new String(byte bytes[]) 的签名是什么答案

【问题标题】：What the signature of new String(byte bytes[])new String(byte bytes[]) 的签名是什么
【发布时间】：2017-07-18 18:33:32
【问题描述】：

从 JNI 调用 String.java 的构造函数时出错。

错误：

java.lang.NoSuchMethodError: no method with name='' signature='([B)Ljava/nio/ByteBuffer;'在类 Ljava/lang/String;

Java：

String str = new String(new byte[]{1, 2});

JNI：

const char *CLS_STRING = "java/lang/String";
const char *MID_NEW_STRING = "<init>";
const char *SIG_NEW_STRING = "([B)Ljava/lang/String;";  // ????

查找 String.java 类

clsString = env->FindClass(CLS_STRING);
if (clsString == NULL) {
    return JNI_ERR;
}

_clsString = (jclass) env->NewWeakGlobalRef(clsString);
if (_clsString == NULL) {
    return JNI_ERR;
}

调用String.java的new String(byte[] b)方法（这里出错，可能是签名错误？）

_midNewString = env->GetMethodID(_clsString, MID_NEW_STRING, SIG_NEW_STRING);
if (_midNewString == NULL) {
    return JNI_ERR;  // ERROR ini here
}

【问题讨论】：

这是javap -s 所说的任何内容。当有一个工具可以每次都正确时，不要尝试为自己构建这些东西。
我试过这样 C:\Program Files\Java\jdk1.8.0_65\bin>javap -s -classpath bin/classes C:\Users\mb99\AppData\Local\Android\sdk\ sources\android-25\java\lang\String.class 错误：找不到类：C:\Users\mb99\AppData\Local\Android\sdk\sources\android-25\java\lang\String.class
使用工具前请查阅工具文档。不要只是猜测。
我尝试用 javac 编译 String.java 像这样 C:\Program Files\Java\jdk1.8.0_65\bin>javac C:\Users\mb99\AppData\Local\Android\sdk\sources \android-25\java\lang\String.java 但我得到了很多错误。
你不必编译String.java。别再猜了。

标签： java android constructor java-native-interface

【解决方案1】：

按照EJP的指示解决了我的问题，谢谢先生。

const char *SIG_NEW_STRING = "([B)V";

为了获得 String.java 类中函数的签名，我像这样使用 javap：

C:\Program Files\Java\jdk1.8.0_65\bin>javap -s java.lang.String

或

C:\Program Files\Java\jdk1.8.0_65\bin>javap -s -classpath bin/classes C:\Users\{your user account}\AppData\Local\Android\sdk\platforms\android-25\java\lang\String.class

结果：

Compiled from "String.java"
public final class java.lang.String implements java.io.Serializable, java.lang.Comparable<java.lang.String>, java.lang.CharSequence {
  public static final java.util.Comparator<java.lang.String> CASE_INSENSITIVE_ORDER;
    descriptor: Ljava/util/Comparator;
  public java.lang.String();
    descriptor: ()V

  public java.lang.String(java.lang.String);
    descriptor: (Ljava/lang/String;)V

  public java.lang.String(char[]);
    descriptor: ([C)V

  public java.lang.String(char[], int, int);
    descriptor: ([CII)V

  public java.lang.String(int[], int, int);
    descriptor: ([III)V

  public java.lang.String(byte[], int, int, int);
    descriptor: ([BIII)V

  public java.lang.String(byte[], int);
    descriptor: ([BI)V

  public java.lang.String(byte[], int, int, java.lang.String) throws java.io.UnsupportedEncodingException;
    descriptor: ([BIILjava/lang/String;)V

  public java.lang.String(byte[], int, int, java.nio.charset.Charset);
    descriptor: ([BIILjava/nio/charset/Charset;)V

  public java.lang.String(byte[], java.lang.String) throws java.io.UnsupportedEncodingException;
    descriptor: ([BLjava/lang/String;)V

  public java.lang.String(byte[], java.nio.charset.Charset);
    descriptor: ([BLjava/nio/charset/Charset;)V

  public java.lang.String(byte[], int, int);
    descriptor: ([BII)V

  public java.lang.String(byte[]);
    descriptor: ([B)V

  public java.lang.String(java.lang.StringBuffer);
    descriptor: (Ljava/lang/StringBuffer;)V

  public java.lang.String(java.lang.StringBuilder);
    descriptor: (Ljava/lang/StringBuilder;)V

  public int length();
    descriptor: ()I

  public boolean isEmpty();
    descriptor: ()Z

  public native char charAt(int);
    descriptor: (I)C

  public int codePointAt(int);
    descriptor: (I)I

  public int codePointBefore(int);
    descriptor: (I)I

  public int codePointCount(int, int);
    descriptor: (II)I

  public int offsetByCodePoints(int, int);
    descriptor: (II)I

  public void getChars(int, int, char[], int);
    descriptor: (II[CI)V

  public void getBytes(int, int, byte[], int);
    descriptor: (II[BI)V

  public byte[] getBytes(java.lang.String) throws java.io.UnsupportedEncodingException;
    descriptor: (Ljava/lang/String;)[B

  public byte[] getBytes(java.nio.charset.Charset);
    descriptor: (Ljava/nio/charset/Charset;)[B

  public byte[] getBytes();
    descriptor: ()[B

  public boolean equals(java.lang.Object);
    descriptor: (Ljava/lang/Object;)Z

  public boolean contentEquals(java.lang.StringBuffer);
    descriptor: (Ljava/lang/StringBuffer;)Z

  public boolean contentEquals(java.lang.CharSequence);
    descriptor: (Ljava/lang/CharSequence;)Z

  public boolean equalsIgnoreCase(java.lang.String);
    descriptor: (Ljava/lang/String;)Z

  public native int compareTo(java.lang.String);
    descriptor: (Ljava/lang/String;)I

  public int compareToIgnoreCase(java.lang.String);
    descriptor: (Ljava/lang/String;)I

  public boolean regionMatches(int, java.lang.String, int, int);
    descriptor: (ILjava/lang/String;II)Z

  public boolean regionMatches(boolean, int, java.lang.String, int, int);
    descriptor: (ZILjava/lang/String;II)Z

  public boolean startsWith(java.lang.String, int);
    descriptor: (Ljava/lang/String;I)Z

  public boolean startsWith(java.lang.String);
    descriptor: (Ljava/lang/String;)Z

  public boolean endsWith(java.lang.String);
    descriptor: (Ljava/lang/String;)Z

  public int hashCode();
    descriptor: ()I

  public int indexOf(int);
    descriptor: (I)I

  public int indexOf(int, int);
    descriptor: (II)I

  public int lastIndexOf(int);
    descriptor: (I)I

  public int lastIndexOf(int, int);
    descriptor: (II)I

  public int indexOf(java.lang.String);
    descriptor: (Ljava/lang/String;)I

  public int indexOf(java.lang.String, int);
    descriptor: (Ljava/lang/String;I)I

  public int lastIndexOf(java.lang.String);
    descriptor: (Ljava/lang/String;)I

  public int lastIndexOf(java.lang.String, int);
    descriptor: (Ljava/lang/String;I)I

  public java.lang.String substring(int);
    descriptor: (I)Ljava/lang/String;

  public java.lang.String substring(int, int);
    descriptor: (II)Ljava/lang/String;

  public java.lang.CharSequence subSequence(int, int);
    descriptor: (II)Ljava/lang/CharSequence;

  public native java.lang.String concat(java.lang.String);
    descriptor: (Ljava/lang/String;)Ljava/lang/String;

  public java.lang.String replace(char, char);
    descriptor: (CC)Ljava/lang/String;

  public boolean matches(java.lang.String);
    descriptor: (Ljava/lang/String;)Z

  public boolean contains(java.lang.CharSequence);
    descriptor: (Ljava/lang/CharSequence;)Z

  public java.lang.String replaceFirst(java.lang.String, java.lang.String);
    descriptor: (Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;

  public java.lang.String replaceAll(java.lang.String, java.lang.String);
    descriptor: (Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;

  public java.lang.String replace(java.lang.CharSequence, java.lang.CharSequence);
    descriptor: (Ljava/lang/CharSequence;Ljava/lang/CharSequence;)Ljava/lang/String;

  public java.lang.String[] split(java.lang.String, int);
    descriptor: (Ljava/lang/String;I)[Ljava/lang/String;

  public java.lang.String[] split(java.lang.String);
    descriptor: (Ljava/lang/String;)[Ljava/lang/String;

  public java.lang.String toLowerCase(java.util.Locale);
    descriptor: (Ljava/util/Locale;)Ljava/lang/String;

  public java.lang.String toLowerCase();
    descriptor: ()Ljava/lang/String;

  public java.lang.String toUpperCase(java.util.Locale);
    descriptor: (Ljava/util/Locale;)Ljava/lang/String;

  public java.lang.String toUpperCase();
    descriptor: ()Ljava/lang/String;

  public java.lang.String trim();
    descriptor: ()Ljava/lang/String;

  public java.lang.String toString();
    descriptor: ()Ljava/lang/String;

  public native char[] toCharArray();
    descriptor: ()[C

  public static java.lang.String format(java.lang.String, java.lang.Object...);
    descriptor: (Ljava/lang/String;[Ljava/lang/Object;)Ljava/lang/String;

  public static java.lang.String format(java.util.Locale, java.lang.String, java.lang.Object...);
    descriptor: (Ljava/util/Locale;Ljava/lang/String;[Ljava/lang/Object;)Ljava/lang/String;

  public static java.lang.String valueOf(java.lang.Object);
    descriptor: (Ljava/lang/Object;)Ljava/lang/String;

  public static java.lang.String valueOf(char[]);
    descriptor: ([C)Ljava/lang/String;

  public static java.lang.String valueOf(char[], int, int);
    descriptor: ([CII)Ljava/lang/String;

  public static java.lang.String copyValueOf(char[], int, int);
    descriptor: ([CII)Ljava/lang/String;

  public static java.lang.String copyValueOf(char[]);
    descriptor: ([C)Ljava/lang/String;

  public static java.lang.String valueOf(boolean);
    descriptor: (Z)Ljava/lang/String;

  public static java.lang.String valueOf(char);
    descriptor: (C)Ljava/lang/String;

  public static java.lang.String valueOf(int);
    descriptor: (I)Ljava/lang/String;

  public static java.lang.String valueOf(long);
    descriptor: (J)Ljava/lang/String;

  public static java.lang.String valueOf(float);
    descriptor: (F)Ljava/lang/String;

  public static java.lang.String valueOf(double);
    descriptor: (D)Ljava/lang/String;

  public native java.lang.String intern();
    descriptor: ()Ljava/lang/String;

  public int compareTo(java.lang.Object);
    descriptor: (Ljava/lang/Object;)I

  static {};
    descriptor: ()V
}

【讨论】：

这里classpath无关紧要，他的命令就这么简单javap -s java.lang.String。
两个命令都可以，我试过了。但是，您的命令示例更简单，谢谢。我改变我的答案:)