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spring boot 的conditioanal的解析

发布时间:2020-08-11 08:38:26 来源:网络 阅读:727 作者:zcp617504296 栏目:软件技术

一:


package com.zcp.springstart2;


import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.context.ConfigurableApplicationContext;


@SpringBootApplication

public class App {


public static void main(String[] args) {

ConfigurableApplicationContext context = SpringApplication.run(App.class, args);

System.out.println(System.getProperty("file.encoding"));

System.out.println(context.getBeansOfType(EncodingConvert.class));

System.out.println(">>>>>>>>>>>>>start>>>>>>>>>>>>");

System.out.println(context.getBeansOfType(Runnable.class));

System.out.println(">>>>>>>>>>>>>end>>>>>>>>>>>>");

context.close();

}


}


接口:

package com.zcp.springstart2;


public interface EncodingConvert {


}


接口的实现:

package com.zcp.springstart2;


public class UTF8EncodingConvert implements EncodingConvert {


}


package com.zcp.springstart2;


public class GBKEncodingConvert implements EncodingConvert {


}


package com.zcp.springstart2;


import org.springframework.context.annotation.Condition;

import org.springframework.context.annotation.ConditionContext;

import org.springframework.core.type.AnnotatedTypeMetadata;


public class GBKCondition implements Condition {


@Override

public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {

String encoding = System.getProperty("file.encoding");

if(null != encoding){

return "gbk".equals(encoding.toLowerCase());

}

return false;

}


}



package com.zcp.springstart2;


import org.springframework.context.annotation.Condition;

import org.springframework.context.annotation.ConditionContext;

import org.springframework.core.type.AnnotatedTypeMetadata;


public class UTF8Condition implements Condition {


@Override

public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {

String encoding  = System.getProperty("file.encoding");

if(null != encoding){

return "utf-8".equals(encoding.toLowerCase());

}

return false;

}


}



常用的conditional的使用:

package com.zcp.springstart2;


import org.springframework.boot.SpringBootConfiguration;

import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;

import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;

import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;

import org.springframework.context.annotation.Bean;


@SpringBootConfiguration

public class UserConfig {

@Bean

@ConditionalOnProperty(name="runnable.enabled",havingValue="true",matchIfMissing=true)

public Runnable createRunnable(){

return new Runnable() {

@Override

public void run() {

System.out.println("UserConfig中的Runnable");

}

};

}

@Bean

@ConditionalOnClass(name="com.zcp.springstart2.User")

public Runnable createRunnableOnClass(){

return new Runnable() {

@Override

public void run() {

System.out.println("UserConfig中的createRunnableOnBean");

}

};

}


@Bean

@ConditionalOnBean(name="user")

public Runnable createRunnableOnBean(){

return new Runnable() {

@Override

public void run() {

System.out.println("UserConfig中的createRunnableOnBean");

}

};

}

}


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