo();
    //        userInfo.setId(0);
    //        userInfo.setName("张三");
    //        userInfo.setAddress(null);
    
    //        {"id":0,"name":"张三"}
    
    
    //        UserInfo userInfo = new UserInfo();
    //        userInfo.setId(0);
    //        userInfo.setName("张三");
    //
    //        {"id":0,"name":"张三"}
    
    //        UserInfo userInfo = new UserInfo();
    //        userInfo.setId(0);
    //        userInfo.setName("张三");
    //        userInfo.setAddress("");
    //        
    //        {"address":"","id":0,"name":"张三"}
    
    
    
            UserInfo userInfo = new UserInfo();
            userInfo.setId(1);
            userInfo.setName("张三");
            userInfo.setAddress("地址");
            userInfo.setObject(new StudentInfo(2));
    
    //        {"address":"地址","data":{"studentId":2},"id":1,"name":"张三"}