XuLiDown
2020-02-22 14:09
package myproxy; import org.apache.commons.io.FileUtils; import javax.tools.JavaCompiler; import javax.tools.StandardJavaFileManager; import javax.tools.ToolProvider; import java.io.File; import java.lang.reflect.Constructor; import java.lang.reflect.Method; public class Proxy { public static Object newProxyInstance(Class infce) throws Exception { String rt = "\r\n"; String methodStr = ""; for(Method m : infce.getMethods()){ methodStr += " @Override" + rt + " public void " + m.getName() + "() {" + rt + " long starttime = System.currentTimeMillis();" + rt + " System.out.println(\"汽车开始行驶....\");" + rt + " m." + m.getName() + "();" + rt + " long endtime = System.currentTimeMillis();" + rt + " System.out.println(\"汽车结束行驶.... 汽车行驶时间:\" " + rt + " + (endtime - starttime) + \"毫秒!\");" + rt + " }" ; } String str = "package myproxy;" + rt + "public class $Proxy0 implements " + infce.getSimpleName()+ " {" + rt + " public $Proxy0(" + infce.getSimpleName() + " m) {" + rt + " super();" + rt + " this.m = m;" + rt + " }" + rt + " private " + infce.getSimpleName() + " m;" + rt + methodStr + rt + "}" ; //产生代理类的java文件 String filename = System.getProperty("user.dir") +"/src/myproxy/$Proxy0.java"; File file = new File(filename); FileUtils.writeStringToFile(file, str); //编译 //拿到编译器 JavaCompiler complier = ToolProvider.getSystemJavaCompiler(); //文件管理者 StandardJavaFileManager fileMgr = complier.getStandardFileManager(null, null, null); //获取文件 Iterable units = fileMgr.getJavaFileObjects(filename); //编译任务 JavaCompiler.CompilationTask t = complier.getTask(null, fileMgr, null, null, null, units); //进行编译 t.call(); fileMgr.close(); //load 到内存 ClassLoader cl = ClassLoader.getSystemClassLoader(); Class c = cl.loadClass("myproxy.$Proxy0"); Constructor ctr = c.getConstructor(infce); return ctr.newInstance(new Car()); } }
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