<!-- autoconfigure-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
 
        <!-- 這個(gè)是用來(lái)提示用的-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
 
        <!-- fastjson-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.56</version>
        </dependency>
 
        <!-- gson-->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.2.4</version>
        </dependency>

public interface FormatProcessor {
    /**
     * 定義一個(gè)格式化的方法
     */
    <T> String format(T obj);
}

import com.google.gson.Gson;
 
public class GsonFormatProcessor implements FormatProcessor{
 
    @Override
    public <T> String format(T obj) {
        return "GsonFormatProcessor" + new Gson().toJson(obj);
    }
}

import com.alibaba.fastjson.JSON;
 
public class FastJsonFormatProcessor implements FormatProcessor{
 
    @Override
    public <T> String format(T obj) {
        return "FastJsonFormatProcessor:" + JSON.toJSONString(obj);
    }
}

import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
 
@Configuration
public class FormatAutoConfiguration {
 
    /**
     * @return
     * @ConditionalOnClass條件注解。如果 fastjson 類存在的情況下才加載對(duì)應(yīng)的實(shí)現(xiàn)類
     * 同一個(gè)接口，有幾種不同的實(shí)現(xiàn)類時(shí)，@Autowired 是按類型注入的，不知道要選哪一個(gè).
     * 按照第二點(diǎn)需求，用戶在沒選的情況下默認(rèn)選擇 fastjson，所以這里給 fastjson 的實(shí)現(xiàn)上打上 @Primary
     */
    @ConditionalOnClass(name = "com.alibaba.fastjson.JSON")
    @Bean
    @Primary
    public FormatProcessor fastJsonFormat() {
        return new FastJsonFormatProcessor();
    }
 
    /**
     * 如果 Gson 類存在的情況下才加載對(duì)應(yīng)的實(shí)現(xiàn)類
     *
     * @return
     */
    @ConditionalOnClass(name = "com.google.gson.Gson")
    @Bean
    public FormatProcessor gsonJsonFormat() {
        return new FastJsonFormatProcessor();
    }
}

import org.springframework.boot.context.properties.ConfigurationProperties;
 
@ConfigurationProperties(prefix = FormatProperties.ORMAT_PREFIX)
public class FormatProperties {
 
    public static final String ORMAT_PREFIX = "jackluo.format";
 
    private String type;
 
    public String getType() {
        return type;
    }
 
    public void setType(String type) {
        this.type = type;
    }
}

import com.jackluo.autoconfiguration.FormatProcessor;
 
public class FormatTemplate {
 
    private FormatProcessor formatProcessor;
 
    public FormatTemplate(FormatProcessor formatProcessor) {
        this.formatProcessor = formatProcessor;
    }
 
    public <T> String doFormat(T obj) {
        return formatProcessor.format(obj);
    }
 
}

import com.jackluo.format.FormatTemplate;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
 
@Import(FormatAutoConfiguration.class)
@EnableConfigurationProperties(FormatProperties.class)
@Configuration
public class JackluoFormatConfiguration {
 
    @Bean
    public FormatTemplate helloFormatTemplate(FormatProperties formatProperties, @Qualifier("fastJsonFormat") FormatProcessor formatProcessor) {
        if ("fastjson".equals(formatProperties.getType())) {
            return new FormatTemplate(new FastJsonFormatProcessor());
        }
        if ("gson".equals(formatProperties.getType())) {
            return new FormatTemplate(new GsonFormatProcessor());
        }
        return new FormatTemplate(formatProcessor);
    }
}

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.jackluo.autoconfiguration.JackluoFormatConfiguration

<dependency>
            <groupId>com.jackluo</groupId>
            <artifactId>jackformat-spring-boot-starter</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>