Sqoop Java API 导入应用案例
环境信息：
Linux+JDK1.7
Sqoop 1.4.6-cdh5.5.2
hadoop-core 2.6.0-mr1-cdh5.5.2
hadoop-common 2.6.0-cdh5.5.2
hadoop-mapreduce-client-core 2.6.0-cdh5.5.2
需求：
将oracle中的某表导入到hdfs
实现：
首先组织Sqoop命令：
String[] args = new String[] { // Oracle数据库信息 "--connect","jdbc:oracle:thin:@***:1522/**", "-username","***", "-password","***",
// 查询sql "--query","select * from TABLE_NAME where $CONDITIONS and create_date>=date'2017-05-01' and create_date<date'2017-06-01' ", "-split-by","id", "--hive-overwrite", "--fields-terminated-by","'\\001'", "--hive-drop-import-delims", "--null-string","'\\\\N'", "--null-non-string","'\\\\N'", "--verbose", "--target-dir","/user/hive/warehouse/test.db/H_TABLE_NAME" };
执行Sqoop任务：
String[] expandArguments = OptionsFileUtil.expandArguments(args); SqoopTool tool = SqoopTool.getTool("import"); Configuration conf = new Configuration(); conf.set("fs.default.name", "hdfs://nameservice1");//设置HDFS服务地址 Configuration loadPlugins = SqoopTool.loadPlugins(conf); Sqoop sqoop = new Sqoop((com.cloudera.sqoop.tool.SqoopTool) tool, loadPlugins); int res = Sqoop.runSqoop(sqoop, expandArguments); if (res == 0) log.info ("成功");
完成编码后，发到测试环境进行测试，发现Sqoop在进行动态编译时报编译错误：
2017-07-26 15:10:15 [ERROR] [http-0.0.0.0-8080-6] [org.apache.sqoop.tool.ImportTool.run(ImportTool.java:613)] Encountered IOException running import job: java.io.IOException: Error returned by javac
at org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:217)
at org.apache.sqoop.tool.CodeGenTool.generateORM(CodeGenTool.java:108)
at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:478)
at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:605)
at org.apache.sqoop.Sqoop.run(Sqoop.java:143)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:179)
动态编译的日志如果没有特殊配置的话，是无法通过log4j进行输出的，因此，编译错误需要到系统日志里查找：
/tmp/sqoop-deploy/compile/b78440d7bc7097805be8b088c525566b/QueryResult.java:7: error: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.BytesWritable;
^
/tmp/sqoop-deploy/compile/b78440d7bc7097805be8b088c525566b/QueryResult.java:8: error: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.Text;
^
/tmp/sqoop-deploy/compile/b78440d7bc7097805be8b088c525566b/QueryResult.java:9: error: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.Writable;
^
/tmp/sqoop-deploy/compile/b78440d7bc7097805be8b088c525566b/QueryResult.java:37: error: cannot access Writable
public class QueryResult extends SqoopRecord implements DBWritable, Writable {
如上，推测是动态编译环境的classpath没有包含hadoop-common包导致的，在CompilationManager里查到了如下内容：
private String findHadoopJars() { String hadoopMapRedHome = options.getHadoopMapRedHome(); if (null == hadoopMapRedHome) { LOG.info("$HADOOP_MAPRED_HOME is not set"); return Jars.getJarPathForClass(JobConf.class); } if (!hadoopMapRedHome.endsWith(File.separator)) { hadoopMapRedHome = hadoopMapRedHome + File.separator; } File hadoopMapRedHomeFile = new File(hadoopMapRedHome); LOG.info("HADOOP_MAPRED_HOME is " + hadoopMapRedHomeFile.getAbsolutePath()); Iterator<File> filesIterator = FileUtils.iterateFiles(hadoopMapRedHomeFile, new String[] { "jar" }, true); StringBuilder sb = new StringBuilder(); while (filesIterator.hasNext()) { File file = filesIterator.next(); String name = file.getName(); if (name.startsWith("hadoop-common") || name.startsWith("hadoop-mapreduce-client-core") || name.startsWith("hadoop-core")) { sb.append(file.getAbsolutePath()); sb.append(File.pathSeparator); } } if (sb.length() < 1) { LOG.warn("HADOOP_MAPRED_HOME appears empty or missing"); return Jars.getJarPathForClass(JobConf.class); } String s = sb.substring(0, sb.length() - 1); LOG.debug("Returning jar file path " + s); return s; }
推测是由于配置里没有hadoopMapRedHome这个参数，导致这个方法只能取到JobConf.class所在的jar包，即hadoop-core包。打开DEBUG进行验证，找到如下日志：
2017-07-26 15:10:14 [INFO] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.findHadoopJars(CompilationManager.java:85)] $HADOOP_MAPRED_HOME is not set
2017-07-26 15:10:14 [DEBUG] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:171)] Current sqoop classpath = :/usr/local/tomcat6/bin/bootstrap.jar
2017-07-26 15:10:14 [DEBUG] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:195)] Adding source file: /tmp/sqoop-deploy/compile/1baf2f947722b9531d4a27b1e5ef5aca/QueryResult.java
2017-07-26 15:10:14 [DEBUG] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:199)] Invoking javac with args:
2017-07-26 15:10:14 [DEBUG] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:201)] -sourcepath
2017-07-26 15:10:14 [DEBUG] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:201)] /tmp/sqoop-deploy/compile/1baf2f947722b9531d4a27b1e5ef5aca/
2017-07-26 15:10:14 [DEBUG] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:201)] -d
2017-07-26 15:10:14 [DEBUG] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:201)] /tmp/sqoop-deploy/compile/1baf2f947722b9531d4a27b1e5ef5aca/
2017-07-26 15:10:14 [DEBUG] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:201)] -classpath
2017-07-26 15:10:14 [DEBUG] [http-0.0.0.0-8080-6] [org.apache.sqoop.orm.CompilationManager.compile(CompilationManager.java:201)] :/usr/local/tomcat6/bin/bootstrap.jar:/var/www/webapps/***/WEB-INF/lib/hadoop-core-2.6.0-mr1-cdh5.5.2.jar:/var/www/webapps/***/WEB-INF/lib/sqoop-1.4.6-cdh5.5.2.jar
果然是缺少了jar包。在CompilationManager中查到classpath的组装方式如下：
String curClasspath = System.getProperty("java.class.path");
LOG.debug("Current sqoop classpath = " + curClasspath);
args.add("-sourcepath");
args.add(jarOutDir);
args.add("-d");
args.add(jarOutDir);
args.add("-classpath");
args.add(curClasspath + File.pathSeparator + coreJar + sqoopJar);
可以通过两种方式将缺失的jar添加进去：
1.直接修改java.class.path：
String curClasspath = System.getProperty ("java.class.path");
curClasspath = curClasspath
+ File.pathSeparator
+ "/var/www/webapps/***/WEB-INF/lib/hadoop-common-2.6.0-cdh5.5.2.jar"
+ File.pathSeparator
+ "/var/www/webapps/***/WEB-INF/lib/hadoop-mapreduce-client-core-2.6.0-cdh5.5.2.jar";
System.setProperty ("java.class.path", curClasspath);
2.增加配置项（未尝试）：
--hadoop-mapred-home <dir> 指定$HADOOP_MAPRED_HOME路径
使用第一种方式后，已经能够正常进行导入操作：
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.JobClient.monitorAndPrintJob(JobClient.java:1547)] Job complete: job_local703153215_0001
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:566)] Counters: 18
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:568)] File System Counters
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] FILE: Number of bytes read=15015144
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] FILE: Number of bytes written=15688984
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] FILE: Number of read operations=0
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] FILE: Number of large read operations=0
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] FILE: Number of write operations=0
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] HDFS: Number of bytes read=0
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] HDFS: Number of bytes written=1536330810
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] HDFS: Number of read operations=40
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] HDFS: Number of large read operations=0
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] HDFS: Number of write operations=36
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:568)] Map-Reduce Framework
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] Map input records=3272909
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] Map output records=3272909
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] Input split bytes=455
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] Spilled Records=0
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] CPU time spent (ms)=0
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] Physical memory (bytes) snapshot=0
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] Virtual memory (bytes) snapshot=0
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.hadoop.mapred.Counters.log(Counters.java:570)] Total committed heap usage (bytes)=4080271360
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.sqoop.mapreduce.ImportJobBase.runJob(ImportJobBase.java:184)] Transferred 1.4308 GB in 71.5332 seconds (20.4822 MB/sec)
2017-07-26 15:52:00 [INFO] [http-0.0.0.0-8080-1] [org.apache.sqoop.mapreduce.ImportJobBase.runJob(ImportJobBase.java:186)] Retrieved 3272909 records.
至此，Sqoop Java API 导入demo完成。
参考文章：
http://shiyanjun.cn/archives/624.html Sqoop-1.4.4工具import和export使用详解
http://blog.csdn.net/sl1992/article/details/53521819 Java操作Sqoop对象
