单例模式JDK、Spring、mybatis源码样例

pom.xml

@@ -14,6 +14,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven.compiler.source>1.7</maven.compiler.source>
         <maven.compiler.target>1.7</maven.compiler.target>
+        <org.springframework.version>5.1.0.RELEASE</org.springframework.version>
     </properties>
 
     <dependencies>
@@ -53,6 +54,44 @@
             <version>3.8.1</version>
         </dependency>
 
+        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
+        <dependency>
+            <groupId>org.mybatis</groupId>
+            <artifactId>mybatis</artifactId>
+            <version>3.4.6</version>
+        </dependency>
+
+        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis-spring -->
+        <dependency>
+            <groupId>org.mybatis</groupId>
+            <artifactId>mybatis-spring</artifactId>
+            <version>1.3.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-webmvc</artifactId>
+            <version>${org.springframework.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-oxm</artifactId>
+            <version>${org.springframework.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-jdbc</artifactId>
+            <version>${org.springframework.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-tx</artifactId>
+            <version>${org.springframework.version}</version>
+        </dependency>
+
     </dependencies>
 
     <build>

src/main/java/top/fjy8018/designpattern/pattern/creational/singleton/ContainerSingleton.java

@@ -2,7 +2,9 @@ package top.fjy8018.designpattern.pattern.creational.singleton;
 
 import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.lang3.StringUtils;
+import org.springframework.beans.factory.config.AbstractFactoryBean;
 
+import java.awt.*;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -10,6 +12,11 @@ import java.util.Map;
  * 基于容器（集合）实现单例
  * 适用于类加载时有多个对象需要实例化场景
  *
+ * JDK源码样例：{@link Desktop#getDesktop()}
+ * 其{@link sun.awt.AppContext} 通过{@link HashMap}实现，使用同步保证单例线程安全
+ * Spring 源码样例：{@link AbstractFactoryBean#getObject()} 在156行判断当前类是否已经实例化
+ * 若没有实例化则在{@link AbstractFactoryBean#getEarlySingletonInstance()}中通过代理方式实例化对象
+ *
  * @author F嘉阳
  * @date 2018-09-24 22:31
  */

src/main/java/top/fjy8018/designpattern/pattern/creational/singleton/HungrySingleton.java

@@ -9,6 +9,8 @@ import java.io.Serializable;
  * 优点：写法简单，类加载时初始化，线程安全
  * 缺点：若类不被使用则会造成内存浪费
  *
+ * JDK源码样例：{@link Runtime} 其实例在类加载时实例化并通过{@link Runtime#getRuntime()} 获取
+ *
  * @author F嘉阳
  * @date 2018-09-24 15:38
  */

src/main/java/top/fjy8018/designpattern/pattern/creational/singleton/ThreadLocalInstance.java

@@ -1,8 +1,12 @@
 package top.fjy8018.designpattern.pattern.creational.singleton;
 
+import org.apache.ibatis.executor.ErrorContext;
+
 /**
  * 基于{@link ThreadLocalInstance} 的（伪）单例模式，只能保证线程内单例唯一（空间换时间思想）
  *
+ * mybatis源码样例：{@link ErrorContext#instance()} 返回通过ThreadLocal实现的单例对象LOCAL
+ *
  * @author F嘉阳
  * @date 2018-09-25 16:24
  */

src/test/java/top/fjy8018/designpattern/pattern/creational/singleton/ContainerSingletonTest.java

@@ -57,7 +57,7 @@ class ContainerSingletonTest {
                 e.printStackTrace();
             }
             Object singleton = ContainerSingleton.getInstance("object");
-            log.info(Thread.currentThread().getName() + " " + singleton);
+            log.info(" " + singleton);
         }
     }
 
@@ -73,7 +73,7 @@ class ContainerSingletonTest {
             }
 
             Object singleton = ContainerSingletonHashtable.getInstance("object");
-            log.info(Thread.currentThread().getName() + " " + singleton);
+            log.info(" " + singleton);
         }
     }
 }

src/test/java/top/fjy8018/designpattern/pattern/creational/singleton/LazyDoubleCheckSingletonTest.java

@@ -34,7 +34,7 @@ class LazyDoubleCheckSingletonTest {
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }
-            log.info(Thread.currentThread().getName() + " " + lazySingleton);
+            log.info(" " + lazySingleton);
         }
     }
 }

src/test/java/top/fjy8018/designpattern/pattern/creational/singleton/LazySingletonSynchronizedTest.java

@@ -34,7 +34,7 @@ class LazySingletonSynchronizedTest {
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }
-            log.info(Thread.currentThread().getName() + " " + lazySingleton);
+            log.info(" " + lazySingleton);
         }
     }
 }

src/test/java/top/fjy8018/designpattern/pattern/creational/singleton/LazySingletonTest.java

@@ -41,7 +41,7 @@ class LazySingletonTest {
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }
-            log.info(Thread.currentThread().getName() + " " + lazySingleton);
+            log.info(" " + lazySingleton);
         }
     }
 }

src/test/java/top/fjy8018/designpattern/pattern/creational/singleton/StaticInnerClassSingletonTest.java

@@ -29,7 +29,7 @@ class StaticInnerClassSingletonTest {
             } catch (Exception e) {
                 e.printStackTrace();
             }
-            log.info(Thread.currentThread().getName() + " " + lazySingleton);
+            log.info(" " + lazySingleton);
         }
     }
 }

src/test/java/top/fjy8018/designpattern/pattern/creational/singleton/ThreadLocalInstanceTest.java

@@ -18,7 +18,7 @@ class ThreadLocalInstanceTest {
         // 在主线程中取
         for (int i = 0; i < 5; i++) {
             ThreadLocalInstance instance = ThreadLocalInstance.getInstance();
-            log.info(Thread.currentThread().getName() + " " + instance);
+            log.info(" " + instance);
         }
 
         Thread thread1 = new Thread(new ThreadLocalInstanceTest.MyRunnable());
@@ -40,7 +40,7 @@ class ThreadLocalInstanceTest {
             } catch (Exception e) {
                 e.printStackTrace();
             }
-            log.info(Thread.currentThread().getName() + " " + instance);
+            log.info(" " + instance);
         }
     }
 }