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编写处理GetObject请求的函数

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通过对象FC接入点访问GetObject API时，将触发您所绑定的函数计算服务中的函数，并在函数中配合WriteGetObjectResponse接口实现自定义返回数据和响应标头。

前提条件

  • 已创建对象FC接入点。具体操作，请参见创建对象FC接入点。

  • OSS Java SDK为3.17.2及以上版本。

  • OSS Python SDK为2.18.3及以上版本。

操作步骤

  1. 编写处理GetObject请求的函数示例。

    示例一：通过转换后的图片进行响应

    Java

    import com.aliyun.fc.runtime.Context;
import com.aliyun.fc.runtime.Credentials;
import com.aliyun.fc.runtime.StreamRequestHandler;
import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.ObjectMetadata;
import com.aliyun.oss.model.VoidResult;
import com.aliyun.oss.model.WriteGetObjectResponseRequest;
import org.codehaus.jettison.json.JSONException;
import org.codehaus.jettison.json.JSONObject;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Scanner;

public class Example1 implements StreamRequestHandler {
    // Endpoint以华北1（青岛）为例。
    String endpoint = "https://oss-cn-qingdao.aliyuncs.com";
    private static int status = 200;

    public static String convertToString(InputStream inputStream) {
        Scanner scanner = new Scanner(inputStream).useDelimiter("\\A");
        return scanner.hasNext() ? scanner.next() : "";
    }

    @Override
    public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
        Credentials creds = context.getExecutionCredentials();
        // 从上下文中获取访问密钥。
        OSS ossClient = new OSSClientBuilder().build(endpoint, creds.getAccessKeyId(), creds.getAccessKeySecret(), creds.getSecurityToken());


        try {
            String result = convertToString(inputStream);
            JSONObject jsonObject = new JSONObject(result);
            String route = jsonObject.getJSONObject("getObjectContext").getString("outputRoute");
            String token = jsonObject.getJSONObject("getObjectContext").getString("outputToken");
            // 通过调用BufferedImage创建200*200像素的对象，并为该对象绘制红色的矩形框。
            // 完成以上调整后，将内容写入WriteGetObjectResponse请求的主体中。
            BufferedImage image = new BufferedImage(200, 200, BufferedImage.TYPE_INT_RGB);
            Graphics2D graphics = image.createGraphics();
            graphics.setColor(Color.RED);
            graphics.fillRect(0, 0, 200, 200);
            graphics.dispose();

            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ImageIO.write(image, "png", baos);
            WriteGetObjectResponseRequest writeGetObjectResponseRequest = new WriteGetObjectResponseRequest(route, token, status,new ByteArrayInputStream(baos.toByteArray()));

            ObjectMetadata metadata = new ObjectMetadata();
            metadata.setContentLength(baos.size());
            writeGetObjectResponseRequest.setMetadata(metadata);

            VoidResult voidResult = ossClient.writeGetObjectResponse(writeGetObjectResponseRequest);
            System.out.println("getRequestId："+voidResult.getRequestId());
            System.out.println("status："+voidResult.getResponse().getStatusCode());
            System.out.println("Headers："+voidResult.getResponse().getHeaders().toString());
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message: " + oe.getMessage());
            System.out.println("Error Code:       " + oe.getErrorCode());
            System.out.println("Request ID:      " + oe.getRequestId());
            System.out.println("Host ID:           " + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message: " + ce.getMessage());
        } catch (JSONException e) {
            e.printStackTrace();
        } finally {
            ossClient.shutdown();
        }
    }
}

    Python

    # -*- coding: utf-8 -*-
import io
from PIL import Image
import oss2
import json

# Endpoint以华北1（青岛）为例。
endpoint = 'http://oss-cn-qingdao.aliyuncs.com'
fwd_status = '200'

# Fc function entry
def handler(event, context):

    evt = json.loads(event)
    creds = context.credentials
    # do not forget security_token
    auth = oss2.StsAuth(creds.access_key_id, creds.access_key_secret, creds.security_token)

    headers = dict()    

    event_ctx = evt["getObjectContext"]
    route = event_ctx["outputRoute"]
    token = event_ctx["outputToken"]
    print(evt)

    endpoint = route
    service = oss2.Service(auth, endpoint)
    # 通过调用Image方法创建200*200像素的对象，并为该对象绘制红色的矩形框。
    # 完成以上调整后，将内容写入write_get_object_response请求的主体中。
    image = Image.new('RGB', (200, 200), color=(255, 0, 0))
    transformed = io.BytesIO()
    image.save(transformed, "png")

    resp = service.write_get_object_response(route, token, fwd_status, transformed.getvalue(), headers)

    print('status: {0}'.format(resp.status))
    print(resp.headers)

    return 'success'

    示例二：通过压缩内容进行响应

    Java

    import com.aliyun.fc.runtime.Context;
import com.aliyun.fc.runtime.Credentials;
import com.aliyun.fc.runtime.StreamRequestHandler;
import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.OSSObject;
import com.aliyun.oss.model.ObjectMetadata;
import com.aliyun.oss.model.VoidResult;
import com.aliyun.oss.model.WriteGetObjectResponseRequest;
import org.codehaus.jettison.json.JSONException;
import org.codehaus.jettison.json.JSONObject;
import java.io.*;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class Example2 implements StreamRequestHandler {
    // Endpoint以华北1（青岛）为例。
    String endpoint = "https://oss-cn-qingdao.aliyuncs.com";
    // 填写object名称。
    String fileName = "examplefile.txt";
    // 本地临时生成的压缩包路径。
    String path = "test.zip";
    private static int status = 200;

    public static String convertToString(InputStream inputStream) {
        Scanner scanner = new Scanner(inputStream).useDelimiter("\\A");
        return scanner.hasNext() ? scanner.next() : "";
    }

    public static void convertToZip(InputStream inputStream, String fileName, String path) throws IOException {
        FileOutputStream fos = new FileOutputStream(path);
        ZipOutputStream zipOut = new ZipOutputStream(fos);
        ZipEntry zipEntry = new ZipEntry(fileName);
        zipOut.putNextEntry(zipEntry);

        byte[] bytes = new byte[1024];
        int length;
        while((length = inputStream.read(bytes)) >= 0) {
            zipOut.write(bytes, 0, length);
        }

        zipOut.close();
        inputStream.close();
        fos.close();
    }

    @Override
    public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
        Credentials creds = context.getExecutionCredentials();
        // 从上下文中获取访问密钥。
        System.out.println("getAccessKeyId: "+creds.getAccessKeyId());
        System.out.println("getAccessKeySecret: "+creds.getAccessKeySecret());
        OSS ossClient = new OSSClientBuilder().build(endpoint, creds.getAccessKeyId(), creds.getAccessKeySecret(), creds.getSecurityToken());

        try {
            String result = convertToString(inputStream);
            JSONObject jsonObject = new JSONObject(result);
            String route = jsonObject.getJSONObject("getObjectContext").getString("outputRoute");
            String token = jsonObject.getJSONObject("getObjectContext").getString("outputToken");
            String inputOssUrl = jsonObject.getJSONObject("getObjectContext").getString("inputOssUrl");

            System.out.println("jsonObject："+jsonObject);
            System.out.println("inputOssUrl: "+inputOssUrl);

            Map<String, String> customHeaders = new HashMap<String, String>();
            URL signedUrl = new URL(inputOssUrl);
            OSSObject ossObject = ossClient.getObject(signedUrl, customHeaders);
            System.out.println("getObject StatusCode: "+ossObject.getResponse().getStatusCode());

            // 把通过签名url获取到的文件进行压缩后上传。
            convertToZip(ossObject.getObjectContent(), fileName, path);
            File file = new File(path);
            FileInputStream fis = new FileInputStream(file);

            WriteGetObjectResponseRequest writeGetObjectResponseRequest = new WriteGetObjectResponseRequest(route, token, status, fis);

            ObjectMetadata metadata = new ObjectMetadata();
            metadata.setContentLength(file.length());
            writeGetObjectResponseRequest.setMetadata(metadata);

            VoidResult voidResult = ossClient.writeGetObjectResponse(writeGetObjectResponseRequest);
            System.out.println("getRequestId："+voidResult.getRequestId());
            System.out.println("status："+voidResult.getResponse().getStatusCode());
            System.out.println("Headers："+voidResult.getResponse().getHeaders().toString());
            // 删除临时生成的压缩包。
            file.delete();
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message: " + oe.getMessage());
            System.out.println("Error Code:       " + oe.getErrorCode());
            System.out.println("Request ID:      " + oe.getRequestId());
            System.out.println("Host ID:           " + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message: " + ce.getMessage());
        } catch (JSONException e) {
            e.printStackTrace();
        } finally {            
            ossClient.shutdown();
        }
    }
}

    Python

    # -*- coding: utf-8 -*-
import os
import oss2
import json
import gzip
import requests
# Endpoint以华北1（青岛）为例。
endpoint = 'http://oss-cn-qingdao.aliyuncs.com'
fwd_status = '200'

# 填写object名称。
fileName = "examplefile.txt"
# 本地临时生成的压缩包路径。
path = 'test.zip'

def handler(event, context):

    evt = json.loads(event)
    creds = context.credentials
    # 从上下文中获取访问密钥。
    auth = oss2.StsAuth(creds.access_key_id, creds.access_key_secret, creds.security_token)

    headers = dict()  

    event_ctx = evt["getObjectContext"]
    route = event_ctx["outputRoute"]
    token = event_ctx["outputToken"]
    inputOssUrl = event_ctx["inputOssUrl"]
    print(evt)

    endpoint = route   
    resp = requests.get(inputOssUrl)

    # 把通过签名URL获取到的文件进行压缩后上传。
    g = gzip.GzipFile(filename=fileName, mode="wb", compresslevel=9, fileobj=open(path, 'wb'))
    g.write(resp.content)
    g.close()

    service = oss2.Service(auth, endpoint)
    with open(path, 'rb') as fileobj:
        resp = service.write_get_object_response(route, token, fwd_status, fileobj, headers)
        print('status: {0}'.format(resp.status))
        print(resp.headers)

    # 删除临时生成的压缩包。
    os.remove(path)
    return 'success'

  2. 部署函数。

    Java

    1. 自行打包.jar文件。

    2. 将.jar文件上传至函数计算控制台。

      1. 登录函数计算控制台，单击右上角返回函数计算2.0。

      2. 在左侧导航栏，单击服务及函数。

      3. 在顶部导航栏，选择华北1（青岛）地域。

      4. 在服务列表页面，单击已创建的服务，然后单击已创建的运行环境为Java 11的函数。

      5. 在函数详情页面，选择上传代码 > 上传JAR包。

      6. 在弹出的对话框，选择已打包的.jar文件，勾选我想在选中文件后直接部署函数，然后单击保存并部署。

    3. 根据函数示例对应修改请求处理程序（函数入口）。

      1. 在函数详情页面，单击函数配置页签。

      2. 在环境信息区域，单击编辑。

      3. 修改请求处理程序（函数入口）。

        当运行环境为Java时，当前值的格式为[package].[class]::[method]。如果当前值为 example.HelloFC::handleRequest，则在函数被触发时，将执行example包中HelloFC类下的handleRequest函数。您需要根据处理GetObject请求的函数示例的实际情况修改当前值，例如com.aliyun.sts.sample.Example1::handleRequest。

    Python

    1. 在服务列表页面，单击已创建的服务，然后单击已创建的运行环境为Python 3.10的函数。

    2. 在函数详情页面，单击函数代码页签，然后选择Terminal > New Terminal 。

    3. 在TERMINAL面板，输入以下命令更新OSS Python SDK版本。

      pip install oss2 -t .

    4. 将index.py中的代码示例替换为Python处理GetObject请求的函数示例，然后单击部署函数。

后续步骤

使用对象FC接入点

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