android-----JNI-----输入输出

网上很多的JNI文章，几乎都是讲的编译成 .SO 几动态库文件，对于编译成可执行文件的很少，然而对编译成可执行文件几乎就是官方文档中的例子，这几天为了项目，自己做了小实验，特记录一下：

首先看一下目录结构：

首先看Android.mk 的内容

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE    := io
LOCAL_SRC_FILES := io.c
include $(BUILD_EXECUTABLE)

首先申明，由于是自己的测试，所以代码写得很丑哦！！！！

io.c 的代码：（为了工程的需要我这里测试的在线程中读写直接在主函数中也可）

  <c程序编译后一定要将libs里面的名为io 的可执行文件拷贝到assets目录里面>

/* * io.c * *  Created on: 2014年1月22日 *      Author: Jason */#include <jni.h>#include <stdio.h>#include <stdlib.h>#include <pthread.h>void *start_routine (void *arg){while (1){char buf[128] = { 0 };printf("please enter input .... \n");fflush(stdout);fgets(buf,128,stdin);printf("copy :  %s\n", buf);fflush(stdout);if(0 == strcmp(buf,"BREAK"))break;memset(buf,0,128);}}int main(){pthread_t thread;if( 0 > pthread_create(&thread, NULL,start_routine, NULL)) {printf("pthread_create failed \n"); }pthread_join(thread,NULL);return 0;}

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android部分

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1、布局

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <TextView        android:id="@+id/textView"        android:background="#bfbfbfbf"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_above="@+id/editText1"        android:layout_alignParentLeft="true"        android:layout_alignParentRight="true"        android:layout_alignParentTop="true"        android:textColor="#003399"        android:textSize="22sp"        android:text="@string/hello_world" />    <Button        android:id="@+id/button1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignBaseline="@+id/button2"        android:layout_alignBottom="@+id/button2"        android:layout_alignLeft="@+id/textView"        android:layout_marginLeft="37dp"        android:text="读" />    <Button        android:id="@+id/button2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_alignRight="@+id/textView"        android:layout_marginBottom="67dp"        android:layout_marginRight="24dp"        android:text="写" />    <EditText        android:id="@+id/editText1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_above="@+id/button1"        android:layout_alignLeft="@+id/textView"        android:layout_alignRight="@+id/textView"        android:layout_marginBottom="96dp"        android:ems="10" /></RelativeLayout>

2、JAVA部分

package com.example.jniio;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import java.io.OutputStreamWriter;import android.os.Bundle;import android.app.Activity;import android.content.pm.PackageInfo;import android.content.pm.PackageManager.NameNotFoundException;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;public class MainActivity extends Activity {private static final String TAG = "CALLJNI";private TextView textView = null;private Button readButton = null;private Button writeButton = null;private EditText editText = null;private Process process = null;private PackageInfo mPInfo = null;private String text = "";@Overrideprotected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);init(); // ----- 实例化组件copyApplication("io"); //加载可执行文件//开线程，不阻碍ui线程new Thread(new Runnable(){@Overridepublic void run(){try{//调用程序Log.i(TAG, "process action ....  ");process = new ProcessBuilder().directory(new File(mPInfo.applicationInfo.dataDir)).redirectErrorStream(true).command("./io").start();Log.i(TAG, "process actioned ");}catch (IOException e1){e1.printStackTrace();Log.e(TAG, "process wrong !!! ");}}}).start();}/** * 初始化 ---- 实例化 */private void init(){this.textView = (TextView) findViewById(R.id.textView);this.readButton = (Button) findViewById(R.id.button1);this.writeButton = (Button) findViewById(R.id.button2);this.editText = (EditText) findViewById(R.id.editText1);try{mPInfo = getPackageManager().getPackageInfo(getPackageName(), 0);}catch (NameNotFoundException e2){Log.e(TAG, "mPInfo  wrong !!! ");e2.printStackTrace();}textView.setText(text);readButton.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v){text += "<<<: "+read()+"\n";Log.i(TAG, "<<< 读 ： "+text);textView.setText(text);}});writeButton.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v){String inputString = editText.getText().toString();Log.i(TAG, "<<< 写 ： "+inputString);write(inputString+"\n");text += ">>>: "+inputString +"\n";textView.setText(text);editText.setText("");}});}/** * 写 *  * @param string */public void write(String string){Log.i(TAG, ">>>:write ....   "+string);if (process != null){try{OutputStream out = process.getOutputStream();BufferedWriter bWriter = new BufferedWriter(new OutputStreamWriter(out));bWriter.write(string);bWriter.flush();Log.i(TAG, ">>>:write  OK!   ");}catch (Exception e){// TODO: handle exception}}}/** * 读 */public String read(){String outpString = null;try{InputStream in = process.getInputStream();BufferedReader bReader = new BufferedReader(new InputStreamReader(in));outpString = bReader.readLine();Log.i(TAG, "<<<:read() ....   "+outpString);}catch (Exception e){// TODO: handle exception}return outpString;}/** * android 不会加载除 .so的文件，所以对于可执行文件就得自己手动加载 我把可执行文件拷贝到 assets目录下，在程序运行时，在加载到运行的空间。 *  * @param applicationName 可执行程序名 */public void copyApplication(String applicationName){try{PackageInfo mPInfo = getPackageManager().getPackageInfo(getPackageName(), 0);try{File of = new File(mPInfo.applicationInfo.dataDir + "/" + applicationName);InputStream in = getAssets().open(applicationName);OutputStream out = new FileOutputStream(of);byte[] buf = new byte[1024];int len;while ((len = in.read(buf)) > 0){out.write(buf, 0, len);}in.close();out.close();Log.v(TAG, "copied " + applicationName);}catch (Exception e){Log.e(TAG, "Error: Could not find " + applicationName, e);throw new Exception("Cannot find " + applicationName + " in assets.");}Log.v(TAG, "setting executable flag");Process process = new ProcessBuilder().directory(new File(mPInfo.applicationInfo.dataDir)).redirectErrorStream(true).command("chmod", "777", "./" + applicationName).start();process.waitFor();int rvalue = process.exitValue();Log.v(TAG, "chmod returned : " + rvalue);if (rvalue != 0){Log.v(TAG, "cannot set executable flag");throw new Exception("Cannot set executable flag.");}}catch (Exception e){Log.e(TAG, "could not set up " + applicationName, e);}}@Overrideprotected void onDestroy(){write("BREAK\n");super.onDestroy();}}