doc: PropertySource

Author: huifer

docs/Spring/clazz/PropertySource/Spring-CommandLinePropertySource.md

@@ -0,0 +1,127 @@
+# Spring CommandLinePropertySource
+
+- Author: [HuiFer](https://github.com/huifer)
+- 源码阅读仓库: [SourceHot-spring](https://github.com/SourceHot/spring-framework-read)
+
+
+- 类全路径: `org.springframework.core.env.CommandLinePropertySource`
+- 作用: 用来存储命令行参数
+
+
+
+
+
+```java
+public abstract class CommandLinePropertySource<T> extends EnumerablePropertySource<T> {
+
+   public static final String COMMAND_LINE_PROPERTY_SOURCE_NAME = "commandLineArgs";
+
+   public static final String DEFAULT_NON_OPTION_ARGS_PROPERTY_NAME = "nonOptionArgs";
+
+
+   private String nonOptionArgsPropertyName = DEFAULT_NON_OPTION_ARGS_PROPERTY_NAME;
+
+
+
+   public CommandLinePropertySource(T source) {
+      // 命令行参数, 属性值
+      super(COMMAND_LINE_PROPERTY_SOURCE_NAME, source);
+   }
+
+   public CommandLinePropertySource(String name, T source) {
+      // 参数名称, 参数值
+      super(name, source);
+   }
+
+
+   public void setNonOptionArgsPropertyName(String nonOptionArgsPropertyName) {
+      this.nonOptionArgsPropertyName = nonOptionArgsPropertyName;
+   }
+
+   @Override
+   public final boolean containsProperty(String name) {
+      // 输入值是否等于nonOptionArgs
+      if (this.nonOptionArgsPropertyName.equals(name)) {
+         // 等于后判断参数列表是否为空
+         return !this.getNonOptionArgs().isEmpty();
+      }
+      // 是否存在 name 属性
+      return this.containsOption(name);
+   }
+
+   @Override
+   @Nullable
+   public final String getProperty(String name) {
+      if (this.nonOptionArgsPropertyName.equals(name)) {
+         // 获取 非可选项参数列表
+         Collection<String> nonOptionArguments = this.getNonOptionArgs();
+         if (nonOptionArguments.isEmpty()) {
+            return null;
+         }
+         else {
+            // 可选参数命令行参数
+            return StringUtils.collectionToCommaDelimitedString(nonOptionArguments);
+         }
+      }
+      Collection<String> optionValues = this.getOptionValues(name);
+      if (optionValues == null) {
+         return null;
+      }
+      else {
+         // 命令行参数
+         return StringUtils.collectionToCommaDelimitedString(optionValues);
+      }
+   }
+
+
+   /**
+    * 是否存在 name 的命令行参数
+    */
+   protected abstract boolean containsOption(String name);
+
+   /**
+    * 获取参数列表集合
+    */
+   @Nullable
+   protected abstract List<String> getOptionValues(String name);
+
+   /**
+    * 获取 non-option 参数列表
+    */
+   protected abstract List<String> getNonOptionArgs();
+
+}
+```
+
+
+
+
+
+## getOptionValues
+
+```java
+/**
+ * Return the collection of values associated with the command line option having the
+ * given name.
+ * <ul>
+ * <li>if the option is present and has no argument (e.g.: "--foo"), return an empty
+ * collection ({@code []})</li>
+ * <li>if the option is present and has a single value (e.g. "--foo=bar"), return a
+ * collection having one element ({@code ["bar"]})</li>
+ * <li>if the option is present and the underlying command line parsing library
+ * supports multiple arguments (e.g. "--foo=bar --foo=baz"), return a collection
+ * having elements for each value ({@code ["bar", "baz"]})</li>
+ * <li>if the option is not present, return {@code null}</li>
+ * </ul>
+ *
+ * 获取参数列表集合
+ */
+@Nullable
+protected abstract List<String> getOptionValues(String name);
+```
+
+
+
+阅读注释可以知道该方法可以获取命令行参数的列表. 
+
+- 如 `--foo`作为开头当输入命令行为 `--foo=bar --foo=baz` 在输入参数名称 `foo` 会得到数据`bar,baz` 

docs/Spring/clazz/PropertySource/Spring-ComparisonPropertySource.md

@@ -0,0 +1,44 @@
+# Spring ComparisonPropertySource
+
+- Author: [HuiFer](https://github.com/huifer)
+- 源码阅读仓库: [SourceHot-spring](https://github.com/SourceHot/spring-framework-read)
+
+
+- 整体代码如下.
+    - 下面几个调用方法会直接抛出异常
+        1. getSource
+        1. containsProperty
+        1. getProperty
+
+```java
+	static class ComparisonPropertySource extends StubPropertySource {
+
+		// 异常信息
+		private static final String USAGE_ERROR =
+				"ComparisonPropertySource instances are for use with collection comparison only";
+
+		public ComparisonPropertySource(String name) {
+			super(name);
+		}
+
+		@Override
+		public Object getSource() {
+			// 抛异常
+			throw new UnsupportedOperationException(USAGE_ERROR);
+		}
+
+		@Override
+		public boolean containsProperty(String name) {
+			// 抛异常
+			throw new UnsupportedOperationException(USAGE_ERROR);
+		}
+
+		@Override
+		@Nullable
+		public String getProperty(String name) {
+			// 抛异常
+			throw new UnsupportedOperationException(USAGE_ERROR);
+		}
+	}
+
+```

docs/Spring/clazz/PropertySource/Spring-CompositePropertySource.md

@@ -0,0 +1,105 @@
+# Spring CompositePropertySource
+- Author: [HuiFer](https://github.com/huifer)
+- 源码阅读仓库: [SourceHot-spring](https://github.com/SourceHot/spring-framework-read)
+
+
+- 全路径: `org.springframework.core.env.CompositePropertySource`
+
+- 整体代码如下
+```java
+public class CompositePropertySource extends EnumerablePropertySource<Object> {
+
+	/**
+	 * set 集合
+	 */
+	private final Set<PropertySource<?>> propertySources = new LinkedHashSet<>();
+
+
+	/**
+	 * Create a new {@code CompositePropertySource}.
+	 * @param name the name of the property source
+	 */
+	public CompositePropertySource(String name) {
+		super(name);
+	}
+
+
+	@Override
+	@Nullable
+	public Object getProperty(String name) {
+		// 循环
+		for (PropertySource<?> propertySource : this.propertySources) {
+			// 获取存储内容
+			Object candidate = propertySource.getProperty(name);
+			if (candidate != null) {
+				return candidate;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public boolean containsProperty(String name) {
+		for (PropertySource<?> propertySource : this.propertySources) {
+			// 是否存在name
+			if (propertySource.containsProperty(name)) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	@Override
+	public String[] getPropertyNames() {
+		Set<String> names = new LinkedHashSet<>();
+		for (PropertySource<?> propertySource : this.propertySources) {
+			// 类型不同抛出异常
+			if (!(propertySource instanceof EnumerablePropertySource)) {
+				throw new IllegalStateException(
+						"Failed to enumerate property names due to non-enumerable property source: " + propertySource);
+			}
+			// 批量添加
+			names.addAll(Arrays.asList(((EnumerablePropertySource<?>) propertySource).getPropertyNames()));
+		}
+		// 转换成 array
+		return StringUtils.toStringArray(names);
+	}
+
+
+	/**
+	 * Add the given {@link PropertySource} to the end of the chain.
+	 * @param propertySource the PropertySource to add
+	 */
+	public void addPropertySource(PropertySource<?> propertySource) {
+		this.propertySources.add(propertySource);
+	}
+
+	/**
+	 * Add the given {@link PropertySource} to the start of the chain.
+	 * @param propertySource the PropertySource to add
+	 * @since 4.1
+	 */
+	public void addFirstPropertySource(PropertySource<?> propertySource) {
+		// 头插
+		List<PropertySource<?>> existing = new ArrayList<>(this.propertySources);
+		this.propertySources.clear();
+		this.propertySources.add(propertySource);
+		this.propertySources.addAll(existing);
+	}
+
+	/**
+	 * Return all property sources that this composite source holds.
+	 * @since 4.1.1
+	 */
+	public Collection<PropertySource<?>> getPropertySources() {
+		return this.propertySources;
+	}
+
+
+	@Override
+	public String toString() {
+		return getClass().getSimpleName() + " {name='" + this.name + "', propertySources=" + this.propertySources + "}";
+	}
+
+}
+```

docs/Spring/clazz/PropertySource/Spring-EnumerablePropertySource.md

@@ -0,0 +1,46 @@
+# Spring EnumerablePropertySource
+
+- Author: [HuiFer](https://github.com/huifer)
+- 源码阅读仓库: [SourceHot-spring](https://github.com/SourceHot/spring-framework-read)
+
+- 全路径: `org.springframework.core.env.EnumerablePropertySource`
+- 在这个类中定义了一个抽象方法`getPropertyNames` 用来获取所有的 property 的名称
+
+```java
+	public abstract String[] getPropertyNames();
+```
+- 整体代码如下
+```java
+public abstract class EnumerablePropertySource<T> extends PropertySource<T> {
+
+	public EnumerablePropertySource(String name, T source) {
+		super(name, source);
+	}
+
+	protected EnumerablePropertySource(String name) {
+		super(name);
+	}
+
+
+	/**
+	 * Return whether this {@code PropertySource} contains a property with the given name.
+	 * <p>This implementation checks for the presence of the given name within the
+	 * {@link #getPropertyNames()} array.
+	 *
+	 * 在属性列表中是否存在 properties 
+	 * @param name the name of the property to find
+	 */
+	@Override
+	public boolean containsProperty(String name) {
+		return ObjectUtils.containsElement(getPropertyNames(), name);
+	}
+
+	/**
+	 * Return the names of all properties contained by the
+	 * 获取所有的 properties 名称
+	 * {@linkplain #getSource() source} object (never {@code null}).
+	 */
+	public abstract String[] getPropertyNames();
+
+}
+```

docs/Spring/clazz/PropertySource/Spring-MapPropertySource.md

@@ -0,0 +1,43 @@
+# Spring MapPropertySource
+
+- Author: [HuiFer](https://github.com/huifer)
+- 源码阅读仓库: [SourceHot-spring](https://github.com/SourceHot/spring-framework-read)
+
+
+- 类全路径: `org.springframework.core.env.MapPropertySource`
+- 内部数据结构是一个`Map<String,Object>`
+    这是一个对map的操作.
+      
+- 整体代码如下.
+
+```java
+
+public class MapPropertySource extends EnumerablePropertySource<Map<String, Object>> {
+
+	public MapPropertySource(String name, Map<String, Object> source) {
+		super(name, source);
+	}
+
+
+	@Override
+	@Nullable
+	public Object getProperty(String name) {
+		// 从map中获取 name 对应的value
+		return this.source.get(name);
+	}
+
+	@Override
+	public boolean containsProperty(String name) {
+		// 判断是否存在 name 属性
+		return this.source.containsKey(name);
+	}
+
+	@Override
+	public String[] getPropertyNames() {
+		// 互殴去 map 的所有key
+		return StringUtils.toStringArray(this.source.keySet());
+	}
+
+}
+
+```