[转载]AndroidNDK开发之“文件操作”

其实和上层没什么关系，主要是通过C来完成文件的基本操作。不好意思大家，时间不够，不多说，贴上关键代码。

关键文件代码：

MainActivity.java

package com.scan.file;

import Android.app.Activity;
import Android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {

private static final String TAG = “File”;
private Button doc = null;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

initControls();
}

/**
* 初始化控件
*/
public void initControls() {
doc = (Button) this.findViewById(R.id.btn_do_c);
doc.setOnClickListener(new MyButtonOnClickListener());
}

/**
* 监听ButtonOnClick
*
* @author lxf
*
*/
class MyButtonOnClickListener implements OnClickListener {

@Override
public void onClick(View v) {
switch (v.getId()) {

case R.id.btn_do_c:
String do_c_result = doCMethod();
displayMessage(do_c_result);
break;
}

}

}

/*
* Toast显示消息
*/
private void displayMessage(String msg) {
Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
}

/**
* 测试方法
*
* @return
*/
public native String sayHello();

/**
* 执行C底层的方法
*
* @return
*/
public native String doCMethod();

/*
* 载人本地库文件
*/
static {
System.loadLibrary(“AndroidJni”);
}
}

file.h

#include <string.h>
#include <stdio.h>
#include “define.h”

unsigned short File_Open(FILE_HANDLE** FileHandle, char* name, unsigned short flag,unsigned short mode);

unsigned short File_Close(FILE_HANDLE* FileHandle);

unsigned short File_GetSize(FILE_HANDLE* FileHandle, unsigned long* FileSize);

unsigned short File_Read(FILE_HANDLE* FileHandle, char* buf, unsigned long count,unsigned long* ReadCount);

unsigned short File_Write(FILE_HANDLE* FileHandle, char* buf, unsigned long count,unsigned long* WriteCount);

unsigned short File_Seek(FILE_HANDLE* FileHandle, long offset, short origin,unsigned long* SeekLen);

unsigned short File_Delete(char* name);

unsigned short File_ISExist(char* path);

unsigned short File_Create_Dir(char* dirName);

unsigned short File_Delete_Dir(char* dirName);

Android.mk
LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := AndroidJni
LOCAL_SRC_FILES := AndroidJni.c File.c SyncmlEngine.c

LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -llog

include $(BUILD_SHARED_LIBRARY)

AndroidJni.c

#include <string.h>
#include <jni.h>
#include <android/log.h>
#include “SyncmlEngine.h”

//测试方法sayHello
jstring Java_com_scan_file_MainActivity_sayHello(JNIEnv* env, jobject thiz) {
//打印信息出来
__android_log_print(ANDROID_LOG_INFO, “JNIMsg”, “SayHello”);
return (*env)->NewStringUTF(env, “Hello from JNI ! sayHello”);
}

//执行C底层方法
jstring Java_com_scan_file_MainActivity_doCMethod(JNIEnv* env, jobject thiz) {
//打印信息出来
__android_log_print(ANDROID_LOG_INFO, “JNIMsg”, “doCMethod”);

SyncmlStart();

return (*env)->NewStringUTF(env, “Do C Method OK!”);
}

file.c

#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <dirent.h>
#include <android/log.h>
#include “File.h”

/**
* File_Open–打开文件
* flag–读\写\读写\追加
* mode–如果没有，是否新建
*/
unsigned short File_Open(FILE_HANDLE** FileHandle, char* name,
unsigned short flag, unsigned short mode) {

if (FileHandle == NULL) {
return 100;
}
if (name == NULL) {
return 100;
}
char type[128] = “”;

if (flag == FO_OREAD) {
if (mode != FO_CREATE) {
strcpy(type, “r”); //只读，不建文件
} else {
strcpy(type, “r+”);
}
} else if (flag == FO_OWRITE) {
if (mode != FO_CREATE) {
strcpy(type, “w”); //只写，不建文件
} else {
strcpy(type, “w+”);
}
} else if (flag == FO_RW) {
if (mode != FO_CREATE) {
strcpy(type, “a”);
} else {
strcpy(type, “a+”);
}
} else if (flag == FO_APPEND) {
if (mode != FO_CREATE) {
strcpy(type, “a”);
} else {
strcpy(type, “a+”);
}
}

*FileHandle = fopen(name, type);
return 0;
}

/**
* File_Close–关闭文件
* 返回值
* 0–关闭成功;否则失败
*/
unsigned short File_Close(FILE_HANDLE* FileHandle) {
if (FileHandle == NULL) {
return 100;
}
return fclose(FileHandle);
}

/**
* File_GetSize–得到文件长度
* FileSize–返回文件长度
*/
unsigned short File_GetSize(FILE_HANDLE* FileHandle, unsigned long* FileSize) {
if (FileHandle == NULL) {
return 100;
}
fseek(FileHandle, 0L, SEEK_END);
*FileSize = ftell(FileHandle);
return 0;
}

/**
* File_Read–读取文件到buf
* count–读取的长度
* ReadCount–返回已读取的长度
*/
unsigned short File_Read(FILE_HANDLE* FileHandle, char* buf,
unsigned long count, unsigned long* ReadCount) {
if (FileHandle == NULL) {
return 100;
}
*ReadCount = fread(buf, 1, count, FileHandle);
__android_log_print(ANDROID_LOG_INFO, “JNIMsg”,
“File_Read           ReadCount=%d”, *ReadCount);
return 0;
}

/**
* File_Write–从buf中写入文件
* count–写入的长度
* WriteCount–返回已写入的长度
*/
unsigned short File_Write(FILE_HANDLE* FileHandle, char* buf,
unsigned long count, unsigned long* WriteCount) {
if (FileHandle == NULL) {
return 100;
}
unsigned short write_result = fwrite(buf, count, 1, FileHandle); // 返回值是成功写入的项目数
if(write_result == 1) {
*WriteCount = write_result * count;
}
return write_result;
}

/**
* File_Seek–给文件偏移量
* offset–偏移量
* origin–偏移方向
* SeekLen–返回已偏移的长度
* 返回值0–成功,其他失败
*/
unsigned short File_Seek(FILE_HANDLE* FileHandle, long offset, short origin,
unsigned long* SeekLen) {
unsigned short seek_result = fseek(FileHandle, offset, origin);
if(seek_result == 0) {
*SeekLen = offset;
}
return seek_result;
}

/**
* File_Delete–删除文件
* 0–删除成功  -1–删除失败
*/
unsigned short File_Delete(char* name) {
if (name == NULL) {
return 100;
}
return remove(name);
}

/**
* File_ISExist–判断文件是否存在
* 0存在  -1不存在
*/
unsigned short File_ISExist(char* path) {
if (path == NULL) {
return 100;
}
return access(path, 0);
}

/**
* File_Create_Dir–创建文件目录
* 返回0–成功
*/
unsigned short File_Create_Dir(char* dirName) {
if (dirName == NULL) {
return 100;
}
return mkdir(dirName, S_IRWXU);
}

/**
* File_Delete_Dir–删除文件目录
*/
unsigned short File_Delete_Dir(char* dirName) {
if (dirName == NULL) {
return 100;
}
DIR* dp = NULL;
DIR* dpin = NULL;
char *pathname = (char*) malloc(256);
memset(pathname, 0, 256);
struct dirent* dirp;
dp = opendir(dirName);
if (dp == NULL) {
__android_log_print(ANDROID_LOG_INFO, “JNIMsg”,
“File_Delete_Dir      your input directory is not exist!”);
return 100;
}
while ((dirp = readdir(dp)) != NULL) {
if (strcmp(dirp->d_name, “..”) == 0 || strcmp(dirp->d_name, “.”) == 0)
continue;
strcpy(pathname, dirName);
strcat(pathname, “/”);
strcat(pathname, dirp->d_name);
dpin = opendir(pathname);
if (dpin != NULL) {
closedir(dpin);
dpin = NULL;
File_Delete_Dir(pathname);
} else {
remove(pathname);
}
}
rmdir(dirName);
closedir(dp);
free(pathname);
pathname = NULL;
dirp = NULL;

return 0;
}

有看不懂的地方可以留言，一起探讨。