文件操作 - chenruibing的个人空间

外部sd卡读取数据需要权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
	<!-- hint就是类似于qq输入上的阴影字体 -->
   <EditText 
       android:id="@+id/et_number"
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:hint="请输入QQ号"
       
       />
	<!-- 密文输入    android:inputType="textPassword" -->
   	<EditText 
       android:id="@+id/et_password"
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:inputType="textPassword"
       android:hint="密码"
       
       />
   	<!--  android:checked="true"设定默认选中 -->
   	<CheckBox 
   	     android:id="@+id/cb_remerber_pwd"
   	     android:layout_height="wrap_content"
   	     android:layout_width="wrap_content"
   	     android:checked="true"
   	     android:text="记住密码"
   	    />
   	
   	<Button 
         android:id="@+id/bt_login"
   	     android:layout_height="wrap_content"
   	     android:layout_width="wrap_content"
   	     android:text="登陆"
       />
</LinearLayout>

package com.heima.qq;

import java.io.File;
import java.util.Map;

import com.heima.utils.Utils;
import com.heima.utils.UtilsOfSdcard;
import com.heima.utils.UtilsOfSharedPreferences;

import android.app.Activity;
import android.content.DialogInterface;
import android.os.Bundle;
import android.os.StatFs;
import android.text.TextUtils;
import android.text.format.Formatter;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

public class Qq_loginActivity extends Activity implements OnClickListener{
    private static final String TAG = "Qq_loginActivity";
	private CheckBox cbrememberPWD;
	private EditText etnumber;
	private EditText etpassword;

	/** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
//        //自动动态获取包名
//        this.getFilesDir();
        
       Button button =  (Button) findViewById(R.id.bt_login);
       cbrememberPWD = (CheckBox) findViewById(R.id.cb_remerber_pwd);
       etnumber = (EditText) findViewById(R.id.et_number);
       etpassword = (EditText) findViewById(R.id.et_password);
       
       button.setOnClickListener(this);
       
       //回显数据
       Map<String, String> userInfoMap = UtilsOfSharedPreferences.getUserInfo(this);
       if(userInfoMap != null){
    	   etnumber.setText(userInfoMap.get("name"));
    	   etpassword.setText(userInfoMap.get("password"));
       }
    }

	public void onClick(View v) {
		// TODO Auto-generated method stub
		//执行登陆的操作
		Log.w("qqlog", "login");
		
		//取出号码和密码
		String number = etnumber.getText().toString();
		String password = etpassword.getText().toString();
		
		if(TextUtils.isEmpty(number) || TextUtils.isEmpty(password)){
			//吐丝的使用
			//第一参数是那个窗口前使用     第二参数是输入内容   第三参数是输出时间长短
			Toast toast = Toast.makeText(this, "请正确输入", Toast.LENGTH_SHORT);
			toast.show();
			return;
		}
		//判断是否选中记住密码
		if(cbrememberPWD.isChecked()){
			Log.i(TAG, "记住密码: "+number+" and "+password);
			if(UtilsOfSharedPreferences.saveUserInfo(this,number, password)){
				//保存成功
				Toast.makeText(this, "保存密码成功", 0).show();
			}else{
				Toast.makeText(this, "保存密码失败", 0).show();
			}
		}
		//登陆成功     0代表的是时间短的意思
		Toast.makeText(this, "登陆成功", 0).show();
	}
}

存放的是手机自带有的空间

getFilesDir 根据上下文获取文件路径

package com.heima.utils;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;

import android.content.Context;
import android.text.TextUtils;


//存放的是手机自带有的空间
public class Utils {
	public static boolean saveUserInfo(Context context ,String name,String password){
		
		//路径
//		String path = "/data/data/com.heima.qq/itheima28.txt";
		//getFilesDir 根据上下文获取文件路径
		File filesDir = context.getFilesDir();
		File f = new File(filesDir, "itheima28.txt");
		try {
			FileOutputStream fos = new FileOutputStream(f);
			
			//账号和密码用##连接，使得只有一条记录
			String data = name+"##"+password;
			fos.write(data.getBytes());
			fos.flush();
			fos.close();
			return true;
			
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return false;
	}
	
	public static Map<String, String> getUserInfo(Context context){
		//包名不要写死了
//		String path = "/data/data/com.heima.qq/itheima28.txt";
		File fileDir = context.getFilesDir();
		File f = new File(fileDir, "itheima28.txt");
		try {
			FileInputStream fis = new FileInputStream(f);
			
			//字符流转化为字节流
			BufferedReader reader = new BufferedReader(new InputStreamReader(fis));
			
			String text = reader.readLine();
			reader.close();
			if(!TextUtils.isEmpty(text)){
				String[] split = text.split("##");
				Map<String, String> map = new HashMap<String, String>();
				map.put("name", split[0]);
				map.put("password", split[1]);
				return map;
			}
			
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return null;
	}
}

存放的是sd卡

需考虑sd卡是否满了或者是否有sd卡的存在

Environment自动获取外部文件的路径

package com.heima.utils;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;

import android.content.Context;
import android.os.Environment;
import android.text.TextUtils;


//存放的是sd卡
public class UtilsOfSdcard {
	public static boolean saveUserInfo(Context context ,String name,String password){
		//需考虑sd卡是否满了或者是否有sd卡的存在
		
		//判断当前是否有sd卡
		String state = Environment.getExternalStorageState();
		if(!Environment.MEDIA_MOUNTED.equals(state)){
			return false;
		}
		
		try {
			//Environment自动获取外部文件的路径    也就是sd卡的路径
			File sdCardFile = Environment.getExternalStorageDirectory();
			File file = new File(sdCardFile, "itheima28.txt");
			FileOutputStream fos = new FileOutputStream(file);
			
			String data = name+"##"+password;
			fos.write(data.getBytes());
			fos.flush();
			fos.close();
			return true;
			
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return false;
	}
	
	public static Map<String, String> getUserInfo(Context context){
		
		//判断当前是否有sd卡
		String state = Environment.getExternalStorageState();
		if(!Environment.MEDIA_MOUNTED.equals(state)){
			return null;
		}
		File fileDir = Environment.getExternalStorageDirectory();
		File f = new File(fileDir, "itheima28.txt");
		
		try {
			BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(f)));
			
			String text = br.readLine();
			br.close();
			if(!TextUtils.isEmpty("text")){
				String[] split = text.split("##");
				Map<String, String> map = new HashMap<String, String>();
				map.put("name", split[0]);
				map.put("password", split[1]);
				return map;
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return null;
	}
	
	
	
}

使用SharedPreferences来进行读写，可以设置文件读写权限

默认文件所处位置 data/data/包名/shared_prefs/itheima28 还是在本机上，只有sd卡是外部存储

Editor对象存放数据

package com.heima.utils;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;

import android.content.Context;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Environment;
import android.text.TextUtils;


//使用SharedPreferences来进行读写
public class UtilsOfSharedPreferences {
	public static boolean saveUserInfo(Context context ,String name,String password){
		
		try {
			//  /data/data/包名/shared_prefs/itheima28      不用加后缀名，默认是xml，加了也是xml
			SharedPreferences sp = context.getSharedPreferences("itheima28",
					//设置文件的权限类型
					context.MODE_PRIVATE);
			//获得一个编辑对象
			Editor edit = sp.edit();
			//存数据
			edit.putString("number", name);
			edit.putString("password", password);
			//上面只是存放在内存   想要真正存在文件中就要提交以下
			edit.commit();
			return true;
		} catch (Exception e) {
			// TODO: handle exception
			
		}
		return false;
	}
	
	public static Map<String, String> getUserInfo(Context context){
		
		SharedPreferences sp = context.getSharedPreferences("itheima28",
								context.MODE_PRIVATE);
		
		//取数据不用edit   直接取数据     第二参数是取不出或者没有数据是的默认初始值
		String number = sp.getString("number", null);
		String password = sp.getString("password", null);
		
		if(!TextUtils.isEmpty(number) && !TextUtils.isEmpty(password)){
			Map<String, String> map = new HashMap<String, String>();
			map.put("name", number);
			map.put("password", password);
			return map;
		}
		
		return null;
	}	
}