Android---6---将数据保存到SD卡

同样是实现上一篇文章中所需要的功能，只不过这次是将数据保存到SD卡中。

MainActivity.java

package com.example.qqlogin;

import java.util.Map;

import com.example.qqlogin.utils.utils;
import com.example.qqlogin.utils.utilsOfSDCard;

import android.app.Activity;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
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;
/**
 * 
 * @author Caesar
 *
 */
public class MainActivity extends Activity implements OnClickListener {

	private EditText numberText;
	private EditText pswText;
	private Button button;
	private CheckBox cb;
	
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		numberText = (EditText) findViewById(R.id.number);
		pswText = (EditText) findViewById(R.id.psw);
		cb = (CheckBox) findViewById(R.id.remember);
		button = (Button) findViewById(R.id.login);
		button.setOnClickListener(this);
		//回显数据
		Map<String, String> userInfoMap = utilsOfSDCard.GetUserInfo(this);
		if (userInfoMap != null){
			numberText.setText(userInfoMap.get("number"));
			pswText.setText(userInfoMap.get("psw"));
		}
	}

	public void onClick(View v) {
		String number = numberText.getText().toString();
		String psw = pswText.getText().toString();

		String Info = "账号" + number + "密码" + psw;
		Toast.makeText(this, Info, 0).show();
		if (TextUtils.isEmpty(number) || TextUtils.isEmpty(psw)) {
			Toast.makeText(this, "请正确填写", 0).show();
		}
		if (cb.isChecked()) {
			if (utilsOfSDCard.SaveUserInfo(this,number, psw))
				Toast.makeText(this, "保存成功", 0).show();
			else {
				Toast.makeText(this,"保存失败", 0).show();
			}
		}
		Toast.makeText(this, "登陆成功", 1).show();
	}
}

utilsOfSDCard.java

package com.example.qqlogin.utils;

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

import android.content.Context;
import android.os.Environment;
import android.text.TextUtils;
/**
 * 保存数据到SD卡
 * 通过Environment.getExternalStorageDirectory();
 * @author Caesar
 *
 */
public class utilsOfSDCard {
	/**
	 * 保存到SD卡
	 * @param context
	 * @param number
	 * @param psw
	 * @return
	 */
	public static boolean SaveUserInfo(Context context, String number,
			String psw) {

		try {
			File SDCardFile = Environment.getExternalStorageDirectory();
			File file = new File(SDCardFile, "data.txt");
			FileOutputStream fos;

			fos = new FileOutputStream(file);

			String data = number + "##" + psw;
			fos.write(data.getBytes());
			fos.flush();
			fos.close();
			return true;
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return false;

	}
	/**
	 * 从SD卡中读取数据
	 * @param context
	 * @return
	 */
	public static Map<String, String> GetUserInfo(Context context) {

		try {
			File sDCardFile = Environment.getExternalStorageDirectory();
			File file = new File(sDCardFile, "data.txt");

			BufferedReader br = new BufferedReader(new InputStreamReader(
					new FileInputStream(file)));
			String readLine = br.readLine();
			if (!TextUtils.isEmpty(readLine)) {
				Map<String, String> userInfoMap = new HashMap<String, String>();
				String split[] = readLine.split("##");
				userInfoMap.put("number", split[0]);
				userInfoMap.put("psw", split[1]);
				return userInfoMap;
			}

		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		return null;

	}
}

Actvity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    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="com.example.qqlogin.MainActivity" >

    
	<EditText 
	    android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/number"
        android:hint="QQ号/手机号/邮箱"
	    />
	
	<EditText 
	    android:layout_width="fill_parent"
        android:layout_height="wrap_content"
	    android:id="@+id/psw"
	    android:inputType="textPassword"
	    android:hint="密码"
	    />
	<CheckBox
	    android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="记住密码"
        android:checked="true"
        android:id="@+id/remember"
	    />
	<Button 
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:id="@+id/login"
	    android:text="登陆"
	    />
</LinearLayout>

还有一点就是需要添加权限，须获得读取SD卡的权限：

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