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Java方法签名的获取实例代码

2019年07月19日 | 移动技术网IT编程 | 我要评论

本文研究的主要是java方法签名的获取，下面是具体实现实例。

实例代码：

package com.yunshouhu;
import java.lang.reflect.field;
import java.lang.reflect.method;
import java.lang.reflect.type;
import java.util.collection;
import com.alibaba.fastjson.parser.defaultjsonparser;
import com.alibaba.fastjson.parser.jsonlexer;
import com.alibaba.fastjson.parser.deserializer.objectdeserializer;
/** 
 * 获取java的方法签名，参考javah -jni 类路径/javap -s 类路径。 
 * @author wujianhua 
 * @date 2017年9月5日 下午3:25:51 
 * @url http://blog.csdn.net/earbao 
 */
public class asmutilsforjavah {
	public static void main(string[] args) throws exception {
		system.out.println(asmutilsforjavah.getdesc(system.class));
		system.out.println(asmutilsforjavah.getdesc(string.class));
		system.out.println(asmutilsforjavah.getdesc(integer.class));
		system.out.println(asmutilsforjavah.getdesc(int.class));
		method method=asmutilsforjavah.class.getdeclaredmethod("main", string[].class);
		system.out.println("javah -jni");
		system.out.println(asmutilsforjavah.getdesc(method));
		system.out.println(asmutilsforjavah.gettype(system.class));
		system.out.println(asmutilsforjavah.gettype(asmutilsforjavah.class));
	}
	public static boolean isandroid(final string vmname) {
		final string lowervmname = vmname.tolowercase();
		return lowervmname.contains("dalvik") || lowervmname.contains("lemur");
	}
	public static boolean isandroid() {
		return isandroid(system.getproperty("java.vm.name"));
	}
	public static string getdesc(final method method) {
		final stringbuffer buf = new stringbuffer();
		buf.append("(");
		final class<?>[] types = method.getparametertypes();
		for (int i = 0; i < types.length; ++i) {
			buf.append(getdesc(types[i]));
		}
		buf.append(")");
		buf.append(getdesc(method.getreturntype()));
		return buf.tostring();
	}
	public static string getdesc(final class<?> returntype) {
		if (returntype.isprimitive()) {
			return getprimitiveletter(returntype);
		}
		if (returntype.isarray()) {
			return "[" + getdesc(returntype.getcomponenttype());
		}
		return "l" + gettype(returntype) + ";";
	}
	public static string gettype(final class<?> parametertype) {
		if (parametertype.isarray()) {
			return "[" + getdesc(parametertype.getcomponenttype());
		}
		if (!parametertype.isprimitive()) {
			final string clsname = parametertype.getname();
			return clsname.replaceall("\\.", "/");
		}
		return getprimitiveletter(parametertype);
	}
	public static string getprimitiveletter(final class<?> type) {
		if (integer.type.equals(type)) {
			return "i";
		}
		if (void.type.equals(type)) {
			return "v";
		}
		if (boolean.type.equals(type)) {
			return "z";
		}
		if (character.type.equals(type)) {
			return "c";
		}
		if (byte.type.equals(type)) {
			return "b";
		}
		if (short.type.equals(type)) {
			return "s";
		}
		if (float.type.equals(type)) {
			return "f";
		}
		if (long.type.equals(type)) {
			return "j";
		}
		if (double.type.equals(type)) {
			return "d";
		}
		throw new illegalstateexception("type: " + type.getcanonicalname() + " is not a primitive type");
	}
	public static type getmethodtype(final class<?> clazz, final string methodname) {
		try {
			final method method = clazz.getmethod(methodname, (class<?>[]) new class[0]);
			return method.getgenericreturntype();
		}
		catch (exception ex) {
			return null;
		}
	}
	public static type getfieldtype(final class<?> clazz, final string fieldname) {
		try {
			final field field = clazz.getfield(fieldname);
			return field.getgenerictype();
		}
		catch (exception ex) {
			return null;
		}
	}
	public static void parsearray(final collection collection, final objectdeserializer deser, 
	      final defaultjsonparser parser, final type type, final object fieldname) {
		final jsonlexer lexer = parser.getlexer();
		if (lexer.token() == 8) {
			lexer.nexttoken(16);
		}
		parser.accept(14, 14);
		int index = 0;
		while (true) {
			final object item = deser.deserialze(parser, type, (object) index);
			collection.add(item);
			++index;
			if (lexer.token() != 16) {
				break;
			}
			lexer.nexttoken(14);
		}
		parser.accept(15, 16);
	}
}