Java HTTP函数 - 函数计算

HTTP函数接口

函数计算提供基于Servlet协议的HTTP入口，形式如下所示。

public interface HttpRequestHandler {
    /**
     * The entrance function of fc http trigger 
     * @param request The servlet request
     * @param response The servlet response
     * @param context The fc context
     * @throws IOException If IO exception happened
     * @throws ServletException If servlet exception happened
     */
    public void handleRequest(HttpServletRequest request, HttpServletResponse response, Context context) throws IOException, ServletException;
}      

使用HTTP触发器需要将fc-java-core库版本升级到1.3.0及以上。

HTTP触发器的简单示例

package com.aliyun.fc.example;

import java.io.IOException;
import java.io.OutputStream;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.aliyun.fc.runtime.Context;
import com.aliyun.fc.runtime.HttpRequestHandler;

public class Hello implements HttpRequestHandler {
    public void handleRequest(HttpServletRequest request, HttpServletResponse response, Context context)
            throws IOException, ServletException {
        String requestPath = (String) request.getAttribute("FC_REQUEST_PATH");
        String requestURI = (String) request.getAttribute("FC_REQUEST_URI");
        String requestClientIP = (String) request.getAttribute("FC_REQUEST_CLIENT_IP"); 

        response.setStatus(200);
        response.setHeader("header1", "value1");
        response.setHeader("header2", "value2");

        String body = String.format("Path: %s\n Uri: %s\n IP: %s\n", requestPath, requestURI, requestClientIP);
        OutputStream out = response.getOutputStream();
        out.write((body).getBytes());
        out.flush();
        out.close();
    }
}          

• HttpServletRequest

  函数计算HTTP触发器的接口使用标准的Servlet协议。您的请求会封装成HttpServletRequest对象，请求参数、请求头等均可通过此对象获取。除此之外，函数计算在HttpServletRequest中预封装了一些属性，您可以通过getAttribute方法来获取，具体包括以下内容：

  • FC_REQUEST_PATH：获取请求的路径。

  • FC_REQUEST_URI：获取请求的URI。

  • FC_REQUEST_CLIENT_IP：获取请求的Client IP地址。

• HttpServletResponse

  您可以通过标准的HttpServletResponse协议对象来返回响应头和响应体。

• context参数

  context参数中包含一些函数的运行时信息（例如Request ID、临时AccessKey等），其类型是com.aliyun.fc.runtime.Context。

HTTP触发器支持传统Web应用

基于Servlet协议的传统Web应用能很方便地迁移到函数计算平台，目前支持的主流框架包括Spring、SpringBoot、Struts2等。以下示例演示如何通过函数计算提供的fc-java-common库加载Web应用。

1. 打包您的Web工程，生成demo.war。
2. 上传demo.war包到OSS，例如上传到demo-bucket目录下。
3. 创建函数，并设置函数Initializer入口和入口函数。

   • 函数示例代码如下。

     package com.aliyun.fc.example;
     
     import java.io.IOException;
     
     import javax.servlet.ServletException;
     import javax.servlet.http.HttpServletRequest;
     import javax.servlet.http.HttpServletResponse;
     
     import com.aliyun.fc.runtime.Context;
     import com.aliyun.fc.runtime.FcAppLoader;
     import com.aliyun.fc.runtime.FunctionComputeLogger;
     import com.aliyun.fc.runtime.FunctionInitializer;
     import com.aliyun.fc.runtime.HttpRequestHandler;
     
     public class HelloWeb implements FunctionInitializer, HttpRequestHandler {
       private FcAppLoader fcAppLoader = new FcAppLoader();
     
       private String ossEndPoint = "YourOSSEndPoint";
       private String bucket = "YourOSSBucket";
       private String key = "YourWarName";
       private String userContextPath = "/2016-08-15/proxy/{YourServiceName}/{YourFunctionName}";
     
       @Override
       public void initialize(Context context) throws IOException {
             FunctionComputeLogger fcLogger = context.getLogger();
     
             fcAppLoader.setFCContext(context);
     
             // Load code from OSS
             fcAppLoader.loadCodeFromOSS(ossEndPoint, bucket, key);
     
             // Init webapp from code
             fcAppLoader.initApp(userContextPath, HelloWeb.class.getClassLoader());
       }
     
       @Override
       public void handleRequest(HttpServletRequest request, HttpServletResponse response, Context context)
                 throws IOException, ServletException {
             try {
                 fcAppLoader.forward(request, response);
             } catch (Exception e) {
                 e.printStackTrace();
             }
       }
     }                            

   • 引用Maven库

      <dependency>
           <groupId>com.aliyun.fc.runtime</groupId>
           <artifactId>fc-java-core</artifactId>
           <version>1.3.0</version>
       </dependency>
     
       <dependency>
           <groupId>com.aliyun.fc.runtime</groupId>
           <artifactId>fc-java-common</artifactId>
           <version>2.2.2</version>
       </dependency>                  

更多信息

HTTP触发器的使用，请参见HTTP触发器概述。