Android保存文件到手机

activity_main.xml

<RelativeLayout 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: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=".MainActivity" >    <TextView        android:id="@+id/textView1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_alignParentTop="true"        android:layout_marginLeft="28dp"        android:layout_marginTop="26dp"        android:text="请输入用户名：" />    <EditText        android:id="@+id/et_userName"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/textView1"        android:layout_below="@+id/textView1"        android:layout_marginTop="29dp"        android:ems="10"        android:inputType="textPersonName" />    <TextView        android:id="@+id/textView2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/et_userName"        android:layout_below="@+id/et_userName"        android:layout_marginTop="35dp"        android:text="请输入密码：" />    <EditText        android:id="@+id/et_pwd"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/textView2"        android:layout_below="@+id/textView2"        android:layout_marginTop="56dp"        android:ems="10"        android:inputType="textPassword" />    <CheckBox        android:id="@+id/checkBox1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/et_pwd"        android:layout_alignParentBottom="true"        android:layout_marginBottom="40dp"        android:text="记住密码" />    <Button        android:id="@+id/btn_login"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignRight="@+id/et_pwd"        android:layout_alignTop="@+id/checkBox1"        android:text="登录"        android:onClick="login" /></RelativeLayout>

MainActivity.java

package com.demo.iotest;import java.io.IOException;import java.util.Map;import com.demo.loginService.LoginService;import android.os.Bundle;import android.app.Activity;import android.text.TextUtils;import android.util.Log;import android.view.View;import android.widget.CheckBox;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends Activity {private static final String TAG = "MainActivity";private EditText et_userName;private EditText et_pwd;private CheckBox checkBox;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);et_userName = (EditText) findViewById(R.id.et_userName);et_pwd = (EditText)findViewById(R.id.et_pwd);checkBox = (CheckBox) findViewById(R.id.checkBox1);//检查是否有保存的用户名和密码数组，如果有，回显Map<String, String> map;try {map = LoginService.getSavedUserInfo(this);if(map != null){et_userName.setText(map.get("userName"));et_pwd.setText(map.get("pwd"));}} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}public void login(View view){String userName = et_userName.getText().toString().trim();String pwd = et_pwd.getText().toString().trim();if(TextUtils.isEmpty(userName) || TextUtils.isEmpty(pwd)){Toast.makeText(this, "用户名或者密码不能为空", Toast.LENGTH_SHORT).show();}else{//登陆//判断是否保存密码if(checkBox.isChecked()){//保存用户名密码Log.i(TAG, "保存用户名密码");try {boolean result = LoginService.saveUserInfo(this,userName, pwd);if(result){Toast.makeText(this, "保存用户信息成功", 0).show();}else{Toast.makeText(this, "保存用户信息失败", 0).show();}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}//登陆，发送消息到服务器，服务器验证是否正确if("zhangsan".equals(userName) && "123".equals(pwd)){Toast.makeText(this, "登录成功", 0).show();}else{Toast.makeText(this, "登录失败，用户名或者密码错误", 0).show();}}}}

LoginService.java

package com.demo.loginService;import java.io.BufferedReader;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.util.HashMap;import java.util.Map;import android.content.Context;public class LoginService {/** * 保存用户名密码的业务方法 * @param userName 用户名 * @param context 上下文 * @param pwd 密码 * @return true 保存成功 false 保存失败 * @throws IOException  *  * getFileDir  /data/data/包名/files * getCacheDir  /data/data/包名/cache */public static boolean saveUserInfo(Context context,String userName,String pwd) throws IOException{try {//context.getFilesDir();//帮助返回一个目录/data/data/报名/files//File file = new File("/data/data/com.demo.iotest/info.txt");File file = new File(context.getFilesDir(),"info.txt");FileOutputStream fos = new FileOutputStream(file);fos.write((userName + "##" + pwd).getBytes());fos.close();return true;} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();return false;} }public static Map<String,String> getSavedUserInfo(Context context) throws Exception{File file = new File(context.getFilesDir(),"info.txt");try {FileInputStream fis = new FileInputStream(file);BufferedReader br = new BufferedReader(new InputStreamReader(fis));String str = br.readLine();String[] info = str.split("##");Map<String, String> map = new HashMap<String, String>();map.put("userName", info[0]);map.put("pwd", info[1]);return map;} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();return null;}}}

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