Hadoop 如何在Java中执行Sqoop？

我创建了一个新的Java项目，然后添加了库Sqoop和Hadoop。（库是“hadoop-core-1.1.1.jar、sqoop-1.4.2.jar等…”

然后我尝试了以下代码：

public class MySqoopDriver {
    public static void main(String[] args) {
        String[] str = { "export", "--connect", "jdbc:mysql://localhost/mytestdb", "--hadoop-home",
                "/home/yoonhok/development/hadoop-1.1.1", "--table", "tbl_1", "--export-dir", "hdfs://localhost:9000/user/hive/warehouse/tbl_1",
                "--username", "yoonhok", "--password", "1234"};

        Sqoop.runTool(str);
    }
}

参数是正确的，因为当我尝试在终端，它工作得很好

但它不起作用。错误消息是：

13/02/17 16:23:07 WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead.
13/02/17 16:23:07 INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset.
13/02/17 16:23:07 INFO tool.CodeGenTool: Beginning code generation
13/02/17 16:23:07 INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `tbl_1` AS t LIMIT 1
13/02/17 16:23:07 INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `tbl_1` AS t LIMIT 1
13/02/17 16:23:07 INFO orm.CompilationManager: HADOOP_HOME is /home/yoonhok/development/hadoop-1.1.1
Note: /tmp/sqoop-yoonhok/compile/86a3cab62184ad50a3ae11e7cb0e4f4d/tbl_1.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
13/02/17 16:23:08 INFO orm.CompilationManager: Writing jar file: /tmp/sqoop-yoonhok/compile/86a3cab62184ad50a3ae11e7cb0e4f4d/tbl_1.jar
13/02/17 16:23:08 INFO mapreduce.ExportJobBase: Beginning export of tbl_1
13/02/17 16:23:09 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
13/02/17 16:23:09 INFO input.FileInputFormat: Total input paths to process : 1
13/02/17 16:23:09 INFO input.FileInputFormat: Total input paths to process : 1
13/02/17 16:23:09 INFO mapred.JobClient: Cleaning up the staging area file:/tmp/hadoop-yoonhok/mapred/staging/yoonhok1526809600/.staging/job_local_0001
13/02/17 16:23:09 ERROR security.UserGroupInformation: PriviledgedActionException as:yoonhok cause:java.io.FileNotFoundException: File /user/hive/warehouse/tbl_1/000000_0 does not exist.
13/02/17 16:23:09 ERROR tool.ExportTool: Encountered IOException running export job: java.io.FileNotFoundException: File /user/hive/warehouse/tbl_1/000000_0 does not exist.

当我检查HDFS时，文件存在：

hadoop fs -ls /user/hive/warehouse/tbl_1
Found 1 items
-rw-r--r--   1 yoonhok supergroup        240 2013-02-16 18:56 /user/hive/warehouse/tbl_1/000000_0

如何在Java程序中执行Sqoop

我尝试了Processbuilder和Process，但我不想使用它们

我真的很想使用sqoopapi，但我听说它还不存在

---

我读过，但它对我不起作用。

首先让我提到，SQOOP1没有官方的客户端API。尽管以您这样的方式调用Sqoop是非常常见和有效的

根据日志，我猜执行Sqoop的java应用程序在类路径上没有hadoop配置。因此，Sqoop不会获取关于集群的信息，而是在“本地”模式下工作。为了在远程集群上运行Sqoop，需要将hadoop配置放入类路径中。有关更多详细信息，请在stackoverflow上签出以下内容。

您可以使用“SqoopOptions”在Java程序中执行sqoop

这是将MySql中的表导入HDFS的示例代码

public static void importSQLToHDFS() throws Exception {
    String driver = "com.mysql.jdbc.Driver";
    Class.forName(driver).newInstance();

    Configuration config = new Configuration(); 
    config.addResource(new Path("/.../conf/core-site.xml"));
    config.addResource(new Path("/.../conf/hdfs-site.xml"));

    properties.load(new FileInputStream("/.../sqoopimport.properties"));

    SqoopOptions options = new SqoopOptions();
    options.setDriverClassName(driver);
    options.setHadoopHome("/.../hadoop-0.20.2-cdh3u2");
    options.setConnectString(properties.getProperty("db_connection_string"));
    options.setTableName(properties.getProperty("db_mysql_table_name"));
    options.setUsername(properties.getProperty("db_usr_id"));
    options.setPassword(properties.getProperty("db_passwd"));
    options.setNumMappers(1);
    options.setTargetDir(properties.getProperty("path_export_file"));
    options.setFileLayout(FileLayout.TextFile);

    new ImportTool().run(options);
}

有关导出，请参见下面的示例代码。 注意：此处不使用属性文件。确保已创建要导入数据的表

public static boolean exportHDFSToSQL() throws InstantiationException, IllegalAccessException, ClassNotFoundException {
    try {
         SqoopOptions options=new SqoopOptions();
         options.setConnectString("jdbc:mysql://localhost:3306/dbName");
         options.setUsername("user_name");
         options.setPassword("pwd");
         options.setExportDir("path of file to be exported from hdfs");
         options.setTableName("table_name");
         options.setInputFieldsTerminatedBy(',');
         options.setNumMappers(1);
         new ExportTool().run(options);
    } catch (Exception e) {
        return false;
    }
    return true;
}

---

有一个技巧对我来说很简单。通过ssh，您可以直接执行Sqoop命令。您只需要使用SSH Java库

你必须遵循这一步

下载sshxcute java库： 并将其添加到包含以下java代码的java项目的构建路径中

import net.neoremind.sshxcute.core.SSHExec;
import net.neoremind.sshxcute.core.ConnBean;
import net.neoremind.sshxcute.task.CustomTask;
import net.neoremind.sshxcute.task.impl.ExecCommand;

public class TestSSH {

   public static void main(String args[]) throws Exception{

    // Initialize a ConnBean object, parameter list is ip, username, password

    ConnBean cb = new ConnBean("192.168.56.102", "root","hadoop");

    // Put the ConnBean instance as parameter for SSHExec static method getInstance(ConnBean) to retrieve a singleton SSHExec instance
    SSHExec ssh = SSHExec.getInstance(cb);          
    // Connect to server
    ssh.connect();
    CustomTask sampleTask1 = new ExecCommand("echo $SSH_CLIENT"); // Print Your Client IP By which you connected to ssh server on Horton Sandbox
    System.out.println(ssh.exec(sampleTask1));
    CustomTask sampleTask2 = new ExecCommand("sqoop import --connect jdbc:mysql://192.168.56.101:3316/mysql_db_name --username=mysql_user --password=mysql_pwd --table mysql_table_name --hive-import -m 1 -- --schema default");
    ssh.exec(sampleTask2);
    ssh.disconnect();   
   }
}

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谢谢你的帮助。但什么是“属性”？我成功了吗？我不知道“/…/sqoopimport.properties”嗯…是的，上面的代码需要创建一个属性文件。上面的代码用于将表从MySQL导入HDFS。对于导出，请使用“新建导出工具（）。运行（选项）；“复制”：