Java从FTP服务器中获取PDF文件数据

Java 直接读取本地磁盘的PDF文件很容易，但是要从FTP中获取文件数据缺需要使用工具来连接到FTP服务器，之后才能从中获取到相应的文件数据

操作系统类型：windows

开发工具： idea

项目管理：maven

需要的jar包

<!-- commons jar -->
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-lang3</artifactId>
      <version>3.3.2</version>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.4</version>
    </dependency>
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-collections4</artifactId>
      <version>4.0</version>
    </dependency>
    <dependency>
      <groupId>commons-logging</groupId>
      <artifactId>commons-logging</artifactId>
      <version>1.1.3</version>
    </dependency>
    <dependency>
      <groupId>commons-codec</groupId>
      <artifactId>commons-codec</artifactId>
      <version>1.8</version>
    </dependency>
    <dependency>
      <groupId>commons-beanutils</groupId>
      <artifactId>commons-beanutils</artifactId>
      <version>1.8.3</version>
    </dependency>
    <dependency>
      <groupId>commons-chain</groupId>
      <artifactId>commons-chain</artifactId>
      <version>1.2</version>
    </dependency>
    <dependency>
      <groupId>commons-fileupload</groupId>
      <artifactId>commons-fileupload</artifactId>
      <version>1.3.1</version>
    </dependency>
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-math3</artifactId>
      <version>3.3</version>
    </dependency>
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-pool2</artifactId>
      <version>2.2</version>
    </dependency>
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-digester3</artifactId>
      <version>3.2</version>
    </dependency>
    <dependency>
      <groupId>commons-net</groupId>
      <artifactId>commons-net</artifactId>
      <version>3.3</version>
    </dependency>
    <dependency>
      <groupId>commons-dbutils</groupId>
      <artifactId>commons-dbutils</artifactId>
      <version>1.5</version>
    </dependency>
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-email</artifactId>
      <version>1.3.3</version>
    </dependency>
    <dependency>
      <groupId>commons-dbcp</groupId>
      <artifactId>commons-dbcp</artifactId>
      <version>1.4</version>
    </dependency>

执行程序

import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;

import java.io.IOException;
import java.io.InputStream;
/**
 * Created with CosmosRay
 *
 * @author CosmosRay
 * @date 2019/6/12
 * Function:
 */
public class PDFTest {
    public static void main(String[] args) {
        //FTP服务器的IP
        String ftpIp = "192.168.19.129";
        //FTP服务器的端口
        Integer ftpPort = 21;
        //FTP服务器的用户名
        String ftpName = "admin";
        //FTP服务器的密码
        String ftpPass = "admin";
        //在FTP服务器中改查询的文件所在目录
        String ftpDocument = "/";

        byte[] b = new byte[512];
        //文件名称
        String fileName = "650000.pdf";

        /**
         *  登录ftp，获取事件
         *  这里是ip，用户名，密码
         */
        FTPClient ftp = PDFTest.ftp(ftpIp, ftpPort, ftpName, ftpPass);
        if (null != ftp) {
            try {
                // 更改当前工作目录为文件所在的目录
                ftp.enterLocalPassiveMode();
                ftp.changeWorkingDirectory(ftpDocument);
                // 从ftp上获取pdf目录下的文件
//                FTPFile[] file = ftp.listFiles();
                // 遍历所有文件，匹配需要查找的文件
                int status = ftp.getReplyCode();
                System.out.println("FTP status = " + status);
                // 通过文件名称匹配到的文件流传入接口，转化成数组集合
                InputStream in = ftp.retrieveFileStream(fileName);
                int n = 0;
                while ((n = in.read(b)) != -1) {
                    System.out.println("n  =  =:" + n);
//                    out.write(b, 0, n);
                }
                //将字节流传往jsp
//                out.flush();
//                in.close();
//                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 功能描述
     *
     * @return org.apache.commons.net.ftp.FTPClient
     * @author CosmosRay
     * @date 2019/6/12
     */
    private static FTPClient ftp(String ip, int port, String user, String password) {
        FTPClient ftpClient = new FTPClient();
        try {
            //连接服务器登录服务器
            ftpClient.connect(ip, port);
            ftpClient.login(user, password);
            ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
            // 是否成功登录服务器
            int replyCode = ftpClient.getReplyCode();
            if (!FTPReply.isPositiveCompletion(replyCode)) {
                System.out.println("connect failed...ftp:" + ip);
            } else {
                System.out.println("connect successfu...ftp:" + ip);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        if (!ftpClient.isConnected()) {
            ftpClient = null;
        }
        return ftpClient;
    }
}

输入内容

connect successfu...ftp服务器:192.168.19.129
FTP status = 250