Jedis 源代碼閱讀一 —— Jedis
阿新 • • 發佈：2017-08-21
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這是jedis 源代碼文件夾，我們接下來選擇性閱讀重要的接口以及實現。
└─redis
└─clients
├─jedis
│ │ BinaryClient.java
│ │ BinaryJedis.java
│ │ BinaryJedisCluster.java
│ │ BinaryJedisPubSub.java
│ │ BinaryShardedJedis.java
│ │ BitOP.java
│ │ BitPosParams.java Jedis.java
我們每次使用jedis都會初始化一個jedis對象，對下面代碼肯定不會陌生：
public class Jedis extends BinaryJedis implements JedisCommands, MultiKeyCommands,
AdvancedJedisCommands, ScriptingCommands, BasicCommands, ClusterCommands, SentinelCommands {
protected JedisPoolAbstract dataSource = null;
public Jedis() {
super();
}
public Jedis(final String host) {
super(host);
}
public Jedis(final String host, final int port) {
super(host, port);
}
............Jedis對象調用父類BinaryJedis構造器：
public class BinaryJedis implements BasicCommands, BinaryJedisCommands, MultiKeyBinaryCommands,
AdvancedBinaryJedisCommands, BinaryScriptingCommands, Closeable {
protected Client client = null;
protected Transaction transaction = null;
protected Pipeline pipeline = null;
public BinaryJedis() {
client = new Client();
}
public BinaryJedis(final String host) {
URI uri = URI.create(host);
if (uri.getScheme() != null && uri.getScheme().equals("redis")) {
initializeClientFromURI(uri);
} else {
client = new Client(host);
}
}
public BinaryJedis(final String host, final int port) {
client = new Client(host, port);
}
public BinaryJedis(final String host, final int port, final int timeout) {
client = new Client(host, port);
client.setConnectionTimeout(timeout);
client.setSoTimeout(timeout);
}實際上，new Jedis()的初始化中。最重要的是new Client（）這句代碼。
Client 繼承自 BinaryClient
public class Client extends BinaryClient implements Commands {
public Client() {
super();
}
而BinaryClient又繼承自Collection
public class BinaryClient extends Connection {
............
private String password;
private int db;
private boolean isInWatch;
............
public BinaryClient() {
super();
}
............接著我們來看Collection代碼：
public class Connection implements Closeable {
.....
protected Connection sendCommand(final ProtocolCommand cmd, final String... args) {
final byte[][] bargs = new byte[args.length][];
for (int i = 0; i < args.length; i++) {
// 對cmd判空並返回bytes
bargs[i] = SafeEncoder.encode(args[i]);
}
return sendCommand(cmd, bargs);
}
protected Connection sendCommand(final ProtocolCommand cmd) {
return sendCommand(cmd, EMPTY_ARGS);
}
protected Connection sendCommand(final ProtocolCommand cmd, final byte[]... args) {
try {
// 1.建立Socket連接
connect();
// 2.依照協議完畢IO操作，也就是命令的運行
Protocol.sendCommand(outputStream, cmd, args);
return this;
} catch (JedisConnectionException ex) {
/*
* When client send request which formed by invalid protocol, Redis
* send back error message before close connection. We try to read
* it to provide reason of failure.
*/
try {
String errorMessage = Protocol.readErrorLineIfPossible(inputStream);
if (errorMessage != null && errorMessage.length() > 0) {
ex = new JedisConnectionException(errorMessage, ex.getCause());
}
} catch (Exception e) {
/*
* Catch any IOException or JedisConnectionException occurred
* from InputStream#read and just ignore. This approach is safe
* because reading error message is optional and connection will
* eventually be closed.
*/
}
// Any other exceptions related to connection?
broken = true;
throw ex;
}
}
...
// 建立Sock連接
public void connect() {
if (!isConnected()) {
try {
socket = new Socket();
// ->@wjw_add
socket.setReuseAddress(true);
socket.setKeepAlive(true); // Will monitor the TCP connection is
// valid
socket.setTcpNoDelay(true); // Socket buffer Whetherclosed, to
// ensure timely delivery of data
socket.setSoLinger(true, 0); // Control calls close () method,
// the underlying socket is closed
// immediately
// <[email protected]_add
socket.connect(new InetSocketAddress(host, port), connectionTimeout);
socket.setSoTimeout(soTimeout);
outputStream = new RedisOutputStream(socket.getOutputStream());
inputStream = new RedisInputStream(socket.getInputStream());
} catch (IOException ex) {
broken = true;
throw new JedisConnectionException(ex);
}
}
}
...在這裏完畢了Socket連接。並返回這個Socket.
每次我們使用Jedis去運行命令。都是這個持有Soket的client去運行的。
比方：
/**
* Get the value of the specified key. If the key does not exist null is
* returned. If the value stored at key is not a string an error is returned
* because GET can only handle string values.
* <p>
* Time complexity: O(1)
*
* @param key
* @return Bulk reply
*/
@Override
public String get(final String key) {
checkIsInMultiOrPipeline();// 檢查是否在事物中；檢查是否是喲好難過管道技術
client.sendCommand(Protocol.Command.GET, key);// 使用Socket進行IO操作，運行命令
return client.getBulkReply();
}jedis除了繼承的BinaryJedis完畢主要的IO操作。還實現了 JedisCommands, MultiKeyCommands, AdvancedJedisCommands,ScriptingCommands, BasicCommands, ClusterCommands, SentinelCommands
這幾個可使用的命令的接口。
你能夠參考redis自帶的 unitTest，更深入的理解。
http://download.csdn.net/detail/lemon89/9407039
關於soTimeout 與 connectionTimeOut
我不多說了，這個鏈接解釋非常清楚。
http://stackoverflow.com/questions/7360520/connectiontimeout-versus-sockettimeout
Jedis 源代碼閱讀一 —— Jedis