摘要：
1.获取当前路径（绝对路径）package01；importjava.io。文件importjava.io。IOException；导入java.net。URL；publicclassHello01｛publicstaticvoidmain（String[]args）｛System.out.println（getCurrentPath1（））；//D:eclipseJavaWork
1. 获取当前路径（绝对路径）
package p01; import java.io.File; import java.io.IOException; import java.net.URL; public class Hello01 { public static void main(String[] args) { System.out.println(getCurrentPath1());// D:eclipseJavaWorkspaceeclipse202006WorkspaceHelloin System.out.println(new Hello01().getCurrentPath2());// D:eclipseJavaWorkspaceeclipse202006WorkspaceHelloinp01 System.out.println(getCurrentPath3());// D:eclipseJavaWorkspaceeclipse202006WorkspaceHello System.out.println(getCurrentPath4());// file:/D:/eclipseJavaWorkspace/eclipse202006Workspace/Hello/bin/ System.out.println(getCurrentPath5());// D:eclipseJavaWorkspaceeclipse202006WorkspaceHelloin System.out.println(getCurrentPath6());// D:eclipseJavaWorkspaceeclipse202006WorkspaceHello System.out.println(getCurrentPath7());// /D:/eclipseJavaWorkspace/eclipse202006Workspace/Hello/bin/ /* 结果： D:eclipseJavaWorkspaceeclipse202006WorkspaceHelloin D:eclipseJavaWorkspaceeclipse202006WorkspaceHelloinp01 D:eclipseJavaWorkspaceeclipse202006WorkspaceHello file:/D:/eclipseJavaWorkspace/eclipse202006Workspace/Hello/bin/ D:eclipseJavaWorkspaceeclipse202006WorkspaceHelloin D:eclipseJavaWorkspaceeclipse202006WorkspaceHello D:eclipseJavaWorkspaceeclipse202006WorkspaceHelloin */ } // 获取当前类的所在工程路径; public static String getCurrentPath1() { File f = new File(Hello01.class.getResource("/").getPath()); return f.getPath(); } // 获取当前类的绝对路径； public String getCurrentPath2() { File f = new File(this.getClass().getResource("").getPath()); return f.getPath(); } // 获取当前类的所在工程路径; public static String getCurrentPath3() { File directory = new File("");// 参数为空 // getCanonicalPath()返回的就是标准的将符号完全解析的路径 String courseFile = ""; try { courseFile = directory.getCanonicalPath(); } catch (IOException e) { e.printStackTrace(); } return courseFile; } // 获取当前类的所在工程路径; // file:/D:/eclipseJavaWorkspace/eclipse202006Workspace/Hello/bin/ public static String getCurrentPath4() { URL path = Thread.currentThread().getContextClassLoader().getResource(""); return path.toString(); } public static String getCurrentPath5() { return System.getProperty("java.class.path"); } public static String getCurrentPath6() { return System.getProperty("user.dir"); } public static String getCurrentPath7() { String path = Thread.currentThread().getContextClassLoader().getResource("").getPath();// /D:/eclipseJavaWorkspace/eclipse202006Workspace/Hello/bin/ String p = new File(path).getAbsolutePath();// D:eclipseJavaWorkspaceeclipse202006WorkspaceHelloin return p; } }
2. 获取资源文件的路径，或读文件
获取src下资源文件编译后的路径（即classes路径）：
String s2 = Thread.currentThread().getContextClassLoader().getResource("").getPath(); // /D:/eclipseJavaWorkspace/eclipse202006Workspace/Hello/bin/
//String s3 = Thread.currentThread().getContextClassLoader().getResource("/").getPath();// java工程下报错：NullPointerException
String s4 = Thread.currentThread().getContextClassLoader().getResource("test.txt").getPath();// /D:/eclipseJavaWorkspace/eclipse202006Workspace/Hello/bin/test.txt
或者 类名.class.getClassLoader().getResource("").getPath();
或者 this.class.getClassLoader().getResource("").getPath();
//此方法获得的path，虽然前面多一个“/”，但仍然可以用于构造File
File file2 = new File(s2);
File file4 = new File(s4);
InputStream in = new BufferedInputStream(new FileInputStream(new File(s2)));
//还可以 使用如下，直接返回输入流对象
InputStream resourceAsStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("test.txt");//test.txt在src夹下（即classpath下）
if(null == resourceAsStream) {
throw new RuntimeException("nullPointer...");
}
else {
StringBuilder sb = new StringBuilder();
byte[] buf = new byte[512];
int len = -1;
try {
while((len = resourceAsStream.read(buf))!=-1) {
sb.append(new String(buf,0,len));
}
System.out.println(sb.toString());
} catch (IOException e) {
e.printStackTrace();
}
}
3. Java中的getResourceAsStream有以下几种：
- 1. Class.getResourceAsStream(String path) ： path 不以’/'开头时默认是从此类所在的包下取资源，以'/'开头则是从ClassPath根下获取。其只是通过path构造一个绝对路径，最终还是由ClassLoader获取资源。
- 2. Class.getClassLoader.getResourceAsStream(String path) ：默认则是从ClassPath根下获取，path不能以’/'开头，最终是由ClassLoader获取资源。
- 3. ServletContext. getResourceAsStream(String path)：默认从WebAPP根目录下取资源，Tomcat下path是否以’/'开头无所谓，当然这和具体的容器实现有关。
- 4. Jsp下的application内置对象就是上面的ServletContext的一种实现。