如何从Hbase读取数据？ [英] How to read data from Hbase?

问题描述

您好，我用于SQL，但我需要从HBase表中读取数据。任何对此的帮助都会很大。一本书或者可能只是一些示例代码来从表中读取。有人说使用扫描仪可以做到这一点，但我不知道如何使用它。 解决方案

From 网站：

  //有时，您不会知道您要查找的行。在这种情况下，您
 //使用扫描仪。这会给你表格的内容
 //的游标式界面。要设置一个扫描仪，像上面做的那样做一个Put 
 //一个Get，创建一个扫描。用列名等来装饰它
 Scan s = new Scan（）; 
 s.addColumn（Bytes.toBytes（myLittleFamily），Bytes.toBytes（someQualifier））; 
 ResultScanner scanner = table.getScanner（s）; 
尝试{
 //扫描仪返回结果实例。 
 //现在，对于实际的迭代。一种方法是使用如下所示的while循环：
 for（Result rr = scanner.next（）; rr！= null; rr = scanner.next（））{
 //输出行我们发现和我们寻找的列
 System.out.println（Found row：+ rr）; 
} 
 
 //另一种方法是使用foreach循环。扫描仪是可迭代的！ 
 // for（Result rr：scanner）{
 // System.out.println（Found row：+ rr）; 
 //} 
}最后{
 //确保您完成后关闭扫描仪！ 
 //这就是为什么我们把它放在try / finally子句中
 scanner.close（）; 
} 
  

Hi there I'm use to SQL, but I need to read data from a HBase table. Any help on this would be great. A book or maybe just some sample code to read from the table. Someone said using a scanner would do the trick, but I do not know how to use it.

解决方案

From the website:

// Sometimes, you won't know the row you're looking for. In this case, you
// use a Scanner. This will give you cursor-like interface to the contents
// of the table.  To set up a Scanner, do like you did above making a Put
// and a Get, create a Scan.  Adorn it with column names, etc.
Scan s = new Scan();
s.addColumn(Bytes.toBytes("myLittleFamily"), Bytes.toBytes("someQualifier"));
ResultScanner scanner = table.getScanner(s);
try {
  // Scanners return Result instances.
  // Now, for the actual iteration. One way is to use a while loop like so:
  for (Result rr = scanner.next(); rr != null; rr = scanner.next()) {
    // print out the row we found and the columns we were looking for
    System.out.println("Found row: " + rr);
  }

  // The other approach is to use a foreach loop. Scanners are iterable!
  // for (Result rr : scanner) {
  //   System.out.println("Found row: " + rr);
  // }
} finally {
  // Make sure you close your scanners when you are done!
  // Thats why we have it inside a try/finally clause
  scanner.close();
}

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