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Project獲取資源需要一個啟點，加載資源的動作是由ClassLoader來完成的。
Class對象和當前線程對象可以找到當前加載資源的ClassLoader，
通過ClassLoader的getResource(String name)方法及其它衍生出來的方法可以找到Application的啟點及獲取相關資源
private void display() {path=this.getClass().getResource("/loadresource").getPath();System.out.println(path);path=this.getClass().getResource("/loadresource/bp.txt").getPath();System.out.println(path);path=this.getClass().getResource("/").getPath();System.out.println(path);URL url=this.getClass().getResource("loadresource/bp.txt");System.out.println("Is Null:"+(url==null));path=GetResouceTest.class.getClassLoader().getResource("").getPath();System.out.println(path);path=GetResouceTest.class.getClassLoader().getResource("loadresource/bp.txt").getPath();System.out.println(path);url=GetResouceTest.class.getClassLoader().getResource("/loadresource/bp.txt");System.out.println("Is Null:"+(url==null));path=Thread.currentThread().getContextClassLoader().getResource("").getPath();System.out.println(path);path=Thread.currentThread().getContextClassLoader().getResource("loadresource/bp.txt").getPath();System.out.println(path);url=Thread.currentThread().getContextClassLoader().getResource("loadresource/bp.txt");System.out.println("Is Null:"+(url==null));url=Thread.currentThread().getContextClassLoader().getResource("/loadresource/bp.txt");System.out.println("Is Null:"+(url==null));}

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Output:

/E:/java/workspace/test/bin/loadresource /E:/java/workspace/test/bin/loadresource/bp.txt /E:/java/workspace/test/bin/ Is Null:true /E:/java/workspace/test/bin/ /E:/java/workspace/test/bin/loadresource/bp.txt Is Null:true /E:/java/workspace/test/bin/ /E:/java/workspace/test/bin/loadresource/bp.txt Is Null:false Is Null:true

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Conclusion：
java.lang.Class<T>的URL? getResource(String name)時可以使用參數:
(1)"/":代表項目根目錄，也就是ClassPath的root

(2)以"/"開頭的包路徑

java.lang.ClassLoader的URL getResource(String name)時使用參數：
(1)"":代表項目根目錄，也就是ClassPath的root
(2)不以"/"開頭的包路徑

源碼解析：

java.lang.Class

/*** Finds a resource with a given name. The rules for searching resources* associated with a given class are implemented by the defining* {@linkplain ClassLoader class loader} of the class. This method* delegates to this object's class loader. If this object was loaded by* the bootstrap class loader, the method delegates to {@link* ClassLoader#getSystemResource}.** <p> Before delegation, an absolute resource name is constructed from the* given resource name using this algorithm:** <ul>** <li> If the {@code name} begins with a {@code '/'}* (<tt>'&#92;u002f'</tt>), then the absolute name of the resource is the* portion of the {@code name} following the {@code '/'}.** <li> Otherwise, the absolute name is of the following form:** <blockquote>* {@code modified_package_name/name}* </blockquote>** <p> Where the {@code modified_package_name} is the package name of this* object with {@code '/'} substituted for {@code '.'}* (<tt>'&#92;u002e'</tt>).** </ul>** @param name name of the desired resource* @return A {@link java.net.URL} object or {@code null} if no* resource with this name is found* @since JDK1.1*/public java.net.URL getResource(String name) {name = resolveName(name);ClassLoader cl = getClassLoader0();if (cl==null) {// A system class.return ClassLoader.getSystemResource(name);}return cl.getResource(name);} /*** Add a package name prefix if the name is not absolute Remove leading "/"* if name is absolute*/private String resolveName(String name) {if (name == null) {return name;}if (!name.startsWith("/")) {Class<?> c = this;while (c.isArray()) {c = c.getComponentType();}String baseName = c.getName();int index = baseName.lastIndexOf('.');if (index != -1) {name = baseName.substring(0, index).replace('.', '/')+"/"+name;}} else {name = name.substring(1); }return name;}

從源碼看：
（1）java.lang.Class的getResource(String name)方法調用了ClassLoader的getResource(String name)方法；

（2）java.lang.Class的resolveName(String name)方法去掉了name中的第一個字符“/”,

java.lang.Classloader的getResource(String name)的參數name首字母沒有“/”

Extension?section：

如果路徑中有空格及中文在某些場景會出來問題。

可以嘗試在getResource(Sting name).toURL()來解決。

http://www.cnblogs.com/softidea/p/3888829.html

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超強干貨來襲 云風專訪：近40年碼齡，通宵達旦的技術人生

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