文章目录
一、几个主要的HBase API类和数据模型之间的对应关系
二、使用java代码操作HBase
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.*;
import org.apache.hadoop.hbase.util.Bytes;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
1、初始化连接
public class HBaseAPI {
Connection conn;
TableName table = TableName.valueOf("test_cre");
@Before
public void init() throws IOException {
Configuration conf = HBaseConfiguration.create();
conf.set("hbase.zookeeper.quorum","node1,node2,master");
//获取连接
conn = ConnectionFactory.createConnection(conf);
}
2、创建表
@Test
public void create() throws IOException {
Admin admin = conn.getAdmin();
if (!admin.tableExists(TableName.valueOf("test_cre"))){
//创建一个表结构
HTableDescriptor test_cre = new HTableDescriptor(TableName.valueOf("test_cre"));
//创建一个列簇
HColumnDescriptor cf1 = new HColumnDescriptor("cf1");
//设置版本
cf1.setMaxVersions(3);
//设置过期时间
cf1.setTimeToLive(1000);
test_cre.addFamily(cf1);
admin.createTable(test_cre);
}else{
System.out.println("表已存在");
}
}
3、删除表
@Test
public void deleteTable() throws IOException {
Admin admin = conn.getAdmin();
if (admin.tableExists(TableName.valueOf("test_cre"))){
admin.disableTable(TableName.valueOf("test_cre"));
admin.deleteTable(TableName.valueOf("test_cre"));
}else{
System.out.println("表不存在");
}
}
4、修改表
@Test
public void alterTable() throws IOException {
Admin admin = conn.getAdmin();
//获取表的原有结构
HTableDescriptor tableDescriptor = admin.getTableDescriptor(table);
//获取所有列簇构成的HColumnDescriptor数组
HColumnDescriptor[] columnFamilies = tableDescriptor.getColumnFamilies();
//遍历所有的列簇
for (HColumnDescriptor columnFamily : columnFamilies) {
//获取列簇的名称
String cfName = columnFamily.getNameAsString();
//对名字为cf1的列簇进行修改
if ("cf1".equals(cfName)){
columnFamily.setTimeToLive(10000);
}
//修改表结构(modifyTable)
admin.modifyTable(table,tableDescriptor);
}
}
5、添加数据put
@Test
public void Put() throws IOException {
Table test_cre = conn.getTable(table);
Put put = new Put(“001”.getBytes());
put.addColumn(“cf1”.getBytes(),“name”.getBytes(),“zhangsan”.getBytes());
test_cre.put(put);
}
6、putall 读取students.txt 并将数据写入Hbase
@Test
public void PutAll() throws IOException {
//创建表
Admin admin = conn.getAdmin();
TableName studentsT = TableName.valueOf("students");
//判断表是否存在
if (!admin.tableExists(studentsT)){
//创建表结构
HTableDescriptor students = new HTableDescriptor(studentsT);
//创建一个列簇
HColumnDescriptor info = new HColumnDescriptor("info");
//添加列簇
students.addFamily(info);
admin.createTable(students);
}
//向表中添加数据
Table stu = conn.getTable(studentsT);
//读取一个文本文件
BufferedReader br = new BufferedReader(new FileReader("D:\\bigdata\\ownbigdata\\data\\students.txt"));
String line = null;
while((line=br.readLine())!=null){
//读取每一行数据以 ，切分
String[] split = line.split(",");
String id = split[0];
String name = split[1];
String age = split[2];
String sex = split[3];
String clazz = split[4];
Put put = new Put(id.getBytes());
put.addColumn("info".getBytes(),"name".getBytes(),name.getBytes());
put.addColumn("info".getBytes(),"age".getBytes(),age.getBytes());
put.addColumn("info".getBytes(),"sex".getBytes(),sex.getBytes());
put.addColumn("info".getBytes(),"clazz".getBytes(),clazz.getBytes());
stu.put(put);
}
}
6、获取数据
@Test
public void Get() throws IOException {
Table test_cre = conn.getTable(this.table);
Get get = new Get("001".getBytes());
Result result = test_cre.get(get);
byte[] value = result.getValue("cf1".getBytes(), "name".getBytes());
System.out.println(Bytes.toString(value));
}
7、查询数据
@Test
public void Scan() throws IOException {
Table stu = conn.getTable(TableName.valueOf("students"));
Scan scan = new Scan();
// scan.setLimit(5);
scan.withStartRow("1500100010".getBytes());
scan.withStopRow("1500100020".getBytes());
ResultScanner sc = stu.getScanner(scan);
for (Result result : sc) {
String id = Bytes.toString(result.getRow());
String name = Bytes.toString(result.getValue("info".getBytes(), "name".getBytes()));
String age = Bytes.toString(result.getValue("info".getBytes(), "age".getBytes()));
String sex = Bytes.toString(result.getValue("info".getBytes(), "sex".getBytes()));
String clazz = Bytes.toString(result.getValue("info".getBytes(), "clazz".getBytes()));
System.out.println(id + "," + name + "," + age + "," + sex + "," + clazz);
}
}
8、获取数据第二种方式
//适用于每条数据结构不唯一的情况下，直接遍历每条数据包含的所有的cell
@Test
public void scanWithUtil() throws IOException {
Table students = conn.getTable(TableName.valueOf("students"));
Scan scan = new Scan();
// scan.setLimit(5);
scan.withStartRow("1500100010".getBytes());
scan.withStopRow("1500100020".getBytes());
ResultScanner sc = students.getScanner(scan);
for (Result result : sc) {
//通过获取的一条数据去获取每一列的单元格
for (Cell cell : result.listCells()) {
String value = Bytes.toString(CellUtil.cloneValue(cell));
//列名
String qua = Bytes.toString(CellUtil.cloneQualifier(cell));
//列簇名
String cf = Bytes.toString(CellUtil.cloneFamily(cell));
if("age".equals(qua)){
if (Integer.parseInt(value)>=18){
value ="成年";
}else{
value ="未成年";
}
}
System.out.print(value+" ");
}
System.out.println();
}
}
9、关闭连接
@After
public void close() throws IOException {
conn.close();
}
}