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Springboot中Jackson用法详解

2025年01月03日 • Java •我要评论
前言springboot自带默认json解析jackson，可以在不引入其他json解析包情况下，解析json字段jackson用法本文使用的是jdk23和springboot3.4.x版本，如果是在

前言

springboot自带默认json解析jackson，可以在不引入其他json解析包情况下，解析json字段

jackson用法

本文使用的是jdk23和springboot3.4.x版本，如果是在非springboot项目，就动态添加包

<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
    <groupid>com.fasterxml.jackson.core</groupid>
    <artifactid>jackson-databind</artifactid>
    <version>2.18.2</version>
</dependency>

将对象解析为json字符串

import com.fasterxml.jackson.databind.objectmapper;
import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

import java.io.ioexception;

@data
@builder
@noargsconstructor
@allargsconstructor
public class user {

    private long id;

    private string name;

    public static void main(string[] args) {
        user user = new user(1l, "aa");
        objectmapper objectmapper = new objectmapper();
        try {
            string json = objectmapper.writevalueasstring(user);
            system.out.println(json);
        } catch (ioexception e) {
            throw new runtimeexception(e);
        }
    }
}

输出结果为

将json解析为对象

import com.fasterxml.jackson.databind.objectmapper;
import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

import java.io.ioexception;

@data
@builder
@noargsconstructor
@allargsconstructor
public class user {

    private long id;

    private string name;

    public static void main(string[] args) {
        user user = new user(1l, "aa");
        objectmapper objectmapper = new objectmapper();
        try {
            string json = objectmapper.writevalueasstring(user);
            system.out.println(json);
            user user1 = objectmapper.readvalue(json, user.class);
            system.out.println(user1);
        } catch (ioexception e) {
            throw new runtimeexception(e);
        }
    }
}

将json文件转换为json

将user.json放置于resources文件夹下

import com.fasterxml.jackson.databind.objectmapper;
import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

import java.io.file;
import java.io.ioexception;
import java.util.objects;

@data
@builder
@noargsconstructor
@allargsconstructor
public class user {

    private long id;

    private string name;

    public static void main(string[] args) {
        user user = new user(1l, "aa");
        objectmapper objectmapper = new objectmapper();
        try {
            string json = objectmapper.writevalueasstring(user);
            system.out.println(json);
            file file = new file(objects.requirenonnull(user.class.getclassloader().getresource("user.json")).getfile());

            user user1 = objectmapper.readvalue(file, user.class);
            system.out.println(user1);
        } catch (ioexception e) {
            throw new runtimeexception(e);
        }
    }
}

输出结果为

将url转换成json

import com.fasterxml.jackson.databind.objectmapper;
import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

import java.io.ioexception;
import java.net.uri;
import java.net.url;

@data
@builder
@noargsconstructor
@allargsconstructor
public class user {

    private long id;

    private string name;

    public static void main(string[] args) {
        user user = new user(1l, "aa");
        objectmapper objectmapper = new objectmapper();
        try {
            string json = objectmapper.writevalueasstring(user);
            system.out.println(json);
            url url = uri.create("http://192.168.69.183:16023/user.json").tourl();

            user user2 = objectmapper.readvalue(url, user.class);
            system.out.println(user2);
        } catch (ioexception e) {
            throw new runtimeexception(e);
        }
    }
}

备注: 搭建个nginx服务器环境，将user.json放入静态资源映射下

jdk20版本以下的url需要这么写

url url = new url("http://192.168.69.183:16023/user.json");

这种jdk20以上过期了，转换成

url url = uri.create("http://192.168.69.183:16023/user.json").tourl();

字节转换成json

import com.fasterxml.jackson.databind.objectmapper;
import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

import java.io.ioexception;
import java.nio.charset.standardcharsets;

@data
@builder
@noargsconstructor
@allargsconstructor
public class user {

    private long id;

    private string name;

    public static void main(string[] args) {

        objectmapper objectmapper= new objectmapper();
       string json = """
               {"id":1,"name":"aa"}
               """;
        try {

            user user2 = objectmapper.readvalue(json.getbytes(standardcharsets.utf_8), user.class);
            system.out.println(user2);
        } catch (ioexception e) {
            throw new runtimeexception(e);
        }
    }
}

输出结果为

jdk17版本以下字符串需要这些写

string json = "{\"id\":1,\"name\":\"aa\"}";

字符串转义

json数组转对象数组

package cn.com.ut.cloud.demoobjectmapepr.model;

import com.fasterxml.jackson.core.type.typereference;
import com.fasterxml.jackson.databind.objectmapper;
import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

import java.io.ioexception;
import java.util.list;

@data
@builder
@noargsconstructor
@allargsconstructor
public class user {

    private long id;

    private string name;

    public static void main(string[] args) {

        objectmapper objectmapper = new objectmapper();
        list<user> userlist = list.of(new user(1l, "aa"),
                new user(2l, "bb"));
        try {
            string json = objectmapper.writevalueasstring(userlist);
            system.out.println(json);
            list<user> list = objectmapper.readvalue(json, new typereference<>() {
            });
            system.out.println(list);
        } catch (ioexception e) {
            throw new runtimeexception(e);
        }
    }
}

输出结果为

image.png

json转map

import com.fasterxml.jackson.core.type.typereference;
import com.fasterxml.jackson.databind.objectmapper;
import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

import java.io.ioexception;
import java.util.map;

@data
@builder
@noargsconstructor
@allargsconstructor
public class user {

    private long id;

    private string name;

    public static void main(string[] args) {

        objectmapper objectmapper = new objectmapper();
        user user = new user(1l, "aa");
        try {
            string json = objectmapper.writevalueasstring(user);
            system.out.println(json);
            map<string, object> map = objectmapper.readvalue(json,
                    new typereference<>() {
                    });
            system.out.println(map);
        } catch (ioexception e) {
            throw new runtimeexception(e);
        }
    }
}

输出结果为

jsonnode使用

jsonnode可以将json中的字段取出来

import com.fasterxml.jackson.databind.jsonnode;
import com.fasterxml.jackson.databind.objectmapper;
import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

import java.io.ioexception;

@data
@builder
@noargsconstructor
@allargsconstructor
public class user {

    private long id;

    private string name;

    public static void main(string[] args) {

        objectmapper objectmapper = new objectmapper();
        user user = new user(1l, "aa");
        try {
            string json = objectmapper.writevalueasstring(user);
            system.out.println(json);
            jsonnode jsonnode = objectmapper.readtree(json);

            system.out.println(jsonnode.get("id").astext());
        } catch (ioexception e) {
            throw new runtimeexception(e);
        }
    }
}

输出结果为

string id = jsonnode.get("id").astext(); 
double id = jsonnode.get("id").asdouble();
int id = jsonnode.get("id").asint(); 
long id = jsonnode.get("id").aslong();

动态添加json字段

import com.fasterxml.jackson.databind.objectmapper;
import com.fasterxml.jackson.databind.node.objectnode;
import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

@data
@builder
@noargsconstructor
@allargsconstructor
public class user {

    private long id;

    private string name;

    public static void main(string[] args) {

        objectmapper objectmapper = new objectmapper();

        objectnode objectnode = objectmapper.createobjectnode();
        objectnode.put("id", "1");
        objectnode.put("name", "1");
        objectnode.put("age", "1");
        system.out.println(objectnode.tostring());
    }
}

输出结果为

总结

可以使用springboot自身携带的jackson包操作json,当然，现在还有很多优秀的json解析包，根据自身擅长的做技术选型

以上就是springboot中jackson用法详解的详细内容，更多关于springboot jackson用法的资料请关注代码网其它相关文章！

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