SpringBoot返回JSON

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一、SpringBoot返回JSON簡介

隨着web開發先後端分離技術的盛行，json是目前主流的先後端數據交互方式，使用json數據進行交互須要對json數據進行轉換解析，須要用到一些json處理器，經常使用的json處理器有：java

• jackson-databind，SpringBoot默認的json處理器
• Gson，是Google的一個開源框架
• fastjson，目前解析速度最快的開源解析框架，由阿里開發

下面分別介紹如何在SpringBoot中整合三大json解析框架。web

二、整合jackson-databind

Jackson-databind是SpringBoot默認集成在web依賴中的框架，所以咱們只須要引入spring-boot-starter-web依賴，就能夠返回json數據：spring

接着上篇文章中的demo繼續修改demo，先看下代碼框架：json

下面開始修改demo，返回json數據，首先在pojo下建立一個Good實體類，而且能夠經過註解來解決日期格式等需求：後端

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;
    }
}

而後在controller包下建立一個GoodController，在方法上加上@ResponseBody註解（也能夠直接使用@RestController註解整個類）便可返回json信息：瀏覽器

@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;
    }
}

此時可使用瀏覽器或者postman工具來查看結果,運行項目，調用http://localhost:8080/good/get接口：springboot

三、整合Gson

使用Gson須要將SpringBoot默認依賴的jackson-databind除去，而後引入Gson：app

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

建立一個gson配置：框架

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();
        //設置解析的日期格式
        builder.setDateFormat("yyyy-MM-dd");
        //設置忽略字段，忽略修飾符爲protected的字段屬性
        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;
    }
}

啓動項目，再次訪問http://localhost:8080/good/get接口：

四、整合fastjson

引入fastjson依賴，修改剛剛的pom.xml:

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

配置fastjson有兩種方法，方法一：自定義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();
        //升級以後的fastjson（1.2.28以後的版本）須要手動配置MediaType，不然會報錯
        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,
                //輸出value爲null的數據
                SerializerFeature.WriteMapNullValue
        );
        converter.setFastJsonConfig(config);
        return converter;
    }
}

方法二：實現WebMvcConfigurer接口,重寫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();
        //升級以後的fastjson（1.2.28以後的版本）須要手動配置MediaType，不然會報錯
        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,
                //輸出value爲null的數據
                SerializerFeature.WriteMapNullValue
        );
        converter.setFastJsonConfig(config);
        //將converter加入到converters
        converters.add(converter);
    }
}

啓動項目，再次調用接口：

原文出處：https://www.cnblogs.com/gongsir/p/11654013.html