javassist:增强型的java反射工具,获取方法参数名
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java的反射是不能获取方法的参数名的。比如：
public?String?concatString(String?param1,String?param2){?
想获取"param1",和"param2"这个参数名，貌似是不行的。借助第三方包javaassist就可以获得。
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整合原作者代码：
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import javassist.ClassPool;import javassist.CtClass;import javassist.CtMethod;import javassist.Modifier;import javassist.NotFoundException;import javassist.bytecode.CodeAttribute;import javassist.bytecode.LocalVariableAttribute;import javassist.bytecode.MethodInfo;public class Test { public static void main(String[] args) { testReflectParamName(); } /** * 反射获取方法参数名称 */ public static void testReflectParamName() { Class clazz = MyClass.class; try { ClassPool pool = ClassPool.getDefault(); CtClass cc = pool.get(clazz.getName()); CtMethod cm = cc.getDeclaredMethod("concatString"); // 使用javaassist的反射方法获取方法的参数名 MethodInfo methodInfo = cm.getMethodInfo(); CodeAttribute codeAttribute = methodInfo.getCodeAttribute(); LocalVariableAttribute attr = (LocalVariableAttribute) codeAttribute .getAttribute(LocalVariableAttribute.tag); if (attr == null) { // exception } String[] paramNames = new String[cm.getParameterTypes().length]; int pos = Modifier.isStatic(cm.getModifiers()) ? 0 : 1; for (int i = 0; i < paramNames.length; i++) paramNames[i] = attr.variableName(i + pos); // paramNames即参数名 for (int i = 0; i < paramNames.length; i++) { System.out.println("参数名" + i + ":" + paramNames[i]); } } catch (NotFoundException e) { e.printStackTrace(); } }}class MyClass { public String concatString(String param1, String param2) { return param1 + param2; }}?
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反射获取参数注解：
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import java.lang.annotation.Annotation;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;import java.lang.reflect.Method;import java.util.Date;import javassist.ClassPool;import javassist.CtClass;import javassist.CtMethod;import javassist.Modifier;import javassist.NotFoundException;import javassist.bytecode.CodeAttribute;import javassist.bytecode.LocalVariableAttribute;import javassist.bytecode.MethodInfo;public class Test { public static void main(String[] args) { testReflectParamName(); // 反射获取方法参数注解 testReflectMethodParamAnno(); } /** * 反射获取方法参数名称 */ public static void testReflectParamName() { Class clazz = MyClass.class; try { ClassPool pool = ClassPool.getDefault(); CtClass cc = pool.get(clazz.getName()); CtMethod cm = cc.getDeclaredMethod("concatString"); // 使用javaassist的反射方法获取方法的参数名 MethodInfo methodInfo = cm.getMethodInfo(); CodeAttribute codeAttribute = methodInfo.getCodeAttribute(); LocalVariableAttribute attr = (LocalVariableAttribute) codeAttribute .getAttribute(LocalVariableAttribute.tag); if (attr == null) { // exception } String[] paramNames = new String[cm.getParameterTypes().length]; int pos = Modifier.isStatic(cm.getModifiers()) ? 0 : 1; for (int i = 0; i < paramNames.length; i++) paramNames[i] = attr.variableName(i + pos); // paramNames即参数名 for (int i = 0; i < paramNames.length; i++) { System.out.println("参数名" + i + ":" + paramNames[i]); } } catch (NotFoundException e) { e.printStackTrace(); } } /** * 反射获取方法参数注解 */ public static void testReflectMethodParamAnno() { Class clazz = MyClass.class; try { // 使用jdk原生的反射方法 Method m = clazz.getDeclaredMethod("datefomat", new Class[] { Date.class }); Annotation[][] annotations = m.getParameterAnnotations(); System.out.println("jdk获取方法参数anno:"+annotations[0][0]); } catch (SecurityException e) { e.printStackTrace(); } catch (NoSuchMethodException e) { e.printStackTrace(); } try { ClassPool pool = ClassPool.getDefault(); CtClass cc = pool.get(clazz.getName()); CtMethod cm = cc.getDeclaredMethod("datefomat"); // 使用javassist的反射方法可以获得参数标注值 Object[][] annotations = cm.getParameterAnnotations(); DateFormat myAnno = (DateFormat) annotations[0][0]; System.out.println("参数注解："+myAnno.value()); } catch (NotFoundException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } }}class MyClass { public String concatString(String param1, String param2) { return param1 + param2; } public String datefomat(@DateFormat("yyyy-MM-dd HH") Date date1) { return date1.toString(); }}// 注解类@Target(ElementType.PARAMETER)@Retention(RetentionPolicy.RUNTIME)@interface DateFormat { String value() default "yyyy-MM-dd";}?
转自：http://www.blogjava.net/Hafeyang/archive/2010/11/13/336114.html
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