两天前，我在实习中开始学习 Cassandra，他们给了我一个关于 Cassandra 的学习，我从网上找到了一些代码。代码语法上没有错误，但是当我运行代码时，我收到如下错误：
InvalidRequestException（为什么：Keyspace
此架构中不存在博客。）
在
org.apache.cassandra.thrift.Cassandra$remove_result.read(Cassandra.java:14354)
在
org.apache.cassandra.thrift.Cassandra$Client.recv_remove(Cassandra.java:755)
在
org.apache.cassandra.thrift.Cassandra$Client.remove(Cassandra.java:729)
在
Authors.removeAuthor(Authors.java:141)
在 Authors.main(Authors.java:59)
我还使用 ./cassandra -f 命令从控制台运行 cassandra。
我想我需要先建立一个 cassandra 数据库，但我真的找不到如何用 java 来做到这一点。
请帮助我了解这个主题。
非常感谢。
如果有帮助的话，我正在尝试的代码就在这里。
/**
* Sample code for the blog posting:
*
* Installing and using Apache Cassandra With Java Part 4 (Thrift Client)
* http://www.sodeso.nl/?p=251
*
* Please report any discrepancies that you may find,
* if you have any requests for examples not mentioned here
* but are within the scope of the blog posting then also
* please let me know so i can add them..
*/
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.cassandra.thrift.Cassandra;
import org.apache.cassandra.thrift.Column;
import org.apache.cassandra.thrift.ColumnOrSuperColumn;
import org.apache.cassandra.thrift.ColumnParent;
import org.apache.cassandra.thrift.ColumnPath;
import org.apache.cassandra.thrift.ConsistencyLevel;
import org.apache.cassandra.thrift.Deletion;
import org.apache.cassandra.thrift.InvalidRequestException;
import org.apache.cassandra.thrift.KeyRange;
import org.apache.cassandra.thrift.KeySlice;
import org.apache.cassandra.thrift.Mutation;
import org.apache.cassandra.thrift.NotFoundException;
import org.apache.cassandra.thrift.SlicePredicate;
import org.apache.cassandra.thrift.SliceRange;
import org.apache.cassandra.thrift.TimedOutException;
import org.apache.cassandra.thrift.UnavailableException;
import org.apache.thrift.TException;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.transport.TSocket;
import org.apache.thrift.transport.TTransport;
import org.apache.thrift.transport.TTransportException;
/**
* @author Ronald Mathies
*/
public class Authors {
private static final String KEYSPACE = "Blog";
private static final String COLUMN_FAMILY = "Authors";
public static final String ENCODING = "utf-8";
private static TTransport tr = null;
public static void main(String[] args) throws TException, InvalidRequestException, UnavailableException, UnsupportedEncodingException, NotFoundException, TimedOutException {
Cassandra.Client client = setupConnection();
System.out.println("Remove all the authors we might have created before.\n");
removeAuthor(client, "Eric Long");
removeAuthor(client, "Ronald Mathies");
removeAuthor(client, "John Steward");
System.out.println("Create the authors.\n");
createAuthor(client, "Eric Long", "eric (at) long.com", "United Kingdom", "01/01/2002");
createAuthor(client, "Ronald Mathies", "ronald (at) sodeso.nl", "Netherlands, The", "01/01/2010");
createAuthor(client, "John Steward", "john.steward (at) somedomain.com", "Australia", "01/01/2009");
System.out.println("Select Eric Long.\n");
selectSingleAuthorWithAllColumns(client, "Eric Long");
System.out.println("Select Ronald Mathies.\n");
selectSingleAuthorWithAllColumns(client, "Ronald Mathies");
System.out.println("Select John Steward.\n");
selectSingleAuthorWithAllColumns(client, "John Steward");
System.out.println("Select all authors with all columns.\n");
selectAllAuthorsWithAllColumns(client);
System.out.println("Select all authors with only the email column.\n");
selectAllAuthorsWithOnlyTheEmailColumn(client);
System.out.println("Update John Steward.\n");
updateJohnStewardAuthor(client);
System.out.println("Select John Steward.\n");
selectSingleAuthorWithAllColumns(client, "John Steward");
System.out.println("Remove email address and birthday from John Steward.\n");
deleteEmailAndBirthdayFromJohnSteward(client);
System.out.println("Select John Steward.\n");
selectSingleAuthorWithAllColumns(client, "John Steward");
closeConnection();
}
/**
* Open up a new connection to the Cassandra Database.
*
* @return the Cassandra Client
*/
private static Cassandra.Client setupConnection() throws TTransportException {
try {
tr = new TSocket("localhost", 9160);
TProtocol proto = new TBinaryProtocol(tr);
Cassandra.Client client = new Cassandra.Client(proto);
tr.open();
return client;
} catch (TTransportException exception) {
exception.printStackTrace();
}
return null;
}
/**
* Close the connection to the Cassandra Database.
*/
private static void closeConnection() {
try {
tr.flush();
tr.close();
} catch (TTransportException exception) {
exception.printStackTrace();
}
}
/**
* Removes an Author from the Authors ColumnFamily.
* cccc
* @param client the Corg.apache.thrift;
importassandra Client
* @param authorKey The key of the Author
*/
private static void removeAuthor(Cassandra.Client client, String authorKey) {
try {
ColumnPath columnPath = new ColumnPath(COLUMN_FAMILY);
client.remove(KEYSPACE, authorKey, columnPath, System.currentTimeMillis(), ConsistencyLevel.ALL);
} catch (Exception exception) {
exception.printStackTrace();
}
}
/**
* Creates and stores an Author in the Cassandra Database.
*
* @param client the Cassandra Client
* @param authorKey The key of the Author
* @param email the email address
* @param country the country
* @param registeredSince the registration date
*/
private static void createAuthor(Cassandra.Client client, String authorKey, String email, String country, String registeredSince) {
try {
long timestamp = System.currentTimeMillis();
Map<String, List<ColumnOrSuperColumn>> job = new HashMap<String, List<ColumnOrSuperColumn>>();
List<ColumnOrSuperColumn> columns = new ArrayList<ColumnOrSuperColumn>();
Column column = new Column("email".getBytes(ENCODING), email.getBytes(ENCODING), timestamp);
ColumnOrSuperColumn columnOrSuperColumn = new ColumnOrSuperColumn();
columnOrSuperColumn.setColumn(column);
columns.add(columnOrSuperColumn);
column = new Column("country".getBytes(ENCODING), country.getBytes(ENCODING), timestamp);
columnOrSuperColumn = new ColumnOrSuperColumn();
columnOrSuperColumn.setColumn(column);
columns.add(columnOrSuperColumn);
column = new Column("country".getBytes(ENCODING), country.getBytes(ENCODING), timestamp);
columnOrSuperColumn = new ColumnOrSuperColumn();
columnOrSuperColumn.setColumn(column);
columns.add(columnOrSuperColumn);
column = new Column("registeredSince".getBytes(ENCODING), registeredSince.getBytes(ENCODING), timestamp);
columnOrSuperColumn = new ColumnOrSuperColumn();
columnOrSuperColumn.setColumn(column);
columns.add(columnOrSuperColumn);
job.put(COLUMN_FAMILY, columns);
client.batch_insert(KEYSPACE, authorKey, job, ConsistencyLevel.ALL);
} catch (Exception exception) {
exception.printStackTrace();
}
}
/**
* Selects a single author with all the columns from the Cassandra database
* and display it in the console.
*
* @param client the Cassandra client
* @param authorKey The key of the Author
*/
private static void selectSingleAuthorWithAllColumns(Cassandra.Client client, String authorKey) {
try {
SlicePredicate slicePredicate = new SlicePredicate();
SliceRange sliceRange = new SliceRange();
sliceRange.setStart(new byte[] {});
sliceRange.setFinish(new byte[] {});
slicePredicate.setSlice_range(sliceRange);
ColumnParent columnParent = new ColumnParent(COLUMN_FAMILY);
List<ColumnOrSuperColumn> result = client.get_slice(KEYSPACE, authorKey, columnParent, slicePredicate, ConsistencyLevel.ONE);
printToConsole(authorKey, result);
} catch (Exception exception) {
exception.printStackTrace();
}
}
/**
* Selects all the authors with all the columns from the Cassandra database.
*
* @param client the Cassandra client
*/
private static void selectAllAuthorsWithAllColumns(Cassandra.Client client) {
try {
KeyRange keyRange = new KeyRange(3);
keyRange.setStart_key("");
keyRange.setEnd_key("");
SliceRange sliceRange = new SliceRange();
sliceRange.setStart(new byte[] {});
sliceRange.setFinish(new byte[] {});
SlicePredicate slicePredicate = new SlicePredicate();
slicePredicate.setSlice_range(sliceRange);
ColumnParent columnParent = new ColumnParent(COLUMN_FAMILY);
List<KeySlice> keySlices = client.get_range_slices(KEYSPACE, columnParent, slicePredicate, keyRange, ConsistencyLevel.ONE);
for (KeySlice keySlice : keySlices) {
printToConsole(keySlice.getKey(), keySlice.getColumns());
}
} catch (Exception exception) {
exception.printStackTrace();
}
}
/**
* Selects all the authors with only the email column from the Cassandra
* database.
*
* @param client the Cassandra client
*/
private static void selectAllAuthorsWithOnlyTheEmailColumn(Cassandra.Client client) {
try {
KeyRange keyRange = new KeyRange(3);
keyRange.setStart_key("");
keyRange.setEnd_key("");
List<byte[]> columns = new ArrayList<byte[]>();
columns.add("email".getBytes(ENCODING));
SlicePredicate slicePredicate = new SlicePredicate();
slicePredicate.setColumn_names(columns);
ColumnParent columnParent = new ColumnParent(COLUMN_FAMILY);
List<KeySlice> keySlices = client.get_range_slices(KEYSPACE, columnParent, slicePredicate, keyRange, ConsistencyLevel.ONE);
for (KeySlice keySlice : keySlices) {
printToConsole(keySlice.getKey(), keySlice.getColumns());
}
} catch (Exception exception) {
exception.printStackTrace();
}
}
/**
* Update the John Steward author with a new email address and a new field, the birthday.
*
* @param client the Cassandra client
*/
private static void updateJohnStewardAuthor(Cassandra.Client client) {
try {
long timestamp = System.currentTimeMillis();
Map<String, Map<String, List<Mutation>>> job = new HashMap<String, Map<String, List<Mutation>>>();
List<Mutation> mutations = new ArrayList<Mutation>();
// Change the email address
Column column = new Column("email".getBytes(ENCODING), "[email protected]".getBytes(ENCODING), timestamp);
ColumnOrSuperColumn columnOrSuperColumn = new ColumnOrSuperColumn();
columnOrSuperColumn.setColumn(column);
Mutation mutation = new Mutation();
mutation.setColumn_or_supercolumn(columnOrSuperColumn);
mutations.add(mutation);
// Add a new column
column = new Column("birthday".getBytes(ENCODING), "05-04-1978".getBytes(ENCODING), timestamp);
columnOrSuperColumn = new ColumnOrSuperColumn();
columnOrSuperColumn.setColumn(column);
mutation = new Mutation();
mutation.setColumn_or_supercolumn(columnOrSuperColumn);
mutations.add(mutation);
Map<String, List<Mutation>> mutationsForColumnFamily = new HashMap<String, List<Mutation>>();
mutationsForColumnFamily.put(COLUMN_FAMILY, mutations);
job.put("John Steward", mutationsForColumnFamily);
client.batch_mutate(KEYSPACE, job, ConsistencyLevel.ALL);
} catch (Exception exception) {
exception.printStackTrace();
}
}
/**
* Delete the email address and birthday from John Steward.
*
* @param client the Cassandra client
*/
private static void deleteEmailAndBirthdayFromJohnSteward(Cassandra.Client client) {
try {
long timestamp = System.currentTimeMillis();
// The columns we want to remove
List<byte[]> columns = new ArrayList<byte[]>();
columns.add("email".getBytes(ENCODING));
columns.add("birthday".getBytes(ENCODING));
// Add the columns to a SlicePredicate
SlicePredicate slicePredicate = new SlicePredicate();
slicePredicate.setColumn_names(columns);
Deletion deletion = new Deletion(timestamp);
deletion.setPredicate(slicePredicate);
Mutation mutation = new Mutation();
mutation.setDeletion(deletion);
List<Mutation> mutations = new ArrayList<Mutation>();
mutations.add(mutation);
Map<String, List<Mutation>> mutationsForColumnFamily = new HashMap<String, List<Mutation>>();
mutationsForColumnFamily.put(COLUMN_FAMILY, mutations);
Map<String, Map<String, List<Mutation>>> batch = new HashMap<String, Map<String, List<Mutation>>>();
batch.put("John Steward", mutationsForColumnFamily);
client.batch_mutate(KEYSPACE, batch, ConsistencyLevel.ALL);
} catch (Exception exception) {
exception.printStackTrace();
}
}
/**
* Prints out the information to the console.
*
* @param key the key of the Author
* @param result the result to print out
*/
private static void printToConsole(String key, List<ColumnOrSuperColumn> result) {
try {
System.out.println("Key: '" + key + "'");
for (ColumnOrSuperColumn c : result) {
if (c.getColumn() != null) {
String name = new String(c.getColumn().getName(), ENCODING);
String value = new String(c.getColumn().getValue(), ENCODING);
long timestamp = c.getColumn().getTimestamp();
System.out.println(" name: '" + name + "', value: '" + value + "', timestamp: " + timestamp);
} else {
}
}
} catch (UnsupportedEncodingException exception) {
exception.printStackTrace();
}
}
}
