遵循本教程的“带字符串的管道”部分:
http://www.jonathanbeard.io/tutorials/CtoJava
我想修改streamtest代码,以便将数据保存到一个变量并将其传递给另一个类。
我试过那样做(见下文),但当我跑
Java- CP。流线型试验
从教程中我了解到:
在类streamtest中找不到main方法,请定义main方法
as:public static void main(字符串[]参数)
我想这是有道理的,但我现在有点纠结于如何解决这个问题。
主要思想是我希望能够从C代码中获取数据,将其放入变量pass(我猜是通过streamtest代码),然后将该变量传递给我的主笔记本类
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
public class StreamTest
{
private static final int buffer = 4096;
public static String main(String [] args, String pass)
{
InputStream is = null;
BufferedInputStream bis = null;
try
{
bis = new BufferedInputStream(System.in,buffer);
StringBuilder sb = new StringBuilder();
sb.append((char)bis.read());
while(bis.available() > 0)
{
sb.append((char)bis.read());
}
System.out.println("JAVA SIDE: "+sb.toString());
pass=sb.toString();
bis.close();
}
catch(IOException ex){}
finally{}
//return pass;
return pass;
}
}
下面是我要将数据传递到的主类
public class mainLaptop
{
public static void main(String arg) throws Exception
{
//Timing out? change the IP!
String ip="192.168.137.127";
String Pi1Q1="Leonardo";
String Pi1Q2="Raphael";
String Pi2Q3="Donatello";
String Pi2Q4="Michelangelo";
String pass=arg;
//pass= StreamTest.main(pass);
Send.send(ip, Pi1Q1, pass);
Send.send(ip, Pi1Q2, pass);
Send.send(ip, Pi2Q3, pass);
Send.send(ip, Pi2Q4, pass);
/* Recv.recv(ip, Pi1Q1);
Recv.recv(ip, Pi1Q2);
Recv.recv(ip, Pi2Q3);
Recv.recv(ip, Pi2Q4);*/
}
}
下面是未修改的streamtest
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
public class StreamTest
{
private static final int buffer = 4096;
public static void main(String[] args) throws Exception
{
String pass=null;
InputStream is = null;
BufferedInputStream bis = null;
try
{
bis = new BufferedInputStream(System.in,buffer);
StringBuilder sb = new StringBuilder();
//sb.append((char)bis.read());
while(bis.available() > 0){
sb.append((char)bis.read());
}
pass = sb.toString();
System.out.println("JAVA SIDE: "+sb.toString());
bis.close();
}
catch(IOException ex)
{
}
finally
{
}
// mainLaptop.main(pass);
}
这是C码
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <inttypes.h>
#define DEBUG 0
#define BUFFER 4096
//open ap.txt for text input
static const char* exFile = "ap.txt";
static char inputBuffer[BUFFER];
int main(int argc, const char** argv)
{
FILE *fp = fopen(exFile,"r");
/*check and see if the pointer is null in otherwords see if the memory
location refered to by fp is set...no memory location should be zero
if you want to reference it
Here are some good ways to do this other than the way I did it below:
if(!fp) {do error}
if(fp == NULL) {do error}
and then there's the way I did it below
*/
if(fp == 0){
fprintf(stderr,"Null pointer exception, check file name.\n");
exit(-1);
}
//check and see if an error occured during open
const int err = ferror(fp);
if(err != 0){
/*
void perror(const char* err)
returns specific error message to string attached.
*/
const char* errMessage = strcat("Something bad happened while opening
file ",exFile);
perror(errMessage);
}
#if (DEBUG == 1)
else
{
fprintf(stderr,"Success opening file!!\n");
}
#endif
setbuf(fp,inputBuffer); //set a buffer for input
uint64_t *num = (uint64_t*) malloc(sizeof(uint64_t));
uint64_t total = 0;
uint64_t n = 0;
//test for eof
/*
feof(*fp) - returns a boolean true if at end of file and false otherwise
*/
while(!feof(fp)){
//fscanf returns the number of items it converted using %llu, if it's not
equal to 1 we don't want to continue
if(fscanf(fp,"%"PRIu64"",num)!=1)
break; //you could do a lot of stuff here as far as error handling but
basically something bad has happened
total+= *num; //add to total the value at memory location num
n++;
#if (DEBUG == 1)
fprintf(stderr,"line number %"PRIu64"\n",n);
#endif
}
free(num);
const double average = (double) total / (double) n;
//close the inputfile
fclose(fp);
//declare our outputfile, use a pipe in this case to a java process
//we open a java process for this process to pipe to, also it is
//technically a bi-directional pipe so we can use any of the modifiers
//like r/w/r+/etc
static const char* outFile = "java -cp . StreamTest";
FILE *fp_out = popen(outFile,"w");
//setbuf(fp_out,outputBuffer);
fprintf(fp_out,"Total: %"PRIu64", Integers: %"PRIu64", Average:
%.4f\n",total,n,average);
/*
int fflush(*fp) pushes any data in the buffer to be written
the return value returns 0 if successful or !=0 if an error
occurs....remember return values in C often equal exceptions
*/
fflush(fp_out);
/*
int
*/
fclose(fp_out);
return 1;
}
这是制作文件
CC ?=gcc
JCC ?= javac
FLAGS ?= -Wall -O2
JFLAGS ?= -g -verbose
all: c_app StreamTest
c_app: c_app.c
$(CC) $(FLAGS) -o c_app c_app.c
StreamTest: StreamTest.java
$(JCC) $(JFLAGS) StreamTest.java $(LIBS)
clean:
rm -f c_app StreamTest.class
文本文件只是一堆数字
我已经更新了streamtest代码并在eclipse中运行了它,但是我的输出是
JAVA SIDE:
[x] Sent ''Leonardo
[x] Sent ''Raphael
[x] Sent ''Donatello
[x] Sent ''Michelangelo
而不是
JAVA SIDE:
[x] Sent 'Total: 4953, Integers: 1000, Average: 4.9530'Leonardo
[x] Sent 'Total: 4953, Integers: 1000, Average: 4.9530'Raphael
[x] Sent 'Total: 4953, Integers: 1000, Average: 4.9530'Donatello
[x] Sent 'Total: 4953, Integers: 1000, Average: 4.9530'Michelangelo
更新的streamtest
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
public class StreamTest
{
private static final int buffer = 4096;
public static void main(String[] args) throws Exception
{
String pass=null;
InputStream is = null;
BufferedInputStream bis = null;
try
{
bis = new BufferedInputStream(System.in,buffer);
StringBuilder sb = new StringBuilder();
//sb.append((char)bis.read());
while(bis.available() > 0){
sb.append((char)bis.read());
}
pass = sb.toString();
System.out.println("JAVA SIDE: "+pass);
bis.close();
}
catch(IOException ex)
{
}
finally
{
}
//pass = "hi";
mainLaptop.main(pass);
}
}
