創建一個Amazon Lambda函數，實現從S3源存儲桶讀取圖片對象並創建縮略圖到目標存儲桶，開發實現過程如下：
1、創建存儲桶並上傳示例對象
（1）打開 Amazon S3 控制檯
（2）創建兩個存儲桶。源存儲桶lambda-demo1-bucket，目標存儲桶lambda-demo1-bucketresized。
（3）在源存儲桶中，上傳一個 .jpg 對象 sidatianwang.jpg。
2、創建Lambda函數
（1）創建Maven項目，pom.xml中添加如下：
<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.lenovo</groupId>
<artifactId>lambda</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>lambda</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>net.lingala.zip4j</groupId>
<artifactId>zip4j</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-core</artifactId>
<version>1.2.0</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-events</artifactId>
<version>2.2.2</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-core</artifactId>
<version>1.11.520</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-s3</artifactId>
<version>1.11.520</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-lambda</artifactId>
<version>1.11.520</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-codebuild</artifactId>
<version>1.11.745</version>
</dependency>
<!-- <dependency>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>3.2.1</version>
</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>
（2）編寫主函數，接收Amazon S3事件輸入並對其包含的消息進行處理。
package example;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.imageio.ImageIO;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.S3Event;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.event.S3EventNotification.S3EventNotificationRecord;
import com.amazonaws.services.s3.model.GetObjectRequest;
import com.amazonaws.services.s3.model.ObjectMetadata;
import com.amazonaws.services.s3.model.S3Object;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
public class Handler implements RequestHandler<S3Event, String> {
private static final float MAX_WIDTH = 100;
private static final float MAX_HEIGHT = 100;
private final String JPG_TYPE = (String) "jpg";
private final String JPG_MIME = (String) "image/jpeg";
private final String PNG_TYPE = (String) "png";
private final String PNG_MIME = (String) "image/png";
public String handleRequest(S3Event s3event, Context context) {
try {
S3EventNotificationRecord record = s3event.getRecords().get(0);
String srcBucket = record.getS3().getBucket().getName();
// Object key may have spaces or unicode non-ASCII characters.
String srcKey = record.getS3().getObject().getUrlDecodedKey();
String dstBucket = srcBucket + "resized";
String dstKey = "resized-" + srcKey;
// Sanity check: validate that source and destination are different
// buckets.
if (srcBucket.equals(dstBucket)) {
System.out.println("Destination bucket must not match source bucket.");
return "";
}
// Infer the image type.
Matcher matcher = Pattern.compile(".*\\.([^\\.]*)").matcher(srcKey);
if (!matcher.matches()) {
System.out.println("Unable to infer image type for key " + srcKey);
return "";
}
String imageType = matcher.group(1);
if (!(JPG_TYPE.equals(imageType)) && !(PNG_TYPE.equals(imageType))) {
System.out.println("Skipping non-image " + srcKey);
return "";
}
// Download the image from S3 into a stream
AmazonS3 s3Client = AmazonS3ClientBuilder.defaultClient();
S3Object s3Object = s3Client.getObject(new GetObjectRequest(srcBucket, srcKey));
InputStream objectData = s3Object.getObjectContent();
// Read the source image
BufferedImage srcImage = ImageIO.read(objectData);
int srcHeight = srcImage.getHeight();
int srcWidth = srcImage.getWidth();
// Infer the scaling factor to avoid stretching the image
// unnaturally
float scalingFactor = Math.min(MAX_WIDTH / srcWidth, MAX_HEIGHT / srcHeight);
int width = (int) (scalingFactor * srcWidth);
int height = (int) (scalingFactor * srcHeight);
BufferedImage resizedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g = resizedImage.createGraphics();
// Fill with white before applying semi-transparent (alpha) images
g.setPaint(Color.white);
g.fillRect(0, 0, width, height);
// Simple bilinear resize
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(srcImage, 0, 0, width, height, null);
g.dispose();
// Re-encode image to target format
ByteArrayOutputStream os = new ByteArrayOutputStream();
ImageIO.write(resizedImage, imageType, os);
InputStream is = new ByteArrayInputStream(os.toByteArray());
// Set Content-Length and Content-Type
ObjectMetadata meta = new ObjectMetadata();
meta.setContentLength(os.size());
if (JPG_TYPE.equals(imageType)) {
meta.setContentType(JPG_MIME);
}
if (PNG_TYPE.equals(imageType)) {
meta.setContentType(PNG_MIME);
}
// Uploading to S3 destination bucket
System.out.println("Writing to: " + dstBucket + "/" + dstKey);
try {
s3Client.putObject(dstBucket, dstKey, is, meta);
} catch (AmazonServiceException e) {
System.err.println(e.getErrorMessage());
System.exit(1);
}
System.out.println("Successfully resized " + srcBucket + "/" + srcKey + " and uploaded to " + dstBucket
+ "/" + dstKey);
return "Ok";
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
（3）將maven工程打成jar包（以eclipse爲例說明）
a. 清理，工程點擊右鍵 → run as → Maven clean
b. 打包，工程點擊右鍵 → run as → Maven install
在target目錄下獲取生成的jar包lambda-0.0.1-SNAPSHOT.jar
（4）登錄Amazon lambda服務控制檯，創建lambda測試函數
a. 名稱隨意；
b. 選擇語言；
c. 選擇或創建角色，角色要有lambda執行權限。
d. 上傳jar包lambda-0.0.1-SNAPSHOT.jar
注意處理程序命名規則：包.類::方法名（例如：example.Handler::handleRequest）
e. 添加S3觸發器，通過S3事件觸發調用lambda函數
f. 點擊保存，保存lambda函數
3、配置S3事件通知
（1）打開 Amazon S3 控制檯，依次執行：選擇源存儲桶→選擇屬性→高級選項卡下選擇事件→添加通知
（2）在 Events (事件) 下，使用以下設置配置通知。
名稱 – lambda-trigger；
事件 – ObjectCreate (All)；
發送到 – Lambda function；
Lambda – test10。
4、點擊測試，編寫測試用例。
（1）點擊配置測試事件，填寫測試用例。（json格式，對應方法的參數）
{
"Records": [
{
"eventVersion": "2.0",
"eventSource": "aws:s3",
"awsRegion": "ap-southeast-1",
"eventTime": "1970-01-01T00:00:00.000Z",
"eventName": "ObjectCreated:Put",
"userIdentity": {
"principalId": "EXAMPLE"
},
"requestParameters": {
"sourceIPAddress": "127.0.0.1"
},
"responseElements": {
"x-amz-request-id": "EXAMPLE123456789",
"x-amz-id-2": "EXAMPLE123/5678abcdefghijklambdaisawesome/mnopqrstuvwxyzABCDEFGH"
},
"s3": {
"s3SchemaVersion": "1.0",
"configurationId": "testConfigRule",
"bucket": {
"name": "lambda-demo1-bucket",
"ownerIdentity": {
"principalId": "*"
},
"arn": "arn:aws:s3:::lambda-demo1-bucket"
},
"object": {
"key": "sidatianwang.jpg",
"size": 1024,
"eTag": "0123456789abcdef0123456789abcdef",
"sequencer": "0A1B2C3D4E5F678901"
}
}
}
]
}
（2）點擊測試按鈕，即可運行
（3）返回Amazon S3控制檯，驗證目標存儲桶中是否生成縮略圖
經過驗證發現，將圖片sidatianwang.jpg上傳到S3源存儲桶lambda-demo1-bucket後，通過S3事件觸發lambda函數test10，在S3目標存儲桶lambda-demo1-bucketresized中生成了縮略圖resized-sidatianwang.jpg。