Maven项目

一、maven相关设置

1、下载apache-maven-3.6.1，

2、解压repo放入到maven中

3、在apache-maven-3.6.1/conf替换settings，然后设置为自己的镜像仓库

二、创建maven项目

1、点击File->New->Project

2、选择Maven中的安装的jdk，后一直下一步

 3、然后点击File->Settings-Maven, 设置Maven home path、User settings file、Local respository

 4、为了避免每次新建项目需要重复设置的问题，可以File->New Projects Setup->setttings for New Projects

二、Java对象、jsonStr、Map、json转换

package com.lemon.json;

public class User {
    //json转java对象，java对象必须有私有属性，对应的get/set方法，空参。
    //属性的名称必须和json的key保持一致
    private String username;
    private String password;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "username='" + username + '/'' +
                ", password='" + password + '/'' +
                '}';
    }
}

package com.lemon.json;
public class Student {
    private String name;
    private int 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 "Student{" +
                "name='" + name + '/'' +
                ", age=" + age +
                '}';
    }
}

package com.lemon.json;

import com.alibaba.fastjson.JSONObject;

import java.util.List;
import java.util.Map;


public class JsonDemo {
    public static void main(String[] args) {
        //1、 parseObject(json字符串，需要转成的java类.class)  jsonStr =>java对象
        String jsonStr = "{/"username/": /"ZHANGSAN/", /"password/": /"123456/"}";
        User user = JSONObject.parseObject(jsonStr, User.class);
        System.out.println(user);
        System.out.println(user.getUsername());
        System.out.println(user.getPassword());
        System.out.println("===============1、jsonStr =>java对象===========");

        //2、java对象=>jsonStr
        String s = JSONObject.toJSONString(user);
        System.out.println(s);
        System.out.println("===============2、java对象=>jsonStr===========");


        //3、 Map 天生就能和json互转

        Map<String, Object> map = JSONObject.parseObject(jsonStr, Map.class);
        System.out.println(map.get("username"));
        String s1 = JSONObject.toJSONString(map);
        System.out.println(s1);
        System.out.println("=============== 3、 Map 天生就能和json互转===========");


        //4、json数组 =>java对象
        String jsonStr2 = "[{/"name/": /"张三/", /"age/": 18},{/"name/": /"李四/", /"age/": 16}]";
        List<Student> students = JSONObject.parseArray(jsonStr2, Student.class);
        System.out.println(students);
        System.out.println("=============== 4、json数组 =>java对象===========");

    }
}