本篇概览

• 本文是《jackson学习》系列的终篇，经过前面的一系列实战，相信您已可以熟练使用jackson灵活的执行各种json序列化和反序列化操作，那么，本篇就以轻松的方式来完成整个系列吧；
• 上一篇介绍的是在springboot中通过配置文件对jackson做设置，今天要聊的是另一种常用的jackson配置方式：配置类，就是自己编写代码实例化和配置springboot全局使用的ObjectMapper实例；

源码下载

1. 如果您不想编码，可以在GitHub下载所有源码，地址和链接信息如下表所示(https://github.com/zq2599/blog_demos)：

2. 这个git项目中有多个文件夹，本章的应用在jacksondemo文件夹下，如下图红框所示：

3. jacksondemo是父子结构的工程，本篇的代码在springbootconfigbean子工程中，如下图：

编码

1. 在父工程jacksondemo下新增子工程springbootconfigbean，pom.xml如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <artifactId>jacksondemo</artifactId>
        <groupId>com.bolingcavalry</groupId>
        <version>1.0-SNAPSHOT</version>
        <relativePath>../pom.xml</relativePath>
    </parent>
    <groupId>com.bolingcavalry</groupId>
    <artifactId>springbootconfigbean</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springbootconfigbean</name>
    <description>Demo project for Spring Boot with Jackson, configuration from config bean</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <!--不用spring-boot-starter-parent作为parent时的配置-->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.3.3.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <!-- swagger依赖 -->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
        </dependency>
        <!-- swagger-ui -->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2. 本文最重要的代码是配置类JacksonConfig.java，如下，需要ConditionalOnMissingBean注解避免冲突，另外还给实例指定了名称customizeObjectMapper，如果应用中通过Autowired使用此实例，需要指定这个名字，避免报错"There is more than one bean of 'ObjectMapper ' type"：

@Configuration
public class JacksonConfig {

    @Bean("customizeObjectMapper")
    @Primary
    @ConditionalOnMissingBean(ObjectMapper.class)
    public ObjectMapper getObjectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper mapper = builder.build();

        // 日期格式
        mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd hh:mm:ss"));

        // 美化输出
        mapper.enable(SerializationFeature.INDENT_OUTPUT);

        return mapper;
    }
}

3. 对于JacksonConfig.getObjectMapper方法内的设置，如果您想做更多设置，请参考《jackson学习之三：常用API操作》里面的设置内容；

• 启动类依然很简单：

package com.bolingcavalry.springbootconfigbean;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringbootConfigBeanApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootConfigBeanApplication.class, args);
    }

}

4. swagger配置：

package com.bolingcavalry.springbootconfigbean;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.service.Contact;
import springfox.documentation.service.Tag;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;

@Configuration
@EnableSwagger2
public class SwaggerConfig {

    @Bean
    public Docket createRestApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(apiInfo())
                .tags(new Tag("JsonPropertySerializationController", "JsonProperty相关测试"))
                .select()
                // 当前包路径
                .apis(RequestHandlerSelectors.basePackage("com.bolingcavalry.springbootconfigbean.controller"))
                .paths(PathSelectors.any())
                .build();
    }

    //构建 api文档的详细信息函数,注意这里的注解引用的是哪个
    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                //页面标题
                .title("SpringBoot整合Jackson(基于配置文件)")
                //创建人
                .contact(new Contact("程序员欣宸", "https://github.com/zq2599/blog_demos", "zq2599@gmail.com"))
                //版本号
                .version("1.0")
                //描述
                .description("API 描述")
                .build();
    }
}

5. 最后是测试用的Controller类，要注意的是在使用ObjectMapper实例的地方，用Autowired注解的时候，记得带上Qualifier注解：

package com.bolingcavalry.springbootconfigbean.controller;

import com.bolingcavalry.springbootconfigbean.bean.Test;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/jsonproperty")
@Api(tags = {"JsonPropertySerializationController"})
public class JsonPropertySerializationController {

    private static final Logger logger = LoggerFactory.getLogger(JsonPropertySerializationController.class);

    @Qualifier("customizeObjectMapper")
    @Autowired
    ObjectMapper mapper;

    @ApiOperation(value = "测试序列化", notes = "测试序列化")
    @RequestMapping(value = "/serialization", method = RequestMethod.GET)
    public Test serialization() throws JsonProcessingException {

        Test test = new Test();
        logger.info(mapper.writeValueAsString(test));

        return test;
    }

    @ApiOperation(value = "测试反序列化", notes="测试反序列化")
    @RequestMapping(value = "/deserialization",method = RequestMethod.PUT)
    public String deserialization(@RequestBody Test test) {
        return test.toString();
    }
}

验证

1. 启动SpringbootConfigBeanApplication后，浏览器打开：http://localhost:8080/swagger-ui.html
2. 先验证序列化接口/jsonproperty/serialization：

3. 再验证反序列化接口 /jsonproperty/deserialization：

• 至此，整个《jackson学习》系列就全部完成了，希望这十篇内容能够给您带来一些参考，助您在编码过程中更加得心应手的使用Jackson；