在java代码中经常有读取外部资源的要求:如配置文件等等,通常会把配置文件放在classpath下或者在web项目中放在web-inf下.
1.从当前的工作目录中读取:【达内就业】
[java] view plaincopyprint?
try {
1. BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream("wkdir.txt"))); String str;
2.
while ((str = in.readLine()) != null) { System.out.println(str);
3. } in.close();
4. } catch (IOException e) {
5. }
2,从classpath中读取(读取找到的第一个符合名称的文件):【达内培训费用】
[java] view plaincopyprint?
try {
1. InputStream stream = ClassLoader.getSystemResourceAsStream("fileinjar.txt"); BufferedReader in = new BufferedReader(new InputStreamReader(stream));
2. String str;
while ((str = in.readLine()) != null) {
3. System.out.println(str); }
4. in.close(); } catch (IOException e) {
5. }
3,从classpath中读取(读取找到的所有符合名称的文件,如Spring中带有classpath*:前缀的情况就会从classpath中遍历):
[java] view plaincopyprint?
try {
1.
Enumeration resourceUrls = Thread.currentThread().getContextClassLoader().getResources("fileinjar.txt");
2.
while (resourceUrls.hasMoreElements()) {
3. URL url = (URL) resourceUrls.nextElement(); System.out.println(url);
4.
BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
5. String str;
while ((str = in.readLine()) != null) {
6. System.out.println(str); }
7. in.close();
8. }
9. } catch (IOException e) {
10. }
4,从URL中读取:【达内怎么样】
[java] view plaincopyprint?
try {
1.
URL url = new URL("http://blog.csdn.net/kkdelta");
2. System.out.println(url);
3. BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream())); String str;
4.
while ((str = in.readLine()) != null) { System.out.println(str);
5. } in.close();
6.
} catch (IOException e) {
7. e.printStackTrace();
8. }
5,web项目从web-inf文件夹读取(通过得到ServletContext读取,可以在servlet或者能够得到request的类中使用):
[java] view plaincopyprint?
try {
1.
URL url = (URL) getServletContext().getResource("/WEB-INF/webinffile.txt");
2.
// URL url = (URL)req.getSession().getServletContext().getResource("/WEB-INF/webinffile.txt");
System.out.println(url);
3.
BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
4. String str;
while ((str = in.readLine()) != null) {
5. System.out.println(str); }
6. in.close();
7. } catch (IOException e) { e.printStackTrace();
8. }
以上代码在eclipse环境中运行测试过.不过最近在用JUnit的时候,通过ant运行JUnit时通过ClassLoader.getSystemResourceAsStream("file.txt");的方式去找不到文件.改成 Xclass.class.getClassLoader().getResourceAsStream("file.txt");能从ant指定的classpath中找到文件.原因是ClassLoader和Xclass.class.getClassLoader()是不同的,查找的路径不一样.
