高效 告别996，开启java高效编程之门 2-10实战：自定义函数式接口

Posted 2020-11-27 扈江离与辟芷兮，纫秋兰以为佩。

1　有用部分

2    代码演练

 

 

1　　有用部分

个人理解：

1.1　　关于lambda的应用

通过 @FunctionalInterface注解 将其参数 fileContent  注入，调用的时候可以直接调取到。

服务层通过直接调用接口的方法，没有用实现类

 

1.2　　关于文件流的读取操作

demo中设计更多的流的读取的操作

 

 

2　　代码演练

需求：

将本地文件打印出来

 

接口：

 

package com.imooc.zhangxiaoxi.lambda.file;

/**
 *  接口中只有一个抽象方法，可以应用lambda表达式
 *
 *  加入注解
 *
 *  文件处理函数式接口
 */
@FunctionalInterface
public interface FileConsumer {

    /**
     * 函数式接口抽象方法
     * @param fileContent
     */
    void fileHandler(String fileContent);

}

 

 

 

文件服务类：

 

package com.imooc.zhangxiaoxi.lambda.file;

import java.io.*;

/**
 * 文件服务类
 */
public class FileService {

    /**
     * 根据url获取文件，打印文件内容
     */
    public void print(String url,FileConsumer fileConsumer) throws IOException {

        //流读取
        BufferedReader bufferedReader = new BufferedReader(
                new InputStreamReader(
                        new FileInputStream(url)));

        //定义行变量和内容sb
        String line =  "";
        StringBuilder stringBuilder = new StringBuilder();

        //循环读取文件内容
        while((line=bufferedReader.readLine())!=null){
            stringBuilder.append(line+"
");
        }

        //调用函数式接口方法，将文件内容传递给lambda表达式
        fileConsumer.fileHandler(stringBuilder.toString());

    }
}

 

 

 

 

文件测试类：

 

package com.imooc.zhangxiaoxi.lambda.file;

import org.junit.Test;

import java.io.IOException;

public class FileServiceTest {


    @Test
    public void Test() throws IOException {

　　　　 //两种方式
　　
        //1.2
        FileService fileService = new FileService();
        fileService.print("F:/xiangmu3/Xin/test996/src/test/java/com/imooc/zhangxiaoxi/" +
                        "lambda/file/FileServiceTest.java",
                fileContent -> {
            System.out.println(fileContent);
        });

       //1.1
        /*FileService fileService = new FileService();
        fileService.print("F:/xiangmu3/Xin/test996/src/test/java/com/imooc/zhangxiaoxi/" +
                "lambda/file/FileServiceTest.java",
                fileContent -> System.out.println(fileContent));*/
    }

}

 

 

 

打印日志：

D:javajdkjdk9jdk-9+181_windows-x64_rijava-se-9-rijdk-9injava.exe -ea -Didea.test.cyclic.buffer.size=1048576 "-javaagent:D:javadevolopKitideaanZhIntelliJ IDEA Community Edition 2018.1.4libidea_rt.jar=30991:D:javadevolopKitideaanZhIntelliJ IDEA Community Edition 2018.1.4in" -Dfile.encoding=UTF-8 -classpath "D:javadevolopKitideaanZhIntelliJ IDEA Community Edition 2018.1.4libidea_rt.jar;D:javadevolopKitideaanZhIntelliJ IDEA Community Edition 2018.1.4pluginsjunitlibjunit-rt.jar;D:javadevolopKitideaanZhIntelliJ IDEA Community Edition 2018.1.4pluginsjunitlibjunit5-rt.jar;F:xiangmu3Xin	est996	arget	est-classes;F:xiangmu3Xin	est996	argetclasses;F:xiangmu3Xin	est996libcomgoogleguavaguava28.2-jreguava-28.2-jre.jar;F:xiangmu3Xin	est996libcomgoogleguavafailureaccess1.0.1failureaccess-1.0.1.jar;F:xiangmu3Xin	est996libcomgoogleguavalistenablefuture9999.0-empty-to-avoid-conflict-with-guavalistenablefuture-9999.0-empty-to-avoid-conflict-with-guava.jar;F:xiangmu3Xin	est996libcomgooglecodefindbugsjsr3053.0.2jsr305-3.0.2.jar;F:xiangmu3Xin	est996liborgcheckerframeworkchecker-qual2.10.0checker-qual-2.10.0.jar;F:xiangmu3Xin	est996libcomgoogleerrorproneerror_prone_annotations2.3.4error_prone_annotations-2.3.4.jar;F:xiangmu3Xin	est996libcomgooglej2objcj2objc-annotations1.3j2objc-annotations-1.3.jar;F:xiangmu3Xin	est996libjunitjunit4.12junit-4.12.jar;F:xiangmu3Xin	est996liborghamcresthamcrest-core1.3hamcrest-core-1.3.jar;F:xiangmu3Xin	est996libcomalibabafastjson1.2.58fastjson-1.2.58.jar" com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.imooc.zhangxiaoxi.lambda.file.FileServiceTest,Test
package com.imooc.zhangxiaoxi.lambda.file;

import org.junit.Test;

import java.io.IOException;

public class FileServiceTest {


    @Test
    public void Test() throws IOException {
        //1.2
        FileService fileService = new FileService();
        fileService.print("F:/xiangmu3/Xin/test996/src/test/java/com/imooc/zhangxiaoxi/" +
                        "lambda/file/FileServiceTest.java",
                fileContent -> {
            System.out.println(fileContent);
        });

       //1.1
        /*FileService fileService = new FileService();
        fileService.print("F:/xiangmu3/Xin/test996/src/test/java/com/imooc/zhangxiaoxi/" +
                "lambda/file/FileServiceTest.java",
                fileContent -> System.out.println(fileContent));*/
    }

}


Process finished with exit code 0