[android] 保存文件到手机内存详解手机开发

package com.tsh.savefile; 
 
import java.util.Map; 
 
import org.w3c.dom.Text; 
 
import com.tsh.savefile.service.LoginService; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.text.TextUtils; 
import android.view.View; 
import android.widget.CheckBox; 
import android.widget.EditText; 
import android.widget.Toast; 
 
public class MainActivity extends Activity { 
    private EditText et_username; 
    private EditText et_password; 
    private CheckBox cb_rember; 
    protected void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.activity_main); 
        et_username=(EditText) findViewById(R.id.et_username); 
        et_password=(EditText) findViewById(R.id.et_password); 
        cb_rember=(CheckBox) findViewById(R.id.cb_rember); 
        //读取 
        Map<String, String> info=LoginService.getSavedUserInfo(this); 
        if(info != null){ 
            et_username.setText(info.get("username")); 
            et_password.setText(info.get("password")); 
        } 
    } 
    /** 
     * 登陆 
     * @param v 
     */ 
    public void login(View v){ 
        String username=et_username.getText().toString().trim(); 
        String password=et_password.getText().toString().trim(); 
        if(TextUtils.isEmpty(username)||TextUtils.isEmpty(password)){ 
            Toast.makeText(this, "用户名和密码不能为空", Toast.LENGTH_SHORT).show(); 
        } 
        //记住密码 
        if(cb_rember.isChecked()){ 
            Boolean res=LoginService.saveUserInfo(this,username, password); 
            if(res){ 
                Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show(); 
            }else{ 
                Toast.makeText(this, "保存失败", Toast.LENGTH_SHORT).show(); 
            } 
        } 
        //验证 
        if(username.equals("taoshihan")&&password.equals("1")){ 
            Toast.makeText(this, "登陆成功", Toast.LENGTH_SHORT).show(); 
        }else{ 
            Toast.makeText(this, "用户名或密码错误", Toast.LENGTH_SHORT).show(); 
        } 
    } 
}

package com.tsh.savefile.service; 
 
import java.io.BufferedReader; 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.InputStreamReader; 
import java.util.HashMap; 
import java.util.Map; 
 
import android.content.Context; 
 
public class LoginService { 
    /** 
     * 保存用户名和方法的业务方法 
     * @param context 上下文 
     * @param username 用户名 
     * @param password 方法 
     * @return 
     */ 
    public static boolean saveUserInfo(Context context,String username,String password){ 
        File file=new File(context.getFilesDir(),"info1.txt"); 
        try { 
            FileOutputStream fos=new FileOutputStream(file); 
            String info=username+"##"+password; 
            fos.write(info.getBytes()); 
            fos.close(); 
            return true; 
        } catch (Exception e) { 
            e.printStackTrace(); 
            return false; 
        } 
         
    } 
    /** 
     * 读取 
     * @return 
     */ 
    public static Map<String,String> getSavedUserInfo(Context context){ 
        File file=new File(context.getFilesDir(),"info1.txt"); 
        try { 
            FileInputStream fis=new FileInputStream(file); 
            BufferedReader br=new BufferedReader(new InputStreamReader(fis)); 
            String[] res=br.readLine().split("##"); 
            Map<String, String> map=new HashMap<String,String>(); 
            map.put("username", res[0]); 
            map.put("password", res[1]); 
            return map; 
        } catch (Exception e) { 
            e.printStackTrace(); 
            return null; 
        } 
         
    } 
}

<LinearLayout 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:orientation="vertical" 
    tools:context="com.tsh.savefile.MainActivity" > 
 
    <TextView 
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" 
        android:text="登录名" /> 
 
    <EditText 
        android:id="@+id/et_username" 
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" /> 
 
    <TextView 
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" 
        android:text="密码" /> 
 
    <EditText 
        android:id="@+id/et_password" 
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" 
        android:inputType="textPassword" /> 
 
    <RelativeLayout 
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" > 
 
        <CheckBox 
            android:id="@+id/cb_rember" 
            android:layout_width="wrap_content" 
            android:layout_height="wrap_content" 
            android:layout_centerVertical="true" 
            android:checked="true" 
            android:text="记住密码" /> 
 
        <Button 
            android:layout_width="wrap_content" 
            android:layout_height="wrap_content" 
            android:layout_alignParentRight="true" 
            android:onClick="login" 
            android:text="登陆" /> 
    </RelativeLayout> 
 
</LinearLayout>