SpringBoot返回JSON

目录

• 1、SpringBoot返回JSON简介
• 2、整合jackson-databind
• 3、整合Gson
• 4、整合fastjson

1、SpringBoot返回JSON简介

随着web开发前后端分离技术的盛行，json是目前主流的前后端数据交互方式，使用json数据进行交互需要对json数据进行转换解析，需要用到一些json处理器，常用的json处理器有：

• jackson-databind，SpringBoot默认的json处理器
• Gson，是Google的一个开源框架
• fastjson，目前解析速度最快的开源解析框架，由阿里开发

下面分别介绍如何在SpringBoot中整合三大json解析框架。

2、整合jackson-databind

Jackson-databind是SpringBoot默认集成在web依赖中的框架，因此我们只需要引入spring-boot-starter-web依赖，就可以返回json数据：

接着上篇文章中的demo继续修改demo，先看下代码框架：

下面开始修改demo，返回json数据，首先在pojo下创建一个Good实体类，并且可以通过注解来解决日期格式等需求：

package com.gongsir.springboot02.pojo;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonIgnore;

import java.util.Date;

public class Good {
    private Integer id;
    private String name;
    @JsonIgnore
    private Double price;
    @JsonFormat(pattern = "yy-MM-dd")
    private Date dealDate;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

    public Date getDealDate() {
        return dealDate;
    }

    public void setDealDate(Date dealDate) {
        this.dealDate = dealDate;
    }
}

然后在controller包下创建一个GoodController，在方法上加上@ResponseBody注解（也可以直接使用@RestController注解整个类）即可返回json信息：

@Controller
@RequestMapping(value = "/good")
public class GoodController {

    @GetMapping(path = "/get")
    @ResponseBody
    public Good getGood(){
        Good good = new Good();
        good.setId(1);
        good.setName("MacBook Pro 2019");
        good.setPrice(16999.99);
        good.setDealDate(new Date());
        return good;
    }
}

此时可以使用浏览器或者postman工具来查看结果,运行项目，调用http://localhost:8080/good/get接口：

3、整合Gson

使用Gson需要将SpringBoot默认依赖的jackson-databind除去，然后引入Gson：

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <!--除去jackson-databind依赖-->
            <exclusions>
                <exclusion>
                    <groupId>com.fasterxml.jackson.core</groupId>
                    <artifactId>jackson-databind</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!--引入Gson依赖-->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
        </dependency>

创建一个gson配置：

package com.gongsir.springboot02.configuration;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.json.GsonHttpMessageConverter;

import java.lang.reflect.Modifier;

@Configuration
public class GsonConfig {
    @Bean
    GsonHttpMessageConverter gsonHttpMessageConverter(){
        GsonHttpMessageConverter gsonHttpMessageConverter = new GsonHttpMessageConverter();
        GsonBuilder builder = new GsonBuilder();
        //设置解析的日期格式
        builder.setDateFormat("yyyy-MM-dd");
        //设置忽略字段，忽略修饰符为protected的字段属性
        builder.excludeFieldsWithModifiers(Modifier.PROTECTED);
        Gson gson = builder.create();
        gsonHttpMessageConverter.setGson(gson);
        return gsonHttpMessageConverter;
    }
}

修改Good,java:

package com.gongsir.springboot02.pojo;

import java.util.Date;

public class Good {
    protected Integer id;
    private String name;
    private Double price;
    private Date dealDate;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

    public Date getDealDate() {
        return dealDate;
    }

    public void setDealDate(Date dealDate) {
        this.dealDate = dealDate;
    }
}

启动项目，再次访问http://localhost:8080/good/get接口：

4、整合fastjson

引入fastjson依赖，修改刚刚的pom.xml:

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <!--除去jackson-databind依赖-->
            <exclusions>
                <exclusion>
                    <groupId>com.fasterxml.jackson.core</groupId>
                    <artifactId>jackson-databind</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!--引入fastjson依赖-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>

配置fastjson有两种方法，方法一：自定义MyFastjsonConfig，提供FastJsonHttpMessageConverter Bean：

package com.gongsir.springboot02.configuration;

import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;

import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;

@Configuration
public class MyFastjsonConfig {
    @Bean
    FastJsonHttpMessageConverter fastJsonHttpMessageConverter(){
        FastJsonHttpMessageConverter converter = new FastJsonHttpMessageConverter();
        FastJsonConfig config = new FastJsonConfig();
        //升级之后的fastjson（1.2.28之后的版本）需要手动配置MediaType，否则会报错
        List<MediaType> supportedMediaTypes = new ArrayList<>();
        supportedMediaTypes.add(MediaType.APPLICATION_JSON);
        supportedMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);
        supportedMediaTypes.add(MediaType.APPLICATION_ATOM_XML);
        supportedMediaTypes.add(MediaType.APPLICATION_FORM_URLENCODED);
        supportedMediaTypes.add(MediaType.APPLICATION_OCTET_STREAM);
        supportedMediaTypes.add(MediaType.APPLICATION_PDF);
        supportedMediaTypes.add(MediaType.APPLICATION_RSS_XML);
        supportedMediaTypes.add(MediaType.APPLICATION_XHTML_XML);
        supportedMediaTypes.add(MediaType.APPLICATION_XML);
        supportedMediaTypes.add(MediaType.IMAGE_GIF);
        supportedMediaTypes.add(MediaType.IMAGE_JPEG);
        supportedMediaTypes.add(MediaType.IMAGE_PNG);
        supportedMediaTypes.add(MediaType.TEXT_EVENT_STREAM);
        supportedMediaTypes.add(MediaType.TEXT_HTML);
        supportedMediaTypes.add(MediaType.TEXT_MARKDOWN);
        supportedMediaTypes.add(MediaType.TEXT_PLAIN);
        supportedMediaTypes.add(MediaType.TEXT_XML);
        converter.setSupportedMediaTypes(supportedMediaTypes);

        config.setDateFormat("yyyy-MM-dd");
        config.setCharset(Charset.forName("UTF-8"));
        config.setSerializerFeatures(
                //json格式化
                SerializerFeature.PrettyFormat,
                //输出value为null的数据
                SerializerFeature.WriteMapNullValue
        );
        converter.setFastJsonConfig(config);
        return converter;
    }
}

方法二：实现WebMvcConfigurer接口,重写configureMessageConverters方法：

package com.gongsir.springboot02.configuration;

import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;

@Configuration
public class FastJsonConfig implements WebMvcConfigurer {
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        FastJsonHttpMessageConverter converter = new FastJsonHttpMessageConverter();
        com.alibaba.fastjson.support.config.FastJsonConfig config = new com.alibaba.fastjson.support.config.FastJsonConfig();
        //升级之后的fastjson（1.2.28之后的版本）需要手动配置MediaType，否则会报错
        List<MediaType> supportedMediaTypes = new ArrayList<>();
        supportedMediaTypes.add(MediaType.APPLICATION_JSON);
        supportedMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);
        supportedMediaTypes.add(MediaType.APPLICATION_ATOM_XML);
        supportedMediaTypes.add(MediaType.APPLICATION_FORM_URLENCODED);
        supportedMediaTypes.add(MediaType.APPLICATION_OCTET_STREAM);
        supportedMediaTypes.add(MediaType.APPLICATION_PDF);
        supportedMediaTypes.add(MediaType.APPLICATION_RSS_XML);
        supportedMediaTypes.add(MediaType.APPLICATION_XHTML_XML);
        supportedMediaTypes.add(MediaType.APPLICATION_XML);
        supportedMediaTypes.add(MediaType.IMAGE_GIF);
        supportedMediaTypes.add(MediaType.IMAGE_JPEG);
        supportedMediaTypes.add(MediaType.IMAGE_PNG);
        supportedMediaTypes.add(MediaType.TEXT_EVENT_STREAM);
        supportedMediaTypes.add(MediaType.TEXT_HTML);
        supportedMediaTypes.add(MediaType.TEXT_MARKDOWN);
        supportedMediaTypes.add(MediaType.TEXT_PLAIN);
        supportedMediaTypes.add(MediaType.TEXT_XML);
        converter.setSupportedMediaTypes(supportedMediaTypes);

        config.setDateFormat("yyyy-MM-dd");
        config.setCharset(Charset.forName("UTF-8"));
        config.setSerializerFeatures(
                //json格式化
                SerializerFeature.PrettyFormat,
                //输出value为null的数据
                SerializerFeature.WriteMapNullValue
        );
        converter.setFastJsonConfig(config);
        //将converter加入到converters
        converters.add(converter);
    }
}

启动项目，再次调用接口：