Java hello world
This code sample is a "hello world" application written in Java, using the Bigtable client library for Java. The sample illustrates how to complete the following tasks:
- Set up authentication
- Connect to a Bigtable instance.
- Create a new table.
- Write data to the table.
- Read the data back.
- Delete the table.
Running the sample
This code communicates with Bigtable using the Bigtable client library in the Google Cloud client libraries for Java .
Before you begin, follow the setup steps described in the reference documentation .
Using the Cloud Client Libraries with Bigtable
The sample application connects to Bigtable and demonstrates some basic operations.
Connecting to Bigtable
To get started, you need a data client that you use to communicate with the data API client library and a table admin client that you use to communicate with the admin API client library.
First, instantiate a BigtableDataSettings
object
that includes the project ID and instance ID that the hello world
application
will use. Then pass the settings to the BigtableDataClient.create()
method to create the data client.
Similarly, for the admin client, first establish the settings by creating a BigtableTableAdminSettings
object, then use
the settings to create a BigtableTableAdminClient
object.
As a best practice, when you use Bigtable you should always create a client once and reuse it throughout the application.
// Creates the settings to configure a bigtable data client.
BigtableDataSettings
settings
=
BigtableDataSettings
.
newBuilder
().
setProjectId
(
projectId
).
setInstanceId
(
instanceId
).
build
();
// Creates a bigtable data client.
dataClient
=
BigtableDataClient
.
create
(
settings
);
// Creates the settings to configure a bigtable table admin client.
BigtableTableAdminSettings
adminSettings
=
BigtableTableAdminSettings
.
newBuilder
()
.
setProjectId
(
projectId
)
.
setInstanceId
(
instanceId
)
.
build
();
// Creates a bigtable table admin client.
adminClient
=
BigtableTableAdminClient
.
create
(
adminSettings
);
Creating a table
To create a table, build a CreateTableRequest
object
and pass it to the admin client's createTable()
method.
// Checks if table exists, creates table if does not exist.
if
(
!
adminClient
.
exists
(
tableId
))
{
System
.
out
.
println
(
"Creating table: "
+
tableId
);
CreateTableRequest
createTableRequest
=
CreateTableRequest
.
of
(
tableId
).
addFamily
(
COLUMN_FAMILY
);
adminClient
.
createTable
(
createTableRequest
);
System
.
out
.
printf
(
"Table %s created successfully%n"
,
tableId
);
}
Writing rows to a table
Create a greetings[]
string array containing three greetings, to use as
a source of data to write to the table. Loop through the array. In each
iteration of the loop, create a RowMutation
object and use the setCell()
method to add an entry to the
mutation.
try
{
System
.
out
.
println
(
"\nWriting some greetings to the table"
);
String
[]
names
=
{
"World"
,
"Bigtable"
,
"Java"
};
for
(
int
i
=
0
;
i
<
names
.
length
;
i
++
)
{
String
greeting
=
"Hello "
+
names
[
i
]
+
"!"
;
RowMutation
rowMutation
=
RowMutation
.
create
(
TableId
.
of
(
tableId
),
ROW_KEY_PREFIX
+
i
)
.
setCell
(
COLUMN_FAMILY
,
COLUMN_QUALIFIER_NAME
,
names
[
i
]
)
.
setCell
(
COLUMN_FAMILY
,
COLUMN_QUALIFIER_GREETING
,
greeting
);
dataClient
.
mutateRow
(
rowMutation
);
System
.
out
.
println
(
greeting
);
}
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to write to non-existent table: "
+
e
.
getMessage
());
}
Reading a row by its row key
Use the data client's readRow()
method to read
the first row that you wrote.
try
{
System
.
out
.
println
(
"\nReading a single row by row key"
);
Row
row
=
dataClient
.
readRow
(
TableId
.
of
(
tableId
),
ROW_KEY_PREFIX
+
0
);
System
.
out
.
println
(
"Row: "
+
row
.
getKey
().
toStringUtf8
());
for
(
RowCell
cell
:
row
.
getCells
())
{
System
.
out
.
printf
(
"Family: %s Qualifier: %s Value: %s%n"
,
cell
.
getFamily
(),
cell
.
getQualifier
().
toStringUtf8
(),
cell
.
getValue
().
toStringUtf8
());
}
return
row
;
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to read from a non-existent table: "
+
e
.
getMessage
());
return
null
;
}
try
{
System
.
out
.
println
(
"\nReading specific cells by family and qualifier"
);
Row
row
=
dataClient
.
readRow
(
TableId
.
of
(
tableId
),
ROW_KEY_PREFIX
+
0
);
System
.
out
.
println
(
"Row: "
+
row
.
getKey
().
toStringUtf8
());
List<RowCell>
cells
=
row
.
getCells
(
COLUMN_FAMILY
,
COLUMN_QUALIFIER_NAME
);
for
(
RowCell
cell
:
cells
)
{
System
.
out
.
printf
(
"Family: %s Qualifier: %s Value: %s%n"
,
cell
.
getFamily
(),
cell
.
getQualifier
().
toStringUtf8
(),
cell
.
getValue
().
toStringUtf8
());
}
return
cells
;
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to read from a non-existent table: "
+
e
.
getMessage
());
return
null
;
}
Scanning all table rows
Next, scan the entire table. Create a Query
object, pass it to the readRows()
method, and assign the results to a
row stream.
try
{
System
.
out
.
println
(
"\nReading the entire table"
);
Query
query
=
Query
.
create
(
TableId
.
of
(
tableId
));
ServerStream<Row>
rowStream
=
dataClient
.
readRows
(
query
);
List<Row>
tableRows
=
new
ArrayList
<> ();
for
(
Row
r
:
rowStream
)
{
System
.
out
.
println
(
"Row Key: "
+
r
.
getKey
().
toStringUtf8
());
tableRows
.
add
(
r
);
for
(
RowCell
cell
:
r
.
getCells
())
{
System
.
out
.
printf
(
"Family: %s Qualifier: %s Value: %s%n"
,
cell
.
getFamily
(),
cell
.
getQualifier
().
toStringUtf8
(),
cell
.
getValue
().
toStringUtf8
());
}
}
return
tableRows
;
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to read a non-existent table: "
+
e
.
getMessage
());
return
null
;
}
Deleting a table
Finally, delete the table with the deleteTable()
method.
System
.
out
.
println
(
"\nDeleting table: "
+
tableId
);
try
{
adminClient
.
deleteTable
(
tableId
);
System
.
out
.
printf
(
"Table %s deleted successfully%n"
,
tableId
);
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to delete a non-existent table: "
+
e
.
getMessage
());
}
Putting it all together
Here is the full code sample without comments.
package
com.example.bigtable
;
import static
com.google.cloud.bigtable.data.v2.models. Filters
.FILTERS
;
import
com.google.api.gax.rpc. NotFoundException
;
import
com.google.api.gax.rpc. ServerStream
;
import
com.google.cloud.bigtable.admin.v2. BigtableTableAdminClient
;
import
com.google.cloud.bigtable.admin.v2. BigtableTableAdminSettings
;
import
com.google.cloud.bigtable.admin.v2.models. CreateTableRequest
;
import
com.google.cloud.bigtable.data.v2. BigtableDataClient
;
import
com.google.cloud.bigtable.data.v2. BigtableDataSettings
;
import
com.google.cloud.bigtable.data.v2.models. Filters
.Filter
;
import
com.google.cloud.bigtable.data.v2.models. Query
;
import
com.google.cloud.bigtable.data.v2.models. Row
;
import
com.google.cloud.bigtable.data.v2.models. RowCell
;
import
com.google.cloud.bigtable.data.v2.models. RowMutation
;
import
com.google.cloud.bigtable.data.v2.models. TableId
;
import
java.io.IOException
;
import
java.nio.charset.StandardCharsets
;
import
java.util.ArrayList
;
import
java.util.Base64
;
import
java.util.List
;
public
class
HelloWorld
{
private
static
final
String
COLUMN_FAMILY
=
"cf1"
;
private
static
final
String
COLUMN_QUALIFIER_GREETING
=
"greeting"
;
private
static
final
String
COLUMN_QUALIFIER_NAME
=
"name"
;
private
static
final
String
ROW_KEY_PREFIX
=
"rowKey"
;
private
final
String
tableId
;
private
final
BigtableDataClient
dataClient
;
private
final
BigtableTableAdminClient
adminClient
;
public
static
void
main
(
String
[]
args
)
throws
Exception
{
if
(
args
.
length
!=
2
)
{
System
.
out
.
println
(
"Missing required project id or instance id"
);
return
;
}
String
projectId
=
args
[
0
]
;
String
instanceId
=
args
[
1
]
;
HelloWorld
helloWorld
=
new
HelloWorld
(
projectId
,
instanceId
,
"test-table"
);
helloWorld
.
run
();
}
public
HelloWorld
(
String
projectId
,
String
instanceId
,
String
tableId
)
throws
IOException
{
this
.
tableId
=
tableId
;
BigtableDataSettings
settings
=
BigtableDataSettings
.
newBuilder
().
setProjectId
(
projectId
).
setInstanceId
(
instanceId
).
build
();
dataClient
=
BigtableDataClient
.
create
(
settings
);
BigtableTableAdminSettings
adminSettings
=
BigtableTableAdminSettings
.
newBuilder
()
.
setProjectId
(
projectId
)
.
setInstanceId
(
instanceId
)
.
build
();
adminClient
=
BigtableTableAdminClient
.
create
(
adminSettings
);
}
public
void
run
()
throws
Exception
{
createTable
();
writeToTable
();
readSingleRow
();
readSpecificCells
();
readTable
();
filterLimitCellsPerCol
(
tableId
);
deleteTable
();
close
();
}
public
void
close
()
{
dataClient
.
close
();
adminClient
.
close
();
}
public
void
createTable
()
{
if
(
!
adminClient
.
exists
(
tableId
))
{
System
.
out
.
println
(
"Creating table: "
+
tableId
);
CreateTableRequest
createTableRequest
=
CreateTableRequest
.
of
(
tableId
).
addFamily
(
COLUMN_FAMILY
);
adminClient
.
createTable
(
createTableRequest
);
System
.
out
.
printf
(
"Table %s created successfully%n"
,
tableId
);
}
}
public
void
writeToTable
()
{
try
{
System
.
out
.
println
(
"\nWriting some greetings to the table"
);
String
[]
names
=
{
"World"
,
"Bigtable"
,
"Java"
};
for
(
int
i
=
0
;
i
<
names
.
length
;
i
++
)
{
String
greeting
=
"Hello "
+
names
[
i
]
+
"!"
;
RowMutation
rowMutation
=
RowMutation
.
create
(
TableId
.
of
(
tableId
),
ROW_KEY_PREFIX
+
i
)
.
setCell
(
COLUMN_FAMILY
,
COLUMN_QUALIFIER_NAME
,
names
[
i
]
)
.
setCell
(
COLUMN_FAMILY
,
COLUMN_QUALIFIER_GREETING
,
greeting
);
dataClient
.
mutateRow
(
rowMutation
);
System
.
out
.
println
(
greeting
);
}
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to write to non-existent table: "
+
e
.
getMessage
());
}
}
public
Row
readSingleRow
()
{
try
{
System
.
out
.
println
(
"\nReading a single row by row key"
);
Row
row
=
dataClient
.
readRow
(
TableId
.
of
(
tableId
),
ROW_KEY_PREFIX
+
0
);
System
.
out
.
println
(
"Row: "
+
row
.
getKey
().
toStringUtf8
());
for
(
RowCell
cell
:
row
.
getCells
())
{
System
.
out
.
printf
(
"Family: %s Qualifier: %s Value: %s%n"
,
cell
.
getFamily
(),
cell
.
getQualifier
().
toStringUtf8
(),
cell
.
getValue
().
toStringUtf8
());
}
return
row
;
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to read from a non-existent table: "
+
e
.
getMessage
());
return
null
;
}
}
public
List<RowCell>
readSpecificCells
()
{
try
{
System
.
out
.
println
(
"\nReading specific cells by family and qualifier"
);
Row
row
=
dataClient
.
readRow
(
TableId
.
of
(
tableId
),
ROW_KEY_PREFIX
+
0
);
System
.
out
.
println
(
"Row: "
+
row
.
getKey
().
toStringUtf8
());
List<RowCell>
cells
=
row
.
getCells
(
COLUMN_FAMILY
,
COLUMN_QUALIFIER_NAME
);
for
(
RowCell
cell
:
cells
)
{
System
.
out
.
printf
(
"Family: %s Qualifier: %s Value: %s%n"
,
cell
.
getFamily
(),
cell
.
getQualifier
().
toStringUtf8
(),
cell
.
getValue
().
toStringUtf8
());
}
return
cells
;
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to read from a non-existent table: "
+
e
.
getMessage
());
return
null
;
}
}
public
List<Row>
readTable
()
{
try
{
System
.
out
.
println
(
"\nReading the entire table"
);
Query
query
=
Query
.
create
(
TableId
.
of
(
tableId
));
ServerStream<Row>
rowStream
=
dataClient
.
readRows
(
query
);
List<Row>
tableRows
=
new
ArrayList
<> ();
for
(
Row
r
:
rowStream
)
{
System
.
out
.
println
(
"Row Key: "
+
r
.
getKey
().
toStringUtf8
());
tableRows
.
add
(
r
);
for
(
RowCell
cell
:
r
.
getCells
())
{
System
.
out
.
printf
(
"Family: %s Qualifier: %s Value: %s%n"
,
cell
.
getFamily
(),
cell
.
getQualifier
().
toStringUtf8
(),
cell
.
getValue
().
toStringUtf8
());
}
}
return
tableRows
;
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to read a non-existent table: "
+
e
.
getMessage
());
return
null
;
}
}
public
void
filterLimitCellsPerCol
(
String
tableId
)
{
Filter
filter
=
FILTERS
.
limit
().
cellsPerColumn
(
1
);
readRowFilter
(
tableId
,
filter
);
readFilter
(
tableId
,
filter
);
}
private
void
readRowFilter
(
String
tableId
,
Filter
filter
)
{
String
rowKey
=
Base64
.
getEncoder
().
encodeToString
(
"greeting0"
.
getBytes
(
StandardCharsets
.
UTF_8
));
Row
row
=
dataClient
.
readRow
(
TableId
.
of
(
tableId
),
rowKey
,
filter
);
printRow
(
row
);
System
.
out
.
println
(
"Row filter completed."
);
}
private
void
readFilter
(
String
tableId
,
Filter
filter
)
{
Query
query
=
Query
.
create
(
TableId
.
of
(
tableId
)).
filter
(
filter
);
ServerStream<Row>
rows
=
dataClient
.
readRows
(
query
);
for
(
Row
row
:
rows
)
{
printRow
(
row
);
}
System
.
out
.
println
(
"Table filter completed."
);
}
public
void
deleteTable
()
{
System
.
out
.
println
(
"\nDeleting table: "
+
tableId
);
try
{
adminClient
.
deleteTable
(
tableId
);
System
.
out
.
printf
(
"Table %s deleted successfully%n"
,
tableId
);
}
catch
(
NotFoundException
e
)
{
System
.
err
.
println
(
"Failed to delete a non-existent table: "
+
e
.
getMessage
());
}
}
private
static
void
printRow
(
Row
row
)
{
if
(
row
==
null
)
{
return
;
}
System
.
out
.
printf
(
"Reading data for %s%n"
,
row
.
getKey
().
toStringUtf8
());
String
colFamily
=
""
;
for
(
RowCell
cell
:
row
.
getCells
())
{
if
(
!
cell
.
getFamily
().
equals
(
colFamily
))
{
colFamily
=
cell
.
getFamily
();
System
.
out
.
printf
(
"Column Family %s%n"
,
colFamily
);
}
String
labels
=
cell
.
getLabels
().
size
()
==
0
?
""
:
" ["
+
String
.
join
(
","
,
cell
.
getLabels
())
+
"]"
;
System
.
out
.
printf
(
"\t%s: %s @%s%s%n"
,
cell
.
getQualifier
().
toStringUtf8
(),
cell
.
getValue
().
toStringUtf8
(),
cell
.
getTimestamp
(),
labels
);
}
System
.
out
.
println
();
}
}
