java实现将ftp和http的文件直接传送到hdfs

讲解“Java实现将FTP和HTTP的文件直接传送到HDFS”的完整攻略，步骤如下：

1.导入必要的依赖项

对于将FTP和HTTP文件传送到HDFS，我们需要使用一些必要的Java包和库。其中，Java对于FTP协议的支持已经包括在Java自带的JDK中了。而对于HTTP协议的支持，我们可以通过引入Apache HttpClient的库来实现。对于HDFS的操作，我们则需要引入Hadoop HDFS的Java API——即hadoop-client库。

在Maven项目中，添加如下依赖：

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version>
</dependency>
<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-client</artifactId>
    <version>3.3.1</version>
</dependency>

2.编写代码传输FTP文件到HDFS

可以使用Apache Commons Net库来处理FTP文件传输。以下是一个示例：

// 引入必要的类
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import java.io.*;

public class FtpToHdfs {
    // FTP服务器连接信息
    private final static String FTP_SERVER = "ftp.example.com";
    private final static String FTP_USERNAME = "ftpuser";
    private final static String FTP_PASSWORD = "ftppassword";
    private final static String FILE_PATH = "/path/to/ftp/file.txt";
    // HDFS连接信息
    private final static String HDFS_URI = "hdfs://localhost:9000";
    private final static String HDFS_USERNAME = "hdfsuser";
    private final static String HDFS_FILE_PATH = "/path/to/hdfs/file.txt";

    public static void main(String[] args) throws IOException {
        // 创建FTP客户端并连接到FTP服务器
        FTPClient ftpClient = new FTPClient();
        ftpClient.connect(FTP_SERVER);
        ftpClient.login(FTP_USERNAME, FTP_PASSWORD);
        ftpClient.enterLocalPassiveMode();
        ftpClient.setFileType(FTP.BINARY_FILE_TYPE);

        // 获取FTP文件并拷贝到本地
        File localFile = new File(FILE_PATH);
        OutputStream outputStream = new BufferedOutputStream(new FileOutputStream(localFile));
        ftpClient.retrieveFile(FILE_PATH, outputStream);
        outputStream.close();
        ftpClient.logout();

        // 连接到HDFS
        Configuration configuration = new Configuration();
        configuration.set("fs.default.name", HDFS_URI);
        FileSystem hdfs = FileSystem.get(configuration);
        Path hdfsPath = new Path(HDFS_USERNAME, HDFS_FILE_PATH);

        // 将本地文件拷贝到HDFS
        InputStream inputStream = new BufferedInputStream(new FileInputStream(localFile));
        OutputStream outputStreamHdfs = hdfs.create(hdfsPath);
        byte[] buffer = new byte[4096];
        int bytesRead;
        while((bytesRead = inputStream.read(buffer)) != -1) {
            outputStreamHdfs.write(buffer, 0, bytesRead);
        }
        outputStreamHdfs.close();
        hdfs.close();
    }
}

使用FTP协议传输文件到HDFS的示例就完成了。

3.编写代码传输HTTP文件到HDFS

我们可以使用Apache HttpClient库下载HTTP文件，并将其传输到HDFS上。以下是一个示例：

// 引入必要的类
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import java.io.*;

public class HttpToHdfs {
    // HTTP文件下载链接
    private final static String FILE_URL = "http://example.com/file.txt";
    // HDFS连接信息
    private final static String HDFS_URI = "hdfs://localhost:9000";
    private final static String HDFS_USERNAME = "hdfsuser";
    private final static String HDFS_FILE_PATH = "/path/to/hdfs/file.txt";

    public static void main(String[] args) throws IOException {
        // 创建HTTP客户端并下载文件
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet(FILE_URL);
        CloseableHttpResponse httpResponse = httpClient.execute(httpGet);

        // 将HTTP文件拷贝到本地
        HttpEntity httpEntity = httpResponse.getEntity();
        InputStream inputStream = httpEntity.getContent();
        File localFile = new File("localFile.txt");
        OutputStream outputStream = new BufferedOutputStream(new FileOutputStream(localFile));
        byte[] buffer = new byte[4096];
        int bytesRead;
        while((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
        inputStream.close();
        outputStream.close();
        httpResponse.close();
        httpClient.close();

        // 连接到HDFS
        Configuration configuration = new Configuration();
        configuration.set("fs.default.name", HDFS_URI);
        FileSystem hdfs = FileSystem.get(configuration);
        Path hdfsPath = new Path(HDFS_USERNAME, HDFS_FILE_PATH);

        // 将本地文件拷贝到HDFS
        InputStream inputStreamLocal = new BufferedInputStream(new FileInputStream(localFile));
        OutputStream outputStreamHdfs = hdfs.create(hdfsPath);
        while((bytesRead = inputStreamLocal.read(buffer)) != -1) {
            outputStreamHdfs.write(buffer, 0, bytesRead);
        }
        outputStreamHdfs.close();
        hdfs.close();
    }
}

至此，一个示例展示了应该如何将FTP和HTTP文件传输到HDFS。