Google开源GSON的使用

* 谷歌开原项目GitHub地址：https://github.com/google/gson

1.新建一个maven项目，引入gson的dependency坐标依赖以及commons-io的坐标：

        <!--处理json格式数据-->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.4</version>
        </dependency>
 
        <!--做io文件的操作-->
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.4</version>
        </dependency>

2.编写一个Student 的JavaBean：

package com.wxd.basic.gson;
 
import java.util.Arrays;
 
public class Student {
    private String name;
    private Integer age;
    private String birthday;
    private String[] major;
    private boolean has_girl_friend;
    private String car;
    private String house;
    private String comment;
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public Integer getAge() {
        return age;
    }
 
    public void setAge(Integer age) {
        this.age = age;
    }
 
    public String getBirthday() {
        return birthday;
    }
 
    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }
 
    public String[] getMajor() {
        return major;
    }
 
    public void setMajor(String[] major) {
        this.major = major;
    }
 
    public boolean isHas_girl_friend() {
        return has_girl_friend;
    }
 
    public void setHas_girl_friend(boolean has_girl_friend) {
        this.has_girl_friend = has_girl_friend;
    }
 
    public String getCar() {
        return car;
    }
 
    public void setCar(String car) {
        this.car = car;
    }
 
    public String getHouse() {
        return house;
    }
 
    public void setHouse(String house) {
        this.house = house;
    }
 
    public String getComment() {
        return comment;
    }
 
    public void setComment(String comment) {
        this.comment = comment;
    }
 
    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", birthday='" + birthday + '\'' +
                ", major=" + Arrays.toString(major) +
                ", has_girl_friend=" + has_girl_friend +
                ", car='" + car + '\'' +
                ", house='" + house + '\'' +
                ", comment='" + comment + '\'' +
                '}';
    }
}

3.编写GsonSample解析类

package com.wxd.basic.gson;
 
import com.google.gson.FieldNamingStrategy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
 
import java.lang.reflect.Field;
 
public class GsonSample {
    public static void main(String[] args){
        Student s=new Student();
        s.setName("张三");
        s.setAge(23);
        s.setBirthday("1995-06-30");
        s.setMajor(new String[]{"打球","看书"});
        s.setHas_girl_friend(false);
        s.setCar(null);
        s.setHouse(null);
        s.setComment("这是一个注释！");
 
        GsonBuilder gsonBuilder=new GsonBuilder();
        //gsonBuilder.setDateFormat("yyyy-MM-dd").create();日期格式转换
        gsonBuilder.setPrettyPrinting();//这样设置后通过GsonBuilder构建的Gson对象打印出来是美化过的json格式数据
        gsonBuilder.setFieldNamingStrategy(new FieldNamingStrategy() {
            @Override
            public String translateName(Field field) {
                if(field.getName().equals("name")){
                    return "NAME";//修改了name属性
                }
                return field.getName();
            }
        });
        Gson gson=gsonBuilder.create();
//      Gson gson=new Gson();
        System.out.println(gson.toJson(s));
    }
}

4.控制台输出

①通过new Gson()的方式构建后的打印输出：
{"name":"张三","age":23,"birthday":"1995-06-30","major":["打球","看书"],"has_girl_friend":false,"comment":"这是一个注释！"}
②通过GsonBuilder的方式构建Gson对象后输出：

{
　　"NAME": "张三",
　　"age": 23,
　　"birthday": "1995-06-30",
　　"major": [
　  　　"打球",
　　　　"看书"
　　],
　　"has_girl_friend": false,
　　"comment": "这是一个注释！"
　　}

5.使用Gson解析json格式数据：

package com.wxd.basic.gson;
 
import com.google.gson.Gson;
import org.apache.commons.io.FileUtils;
 
import java.io.File;
import java.io.IOException;
 
public class GsonReadSample {
    public static void main(String[] args){
        File file=new File(GsonReadSample.class.getResource("/Student.json").getFile());
        try {
            String content = FileUtils.readFileToString(file);//如果不知道怎么读文件可以自己手动写个json字符串如下(把这行注释掉，下面的放开就行)：
//            String content="{\n" +
//                    "  \"NAME\": \"张三\",\n" +
//                    "  \"age\": 23,\n" +
//                    "  \"birthday\": \"1995-06-30\",\n" +
//                    "  \"major\": [\n" +
//                    "    \"打球\",\n" +
//                    "    \"看书\"\n" +
//                    "  ],\n" +
//                    "  \"has_girl_friend\": false,\n" +
//                    "  \"comment\": \"这是一个注释！\"\n" +
//                    "}";
            Gson gson=new Gson();
            Student student = gson.fromJson(content, Student.class);
            System.out.println(student);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

6.控制台输出:

Student{name='null', age=23, birthday='1995-06-30', major=[打球, 看书], has_girl_friend=false, car='null', house='null', comment='这是一个注释！'}