第二章阅读 jedis 源码之 Jedis 类

从第一章源码环境搭建中，Jedis 工具包连接 redis 客户端有三个，这一章主要讲 jedis 类连接 redis。

1、首先看下 jedis 类的继承关系图，可以看出 jedis 功能上以实现各种 command 和继承 BinaryJedis ，并没有很复杂的体系。

2、从名字可以就可以看出来，BinaryJedis 其实就是二进制，实现的方法都是二进制的。

API 文档：BinaryJedis (Jedis 2.1.0 API)

先看看 BinaryJedis 实现了的接口类有：

BasicCommands	定义了redis基础命令，以 ping、DB相关等命令。
BinaryJedisCommands	定义操作 key 的命令方法
MultiKeyBinaryCommands	定义集合、队列的命令方法
AdvancedBinaryJedisCommands	定义了配置和日志的命令对应方法
BinaryScriptingCommands	定义了执行脚本命令的方法
Closeable	定义关闭方法

从这些就可以看到  BinaryJedis 其实就是实现所有 redis 的命令，以二进制的方式实现，下面先看下构造方法：

    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") || uri.getScheme().equals("rediss"))) {
            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 boolean ssl) {
        client = new Client(host, port, ssl);
    }

    public BinaryJedis(final String host, final int port, final boolean ssl,
                       final SSLSocketFactory sslSocketFactory, final SSLParameters sslParameters,
                       final HostnameVerifier hostnameVerifier) {
        client = new Client(host, port, ssl, sslSocketFactory, sslParameters, hostnameVerifier);
    }

    public BinaryJedis(final String host, final int port, final int timeout) {
        client = new Client(host, port);
        client.setConnectionTimeout(timeout);
        client.setSoTimeout(timeout);
    }

    public BinaryJedis(final String host, final int port, final int timeout, final boolean ssl) {
        client = new Client(host, port, ssl);
        client.setConnectionTimeout(timeout);
        client.setSoTimeout(timeout);
    }

    public BinaryJedis(final String host, final int port, final int timeout, final boolean ssl,
                       final SSLSocketFactory sslSocketFactory, final SSLParameters sslParameters,
                       final HostnameVerifier hostnameVerifier) {
        client = new Client(host, port, ssl, sslSocketFactory, sslParameters, hostnameVerifier);
        client.setConnectionTimeout(timeout);
        client.setSoTimeout(timeout);
    }

    public BinaryJedis(final String host, final int port, final int connectionTimeout,
                       final int soTimeout) {
        client = new Client(host, port);
        client.setConnectionTimeout(connectionTimeout);
        client.setSoTimeout(soTimeout);
    }

    public BinaryJedis(final String host, final int port, final int connectionTimeout,
                       final int soTimeout, final boolean ssl) {
        client = new Client(host, port, ssl);
        client.setConnectionTimeout(connectionTimeout);
        client.setSoTimeout(soTimeout);
    }

    public BinaryJedis(final String host, final int port, final int connectionTimeout,
                       final int soTimeout, final boolean ssl, final SSLSocketFactory sslSocketFactory,
                       final SSLParameters sslParameters, final HostnameVerifier hostnameVerifier) {
        client = new Client(host, port, ssl, sslSocketFactory, sslParameters, hostnameVerifier);
        client.setConnectionTimeout(connectionTimeout);
        client.setSoTimeout(soTimeout);
    }

    public BinaryJedis(final JedisShardInfo shardInfo) {
        client = new Client(shardInfo.getHost(), shardInfo.getPort(), shardInfo.getSsl(),
                shardInfo.getSslSocketFactory(), shardInfo.getSslParameters(),
                shardInfo.getHostnameVerifier());
        client.setConnectionTimeout(shardInfo.getConnectionTimeout());
        client.setSoTimeout(shardInfo.getSoTimeout());
        client.setPassword(shardInfo.getPassword());
        client.setDb(shardInfo.getDb());
    }

    public BinaryJedis(URI uri) {
        initializeClientFromURI(uri);
    }

    public BinaryJedis(URI uri, final SSLSocketFactory sslSocketFactory,
                       final SSLParameters sslParameters, final HostnameVerifier hostnameVerifier) {
        initializeClientFromURI(uri, sslSocketFactory, sslParameters, hostnameVerifier);
    }

    public BinaryJedis(final URI uri, final int timeout) {
        initializeClientFromURI(uri);
        client.setConnectionTimeout(timeout);
        client.setSoTimeout(timeout);
    }

    public BinaryJedis(final URI uri, final int timeout, final SSLSocketFactory sslSocketFactory,
                       final SSLParameters sslParameters, final HostnameVerifier hostnameVerifier) {
        initializeClientFromURI(uri, sslSocketFactory, sslParameters, hostnameVerifier);
        client.setConnectionTimeout(timeout);
        client.setSoTimeout(timeout);
    }

    public BinaryJedis(final URI uri, final int connectionTimeout, final int soTimeout) {
        initializeClientFromURI(uri);
        client.setConnectionTimeout(connectionTimeout);
        client.setSoTimeout(soTimeout);
    }

    public BinaryJedis(final URI uri, final int connectionTimeout, final int soTimeout,
                       final SSLSocketFactory sslSocketFactory,final SSLParameters sslParameters,
                       final HostnameVerifier hostnameVerifier) {
        initializeClientFromURI(uri, sslSocketFactory, sslParameters, hostnameVerifier);
        client.setConnectionTimeout(connectionTimeout);
        client.setSoTimeout(soTimeout);
    }

其实这个构造方法，就是redis的一些信息，并没什么特殊的。这里会看到一个 Client 的类，其实 BinaryJedis 的方法实现都是调用 Client 的方法。

下面看下 BinaryJedis 的 get 方法：

    @Override
    public byte[] get(final byte[] key) {
        checkIsInMultiOrPipeline();
        client.get(key);
        return client.getBinaryBulkReply();
    }

    // 如果client正在执行事务或者管道流操作，其它命令无法执行
    protected void checkIsInMultiOrPipeline() {
        if (client.isInMulti()) {
            throw new JedisDataException(
                    "Cannot use Jedis when in Multi. Please use Transaction or reset jedis state.");
        } else if (pipeline != null && pipeline.hasPipelinedResponse()) {
            throw new JedisDataException(
                    "Cannot use Jedis when in Pipeline. Please use Pipeline or reset jedis state .");
        }
    }

通过这个方法其实就可以知道了，BinaryJedis 本身并不具体实现，都是使用的是 client 实现的方法，最后获取返回的二进制字节直接返回。