Question

我希望能够自动装配单个bean（foo）

@Component
public class FooUser {

  @Autowire Foo foo;
}

由另一个单身人士的方法（FooFactory.createFoo）

创建

@Service
public class FooFactory {

  public Foo createFoo() {...}
}

使用xml只需factory-method。我怎么能用注释来做呢？

Answer 1

尝试使用Java @Configuration：

@Configuration 
public class Config {

    @Bean
    public FooUser fooUser() {
        return new FooUser(foo());
    }

    @Bean
    public FooFactory fooFactory() {
        return new FooFactory();
    }

    @Bean
    public Foo foo() {
        return fooFactory().createFoo();
    }

}

Answer 2

您需要java-config - the @Bean annotation。

将您的班级定义为@Configuration，将您的方法定义为@Bean

Answer 3

Spring Components也可以定义工厂方法。来自documentation：

的剪辑

@Component
public class FactoryMethodComponent {

  @Bean @Qualifier("public")
  public TestBean publicInstance() {
      return new TestBean("publicInstance");
  }

  public void doWork() {
      // Component method implementation omitted
  }
}

Answer 4

使用FactoryBean Spring接口。那么你将能够自动使用T

编辑： BeanFactory是Spring中的一个接口，如果你实现它，你可以创建一个对象的工厂，如：

public class FooFactoryBean implements FactoryBean<Foo>{
   .................. 
   }

然后你可以初始化bean：

@Bean
public FooFactoryBean foo(){ 
      return new FooFactoryBean(); 
    }

然后如果你自动装配Foo它Spring会理解FooFactoryBean是所需的工厂

   @Autowired
       Foo foo;

Answer 5

Spring Boot：工厂方法

import java.util.HashMap;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

enum ParsersConst {
    bofa, jpm, wellsforgo
}

interface Parser {
    String readFromFile(String file);
}

class JPM implements Parser {
    @Override
    public String readFromFile(String file) {
        System.out.println("From JPM Parser");
        //LOGIC to read file data
        return "JPM";
    }
}

class Bofa implements Parser {
    @Override
    public String readFromFile(String file) {
        System.out.println("From Bofa Parser");
        //LOGIC to read file data
        return "BOFA";
    }
}

class WellsForgo implements Parser {
    @Override
    public String readFromFile(String file) {
        System.out.println("From Wellsforgo Parser"); 
        //LOGIC to read file data
        return "WellsForgo";
    }
}

class ParserCreator {
    private Map<ParsersConst, Parser> parserMap;

    public Parser createParser(ParsersConst parsConst) {
        Parser parser = parserMap.get(parsConst);
        if (parserMap.get(parsConst) != null) {
            return parser;
        }
        throw new IllegalArgumentException("Unknown Parser");
    }

    public void setParserMap(Map<ParsersConst, Parser> parserMap) {
        this.parserMap = parserMap;
    }
}

@Configuration
class ParserConfig {

    @Bean
    public ParserCreator parserCreatorFactory() {
        ParserCreator factory = new ParserCreator();
        Map<ParsersConst, Parser> map = new HashMap<ParsersConst, Parser>();
        map.put(ParsersConst.bofa, new Bofa());
        map.put(ParsersConst.wellsforgo, new WellsForgo());
        map.put(ParsersConst.jpm, new JPM());
        factory.setParserMap(map);
        return factory;

    }

    @Bean
    public Parser bofa() {
        return parserCreatorFactory().createParser(ParsersConst.bofa);
    }

    @Bean
    public Parser wellsforgo() {
        return parserCreatorFactory().createParser(ParsersConst.wellsforgo);
    }

    @Bean
    public Parser jpm() {
        return parserCreatorFactory().createParser(ParsersConst.jpm);
    }
}

@Component
public class StaticFacotryDemo implements CommandLineRunner {
    @Autowired
    private ApplicationContext context;

    @Override
    public void run(String... args) throws Exception {

        Parser parser = (Parser) context.getBean(ParsersConst.jpm.toString());
        System.out.println(parser.readFromFile("jan_stmt.pdf"));

    }

}

基于注释的工厂方法

5 个答案: