如何读取用Java编写的AWS Lambda函数中的文件？ [英] How to read a file in AWS Lambda Function written in Java ?

问题描述

我编写了一个AWS Lambda Handler，如下所示：

  package com.lambda; 
 import com.amazonaws.services.lambda.runtime.Context; 
 import com.amazonaws.services.lambda.runtime.LambdaLogger; 
 import com.amazonaws.services.lambda.runtime.RequestStreamHandler; 
 import java.io. *; 
 
公共类TestDetailsHandler实现RequestStreamHandler {
 
 
 public void handleRequest（InputStream input，OutputStream output，Context context）{
 
 //获取Lambda Logger 
 LambdaLogger logger = context.getLogger（）; 
 
 //接收来自Inputstream的输入抛出异常，如果有任何
 
文件起始=新文件（System.getProperty（user.dir））; 
 System.out.println（源位置+开始）; 
 
文件cityFile = new文件（起始+City.db）; 
 FileInputStream fis = null; 
 
 try {
 fis = new FileInputStream（cityFile）; 
 
 System.out.println（要读取的文件总大小（以字节为单位）：
 + fis.available（））; 
 
 int content; 
 while（（content = fis.read（））！= -1）{
 //转换为char并显示它
 System.out.print（（char）content）; 
} 
 
} catch（IOException e）{
 e.printStackTrace（）; 
} finally {
 try {
 if（fis！= null）
 fis.close（）; 
} catch（IOException ex）{
 ex.printStackTrace（）; 
} 
} 
} 
 
} 
  

它读取了一个文件：City.db，在资源文件夹中可用，即使我一直到处都看到如下：

Pom.xml文件的内容：

 <？xml version =1.0encoding =UTF-8？> 
< project xmlns =http://maven.apache.org/POM/4.0.0
 xmlns：xsi =http://www.w3.org/2001/XMLSchema-instance 
 xsi：schemaLocation =http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd\"> 
< modelVersion> 4.0.0< / modelVersion> 
 
< groupId> com.lambda< / groupId> 
< artifactId> testdetails< / artifactId> 
< version> 1.0-SNAPSHOT< / version> 
< packaging> jar< / packaging> 
< name> test-handler< / name> 
 
< dependencies> 
< dependency> 
< groupId> com.amazonaws< / groupId> 
< artifactId> aws-lambda-java-core< / artifactId> 
< version> 1.1.0< / version> 
< / dependency> 
 
<依赖> 
< groupId> junit< / groupId> 
< artifactId> junit< / artifactId> 
< version> 4.11< / version> 
< scope> test< / scope> 
< / dependency> 
 
 
 
< / dependencies> 
 
< build> 
< plugins> 
< plugin> 
< groupId> org.apache.maven.plugins< / groupId> 
< artifactId> maven-shade-plugin< / artifactId> 
< version> 2.3< / version> 
< configuration> 
< createDependencyReducedPom> false< / createDependencyReducedPom> 
< / configuration> 
< executions> 
< execution> 
< phase> package< / phase> 
< goals> 
< goal> shade< / goal> 
< / goals> 
< / execution> 
< / executions> 
< / plugin> 
< / plugins> 
< / build> 
< / project> 
  

我已经使用各种方法来保存文件，但最后它无法正常工作。请你告诉我这里有什么问题？

然而在我的另一个项目中，我将xyz.properties文件保存在resources文件夹中并从PropertyManager文件中读取，工作正常。当我在我的系统上测试它工作正常，但在AWS Lambda函数上它不起作用。

解决方案

我在代码中进行了以下更改，现在它的工作非常完美：

主要更改以下两行：

ClassLoader classLoader = getClass（）。getClassLoader（）;

文件cityFile =新文件（classLoader.getResource（City.db）。getFile（））;

  package com.lambda; 
 
 
 import com.amazonaws.services.lambda.runtime.Context; 
 import com.amazonaws.services.lambda.runtime.LambdaLogger; 
 import com.amazonaws.services.lambda.runtime.RequestStreamHandler; 
 import java.io. *; 
 
公共类TestDetailsHandler实现RequestStreamHandler {
 
 
 public void handleRequest（InputStream input，OutputStream output，Context context）{
 
 //获取Lambda Logger 
 LambdaLogger logger = context.getLogger（）; 
 
 //如果任何
 
 ClassLoader classLoader = getClass（）。getClassLoader（）;接收来自Inputstream抛出异常的输入。 
 
文件cityFile = new File（classLoader.getResource（City.db）。getFile（））; 
 FileInputStream fis = null; 
 
 try {
 fis = new FileInputStream（cityFile）; 
 
 System.out.println（要读取的文件总大小（以字节为单位）：
 + fis.available（））; 
 
 int content; 
 while（（content = fis.read（））！= -1）{
 //转换为char并显示它
 System.out.print（（char）content）; 
} 
 
} catch（IOException e）{
 e.printStackTrace（）; 
} finally {
 try {
 if（fis！= null）
 fis.close（）; 
} catch（IOException ex）{
 ex.printStackTrace（）; 
} 
} 
} 
  

I have written an AWS Lambda Handler as below :

package com.lambda;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
import com.amazonaws.services.lambda.runtime.RequestStreamHandler;
import java.io.*;

public class TestDetailsHandler implements RequestStreamHandler {


    public void  handleRequest(InputStream input,OutputStream output,Context context){

        // Get Lambda Logger
        LambdaLogger logger = context.getLogger();

        // Receive the input from Inputstream throw exception if any

        File starting = new File(System.getProperty("user.dir"));
            System.out.println("Source Location" + starting);

           File cityFile = new File(starting + "City.db");
        FileInputStream fis = null;

        try {
            fis = new FileInputStream(cityFile);

            System.out.println("Total file size to read (in bytes) : "
                    + fis.available());

            int content;
            while ((content = fis.read()) != -1) {
                // convert to char and display it
                System.out.print((char) content);
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (fis != null)
                    fis.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    }

}

Its read a file : City.db , available in resources folder, even I kept to everywhere see below :

But it showing following message on execution of this lambda function :

START RequestId: 5216ea47-fc43-11e5-96d5-83c1dcdad75d Version: $LATEST
Source Location/
java.io.FileNotFoundException: /city.db (No such file or directory)
    at java.io.FileInputStream.open0(Native Method)
    at java.io.FileInputStream.open(FileInputStream.java:195)
    at java.io.FileInputStream.<init>(FileInputStream.java:138)
    at com.lambda.TestDetailsHandler.handleRequest(TestDetailsHandler.java:26)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at lambdainternal.EventHandlerLoader$StreamMethodRequestHandler.handleRequest(EventHandlerLoader.java:511)
    at lambdainternal.EventHandlerLoader$2.call(EventHandlerLoader.java:972)
    at lambdainternal.AWSLambda.startRuntime(AWSLambda.java:231)
    at lambdainternal.AWSLambda.<clinit>(AWSLambda.java:59)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:348)
    at lambdainternal.LambdaRTEntry.main(LambdaRTEntry.java:93)
END RequestId: 5216ea47-fc43-11e5-96d5-83c1dcdad75d
REPORT RequestId: 5216ea47-fc43-11e5-96d5-83c1dcdad75d  Duration: 58.02 ms  Billed Duration: 100 ms     Memory Size: 1024 MB    Max Memory Used: 50 MB  

Contents of the Pom.xml file :

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.lambda</groupId>
    <artifactId>testdetails</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>test-handler</name>

    <dependencies>
        <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-lambda-java-core</artifactId>
            <version>1.1.0</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>



        </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.3</version>
                <configuration>
                    <createDependencyReducedPom>false</createDependencyReducedPom>
                </configuration>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

I have used various ways to keep file here and there , but at the end its not working. May you please let me know what is wrong here ?

However in my another project where I have kept xyz.properties file in resources folder and reading from a PropertyManager file, its working fine. When I tested it on my system its working fine, but on AWS Lambda function it doesn't work.

解决方案

I have made following changes in my code and now its works perfect :

Majorly changed following two lines :

ClassLoader classLoader = getClass().getClassLoader();

File cityFile = new File(classLoader.getResource("City.db").getFile());

package com.lambda;


import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
import com.amazonaws.services.lambda.runtime.RequestStreamHandler;
import java.io.*;

public class TestDetailsHandler implements RequestStreamHandler {


    public void  handleRequest(InputStream input,OutputStream output,Context context){

        // Get Lambda Logger
        LambdaLogger logger = context.getLogger();

        // Receive the input from Inputstream throw exception if any

        ClassLoader classLoader = getClass().getClassLoader();

        File cityFile = new File(classLoader.getResource("City.db").getFile());
        FileInputStream fis = null;

        try {
            fis = new FileInputStream(cityFile);

            System.out.println("Total file size to read (in bytes) : "
                    + fis.available());

            int content;
            while ((content = fis.read()) != -1) {
                // convert to char and display it
                System.out.print((char) content);
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (fis != null)
                    fis.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    }

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