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文章目录
  1. 1. Http编码配置
  2. 2. MyAutoConfig配置

Spring Boot封装好的自动配置很简单，在用得很轻松的同时，有没有想过，我们自己的项目中也根据自己的需求写一个具备Spring Boot自动配置功能的冲动呢？首先，来说说Http编码配置的例子，然后参考这个例子，我们自己来实现一个自动配置的功能。

Http编码配置

  • 添加配置，即在 application.properties 上添加：

    #HTTP encoding (HttpEncodingProperties)
spring.http.encoding.charset=UTF-8  # the encoding of HTTP request/response
spring.http.encoding.enabled=true #enabled http encoding support
spring.http.encoding.force=true #force the configured encoding

当然，不一定要”application.properties”这样的文件名，我们可以新建一个”application-myauto.properties”文件，只需要在 @ConfigurationProperties 的属性 locations 里指定properties的位置即可，且需要在入口类上配置。下面举个例子：

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
@Component
@ConfigurationProperties(prefix = "spring.http.encoding",locations = {"classpath:config/application-myauto.properties"}) //1
public class MyAutoSettings {
    private String name;
    private Long age;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Long getAge() {
        return age;
    }
    public void setAge(Long age) {
        this.age = age;
    }
}

  • Spring Boot实现HttpEncoding自动配置的源码如下：

    import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "spring.http.encoding")//在 application.properties 配置的时候前缀是 spring.http.encoding
public class HttpEncodingProperties {
    public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");//默认编码方式为UTF-8,若修改可使用 spring.http.encoding.charset=编码
    private Charset charset = DEFAULT_CHARSET;
    private boolean force = true;//设置 forceEncoding,默认为true，若修改可使用 spring.http.encoding.force=false

    public Charset getCharset() {    
        return this.charset;
    }
    public void setCharset(Charset charset) {
        this.charset = charset;
    }
    ....
}

  • 配置Bean，根据条件配置CharsetEncodingFilter的Bean

    @Configuration
@EnableConfigurationProperties(HttpEncodingProperties.class)//开启属性注入，通过@EnableConfigurationProperties 声明，使用 @Autowired注入
@ConditionalOnClass(CharacterEncodingFilter.class)//当CharacterEncodingFilter在类路径的条件下
@ConditionalOnProperties(prefix = "spring.http.encoding",value = "enabled",matchIfMissing = true)//当设置 spring.http.encoding = enabled 的情况下，如果没有设置则默认为true,即条件符合；
public class HttpEncodingAutoConfiguration {

    @Autowired
    private HttpEncodingProperties httpEncodingProperties;

    @Bean // 像使用Java 配置的方式配置CharacterEncodingFilter 这个Bean
    @ConditionalOnMissingBean(CharacterEncodingFilter.class)//当容器中没有这个Bean的时候新建Bean
    public CharacterEncodingFilter characterEncodingFilter() {
        CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
        filter.setEncoding(this.httpEncodingProperties.getCharset().name());
        filter.setForceEncoding(this.httpEncodingProperties.isForce());
        return filter;
    }
}

MyAutoConfig配置

下面就来创建一个我们自己项目的自动配置。

  • 依赖

    <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-autoconfigure</artifactId>
    <version>1.3.5.RELEASE</version>
</dependency>

  • 属性配置

    1.application.properties中填入：

    app.name=jmust
app.source=wx

    2.配置类

    @ConfigurationProperties(prefix="app")
public class MyAutoPrpperties {
    private static final String NAME = "jmust";
    private String name = NAME;

    public String getName() {
        return name;
    }

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

    在 application.properties 中通过 app.name= 来设置，默认为 app.name = jmust

  • 判断依据

/**
 * Created by LK on 2016/6/26.
 */
public class MyAutoService {
    private String name;

    public String sayName(){
        return "zzz"+ name;
    }

    public String getName() {
        return name;
    }

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

  • 自动配置

    import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * Created by LK on 2016/6/26.
 */

@Configuration
@EnableConfigurationProperties(MyAutoProperties.class)
@ConditionalOnClass(MyAutoService.class)
@ConditionalOnProperty(prefix="app",value = "enabled",matchIfMissing = true)
public class MyAutoServiceAutoConfiguration {

    @Autowired
    private MyAutoProperties myAutoProperties;

    @Bean
    @ConditionalOnMissingBean(MyAutoService.class)
    public MyAutoService myAutoService(){
        MyAutoService myAutoService = new MyAutoService();
        myAutoService.setName(myAutoProperties.getName());
        return myAutoService;
    }
}

  • 注册配置

如果想自动配置生效，需要注册自动配置类。在src/main/resources 下新建META-INF/spring.factories,在spring.factories中填如下内容注册：

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.jmust.service.demo.MyAutoServiceAutoConfiguration

  • 使用 

    import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Created by LK on 2016/6/26.
 */
@RestController
@SpringBootApplication
public class DemoApplication {

    @Autowired
    private MyAutoService myAutoService;

    @RequestMapping("/")
    public String index(){
        return myAutoService.sayName();
    }

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

    在项目中可以直接注入MyAutoService的Bean,但是项目中我们并没有配置这个 Bean,这就是通过自动配置完成的。

  • 效果

    访问 http://localhost:8080,就会出现你在application.properties中对应name的内容了。

文章目录
  1. 1. Http编码配置
  2. 2. MyAutoConfig配置