diff --git a/demo/Structural/DependencyInjection/DatabaseConfiguration.php b/demo/Structural/DependencyInjection/DatabaseConfiguration.php
new file mode 100644
index 0000000..8d924be
--- /dev/null
+++ b/demo/Structural/DependencyInjection/DatabaseConfiguration.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace demo\Structural\DependencyInjection;
+
+/**
+ * 数据库配置
+ */
+class DatabaseConfiguration
+{
+    /**
+     * @var string
+     */
+    private $host;
+    
+    /**
+     * @var int
+     */
+    private $port;
+    
+    /**
+     * @var string
+     */
+    private $username;
+    
+    /**
+     * @var string
+     */
+    private $password;
+    
+    public function __construct(string $host, int $port, string $username, string $password)
+    {
+        $this->host     = $host;
+        $this->port     = $port;
+        $this->username = $username;
+        $this->password = $password;
+    }
+    
+    public function getHost() : string
+    {
+        return $this->host;
+    }
+    
+    public function getPort() : int
+    {
+        return $this->port;
+    }
+    
+    public function getUsername() : string
+    {
+        return $this->username;
+    }
+    
+    public function getPassword() : string
+    {
+        return $this->password;
+    }
+}
\ No newline at end of file
diff --git a/demo/Structural/DependencyInjection/DatabaseConnection.php b/demo/Structural/DependencyInjection/DatabaseConnection.php
new file mode 100644
index 0000000..14bb7bb
--- /dev/null
+++ b/demo/Structural/DependencyInjection/DatabaseConnection.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace demo\Structural\DependencyInjection;
+
+/**
+ * 数据库连接
+ */
+class DatabaseConnection
+{
+    /**
+     * @var DatabaseConfiguration
+     */
+    private $configuration;
+    
+    /**
+     * @param DatabaseConfiguration $config
+     */
+    public function __construct(DatabaseConfiguration $config)
+    {
+        $this->configuration = $config;
+    }
+    
+    public function getDsn() : string
+    {
+        // 这仅仅是演示，而不是一个真正的  DSN
+        // 注意，这里只使用了注入的配置。 所以，
+        // 这里是关键的分离关注点。
+        
+        
+        // 将获取的信息 按照 %s:%s@%s:%d 拼装成字符串
+        
+        // 格式化字符串
+        return sprintf(
+            '%s:%s@%s:%d',
+            $this->configuration->getUsername(),
+            $this->configuration->getPassword(),
+            $this->configuration->getHost(),
+            $this->configuration->getPort()
+        );
+    }
+}
\ No newline at end of file
diff --git a/demo/Structural/DependencyInjection/Run.php b/demo/Structural/DependencyInjection/Run.php
new file mode 100644
index 0000000..82ab5ee
--- /dev/null
+++ b/demo/Structural/DependencyInjection/Run.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace demo\Structural\DependencyInjection;
+
+class Run extends \bin\Design
+{
+    
+    /**
+     * 用松散耦合的方式来更好的实现可测试、可维护和可扩展的代码。
+     *
+     * 依赖注入模式：依赖注入（Dependency Injection）是控制反转（Inversion of Control）的一种实现方式。
+     * 要实现控制反转，通常的解决方案是将创建被调用者实例的工作交由 IoC 容器来完成，然后在调用者中注入被调用者（通过构造器 / 方法注入实现），
+     * 这样我们就实现了调用者与被调用者的解耦，该过程被称为依赖注入。
+     *
+     * DatabaseConfiguration 被注入 DatabaseConnection 并获取所需的 $config 。
+     * 如果没有依赖注入模式， 配置将直接创建 DatabaseConnection 。这对测试和扩展来说很不好。
+     *
+     * @inheritDoc
+     */
+    public function setDesignName() : string
+    {
+        return '依赖注入模式（Dependency Injection）';
+    }
+    
+    /**
+     * @inheritDoc
+     */
+    public function setDesignRefUrl() : string
+    {
+        return 'https://learnku.com/docs/php-design-patterns/2018/DependencyInjection/1501';
+    }
+    
+    /**
+     * @inheritDoc
+     */
+    public function main()
+    {
+        // 设置配置信息
+        $config = new DatabaseConfiguration('localhost', 3306, 'domnikl', '1234');
+        // 格式化配置信息
+        $connection = new DatabaseConnection($config);
+        
+        dump($connection->getDsn());
+    }
+}
\ No newline at end of file
diff --git a/demo/Structural/DependencyInjection/Tests/DependencyInjectionTest.php b/demo/Structural/DependencyInjection/Tests/DependencyInjectionTest.php
new file mode 100644
index 0000000..0b8965f
--- /dev/null
+++ b/demo/Structural/DependencyInjection/Tests/DependencyInjectionTest.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace demo\Structural\DependencyInjection\Tests;
+
+use demo\Structural\DependencyInjection\DatabaseConfiguration;
+use demo\Structural\DependencyInjection\DatabaseConnection;
+
+class DependencyInjectionTest extends \PHPUnit\Framework\TestCase
+{
+    public function testDependencyInjection()
+    {
+        $config     = new DatabaseConfiguration('localhost', 3306, 'domnikl', '1234');
+        $connection = new DatabaseConnection($config);
+        
+        $this->assertEquals('domnikl:1234@localhost:3306', $connection->getDsn());
+    }
+}
\ No newline at end of file