java动态调用的范例

钟鼓楼

动态调用 JAVA CLASS/JAR，不是难事。只是随便搜索了一下，没有完整的过程。於是，综合了一下，写不个综合的范例，以便提供参考。 目录结构： view plaincopy to clipboardprint? {CURDIR}\DynamicLoad.java 　　　　　 \{test} 　　　　　　　\testLoad.java {CURDIR}\DynamicLoad.java 　　　　　 \{test} 　　　　　　　\testLoad.java testLoad.java 的源码： view plaincopy to clipboardprint? package test; public class testLoad{ public static String testing(String name){ return "Hello, " name "! I am a public static method, I will return a String."; } public static void main(String []argv){ System.out.println("------------------------------Begin."); System.out.println("Hello, dynamac load class testing!"); for(int i=0; i<argv.length; i ) System.out.println("argv[" (i) "]=" argv); System.out.println("------------------------------End."); } } package test; public class testLoad{ public static String testing(String name){ return "Hello, " name "! I am a public static method, I will return a String."; } public static void main(String []argv){ System.out.println("------------------------------Begin."); System.out.println("Hello, dynamac load class testing!"); for(int i=0; i<argv.length; i ) System.out.println("argv[" (i) "]=" argv); System.out.println("------------------------------End."); } }DynamicLoad.java的源码： view plaincopy to clipboardprint? import java.io.File; import java.lang.reflect.Field; import java.lang.reflect.Method; import java.net.URL; import java.net.URLClassLoader; public class DynamicLoad extends URLClassLoader { public static void main(String[] args) throws Exception { dyn_load_class(); dyn_load_jar(); } public static void dyn_load_class() { File xFile = new File("test"); //指向class所在的目录 URL xUrl; try { xUrl = xFile.toURL(); URLClassLoader ClassLoader = new URLClassLoader(new URL[]{xUrl}); Class cd = ClassLoader.loadClass("test.testLoad"); //class名（饱含包名) Field[] f = cd.getDeclaredFields(); for (int k = 0; k < f.length; k ) { System.out.println(f[k]); } Method mainMethod = cd.getMethod("main", new Class[]{String[].class}); String params[]={"aa","bb"}; mainMethod.invoke(null, new Object[] {params});//执行 main 方法 System.out.println("\n"); } catch (Exception e) { e.printStackTrace(); } } public static void dyn_load_jar() { DynamicLoad d = new DynamicLoad(); d.addPath("ttest.jar"); //指向 .jar 具体路径 } public DynamicLoad() { super(new URL[0], ClassLoader.getSystemClassLoader()); } public void addPath(String paths) { if (paths == null || paths.length() <= 0) { return; } String separator = System.getProperty("path.separator"); String[] pathToAdds = paths.split(separator); for (int i = 0; i < pathToAdds.length; i ) { if (pathToAdds != null && pathToAdds.length() > 0) { try { File pathToAdd = new File(pathToAdds).getCanonicalFile(); addURL(pathToAdd.toURL()); System.out.println(pathToAdd.toURL()); Class c = this.loadClass("test.testLoad"); //class名（饱含包名) Field[] f = c.getDeclaredFields(); for (int k = 0; k < f.length; k ) { System.out.println(f[k]); } Method mainMethod = c.getMethod("testing", new Class[]{String.class}); String params="小橙子"; String ret=(String)mainMethod.invoke(null, params);//执行方法 System.out.println("test.testLoad.testing() return:" ret); } catch (Exception e) { e.printStackTrace(); } } } } } import java.io.File; import java.lang.reflect.Field; import java.lang.reflect.Method; import java.net.URL; import java.net.URLClassLoader; [1] [2] public class DynamicLoad extends URLClassLoader { public static void main(String[] args) throws Exception { dyn_load_class(); dyn_load_jar(); } public static void dyn_load_class() { File xFile = new File("test"); //指向class所在的目录 URL xUrl; try { xUrl = xFile.toURL(); URLClassLoader ClassLoader = new URLClassLoader(new URL[]{xUrl}); Class cd = ClassLoader.loadClass("test.testLoad"); //class名（饱含包名) Field[] f = cd.getDeclaredFields(); for (int k = 0; k < f.length; k ) { System.out.println(f[k]); } Method mainMethod = cd.getMethod("main", new Class[]{String[].class}); String params[]={"aa","bb"}; mainMethod.invoke(null, new Object[] {params});//执行 main 方法 System.out.println("\n"); } catch (Exception e) { e.printStackTrace(); } } public static void dyn_load_jar() { DynamicLoad d = new DynamicLoad(); d.addPath("ttest.jar"); //指向 .jar 具体路径 } public DynamicLoad() { super(new URL[0], ClassLoader.getSystemClassLoader()); } public void addPath(String paths) { if (paths == null || paths.length() <= 0) { return; } String separator = System.getProperty("path.separator"); String[] pathToAdds = paths.split(separator); for (int i = 0; i < pathToAdds.length; i ) { if (pathToAdds != null && pathToAdds.length() > 0) { try { File pathToAdd = new File(pathToAdds).getCanonicalFile(); addURL(pathToAdd.toURL()); System.out.println(pathToAdd.toURL()); Class c = this.loadClass("test.testLoad"); //class名（饱含包名) Field[] f = c.getDeclaredFields(); for (int k = 0; k < f.length; k ) { System.out.println(f[k]); } Method mainMethod = c.getMethod("testing", new Class[]{String.class}); String params="小橙子"; String ret=(String)mainMethod.invoke(null, params);//执行方法 System.out.println("test.testLoad.testing() return:" ret); } catch (Exception e) { e.printStackTrace(); } } } } } 再，还有编译方法（保存成一下.cmd文件，双击即可看到结果）： view plaincopy to clipboardprint? @ECHO OFF javac test\*.java jar cvf ttest.jar ./test/*.class javac DynamicLoad.java java DynamicLoad ECHO. 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