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Java方法签名的获取实例代码

2021-04-04 14:37yunshouhu Java教程

这篇文章主要介绍了Java方法签名的获取实例代码,分享了相关代码示例,小编觉得还是挺不错的,具有一定借鉴价值,需要的朋友可以参考下

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:

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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);
    }
}

总结

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原文链接:http://blog.csdn.net/earbao/article/details/77852044

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