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 blocke.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 blocke.printStackTrace();}return null;}}
Actvity_main.xml
<LinearLayout xmlns:android=""xmlns: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" ><EditTextandroid:layout_width="fill_parent"android:layout_height="wrap_content"android:id="@+id/number"android:hint="QQ号/手机号/邮箱"/><EditTextandroid:layout_width="fill_parent"android:layout_height="wrap_content"android:id="@+id/psw"android:inputType="textPassword"android:hint="密码"/><CheckBoxandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="记住密码"android:checked="true"android:id="@+id/remember"/><Buttonandroid: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"/>
，世上没有绝望的处境，只有对处境绝望的人。
