SpringBoot返回JSON

2019 年 10 月 11 日
笔记

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：