編輯：Android編程入門
.xml
<?xml version="1.0" encoding="utf-8"?>
<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: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.hanqi.application3.DataActivity1"
android:orientation="vertical">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/et_1"
android:hint="Key"/>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/et_2"
android:hint="Value"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="保存"
android:layout_weight="1"
android:onClick="bt1_onClick"/>
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="讀取"
android:layout_weight="1"
android:onClick="bt2_onClick"/>
</LinearLayout>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/et_3"
android:hint="要保存的內容"/>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/et_4"
android:hint="從文件中讀取的內容"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="保存"
android:layout_weight="1"
android:onClick="bt3_onClick"/>
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="讀取"
android:layout_weight="1"
android:onClick="bt4_onClick"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="保存文件"
android:layout_weight="1"
android:onClick="bt5_onClick"/>
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="讀取文件"
android:layout_weight="1"
android:onClick="bt6_onClick"/>
</LinearLayout>
<ImageView
android:layout_width="80dp"
android:layout_height="80dp"
android:src="@drawable/da1"
android:id="@+id/iv_4"
android:visibility="gone"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="保存到帶包名的目錄"
android:layout_weight="1"
android:onClick="bt7_onClick"/>
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="從帶包名目錄讀取"
android:layout_weight="1"
android:onClick="bt8_onClick"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="保存到自定義目錄"
android:layout_weight="1"
android:onClick="bt9_onClick"/>
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="從自定義目錄讀取"
android:layout_weight="1"
android:onClick="bt10_onClick"/>
</LinearLayout>
</LinearLayout>
.java 9和10
package com.hanqi.application3;
import android.content.SharedPreferences;
import android.content.res.AssetManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.PrintStream;
public class DataActivity1 extends AppCompatActivity {
EditText et1;
EditText et2;
EditText et3;
EditText et4;
ImageView iv4;
SharedPreferences sp;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_data1);
et1=(EditText)findViewById(R.id.et_1);
et2=(EditText)findViewById(R.id.et_2);
et3=(EditText)findViewById(R.id.et_3);
et4=(EditText)findViewById(R.id.et_4);
iv4= (ImageView)findViewById(R.id.iv_4);
//1.獲取sp的實例，制定了文件名和操作模式 MODE_PRIVATE私有
sp = getSharedPreferences("mydata",MODE_PRIVATE);
}
//操作assets內的文件
public void bt5_onClick(View v)
{
//1.獲取AssetManager
AssetManager am = getAssets();
try{
//2.打開文件,獲取輸入流
InputStream is = am.open("denglu.jpg");
//3.獲取輸出流
FileOutputStream fos2 = openFileOutput("denglu2.jpg",MODE_PRIVATE);
//4.邊度編寫
byte[] bb2 = new byte[1024];
int ii2 = 0;
while ((ii2 = is.read(bb2))>0)
{
fos2.write(bb2,0,ii2);
}
fos2.close();
is.close();
Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();
}
catch (Exception e)
{
e.printStackTrace();
Toast.makeText(DataActivity1.this, "保存失敗", Toast.LENGTH_SHORT).show();
}
}
//從手機內部存儲讀圖片文件
public void bt6_onClick(View v)
{
//改變ImageView的圖片來源，指向手機存儲空間
//1.獲取文件存儲的絕對路徑
String filepath = getFilesDir().getAbsolutePath();
//2.組合完整路徑
filepath += "/denglu2.jpg";
//3.生成位圖實例
Bitmap bm2 = BitmapFactory.decodeFile(filepath);
//4.改變ImageView的圖片來源
iv4.setImageBitmap(bm2);
}
//文件名
final String FILENAME = "test.txt";
public void bt3_onClick(View v)
{
//1.獲取要存儲的內容
String content = et3.getText().toString();
//2.獲取輸出流
try {
FileOutputStream fos1 = openFileOutput(FILENAME, MODE_APPEND);
//3.構造一個打印輸出流
PrintStream pm1 = new PrintStream(fos1);
//4.寫入內容
pm1.println(content);
pm1.close();
fos1.close();
Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(DataActivity1.this, "保存失敗", Toast.LENGTH_SHORT).show();
}
}
public void bt4_onClick(View v)
{
try {
//1.獲取輸入流
FileInputStream fis1 = openFileInput(FILENAME);
//2.定義讀取的數組
byte[] bt11 = new byte[1024];
//3.讀出數據的長度
int ii = 0;
StringBuilder bb1 = new StringBuilder ();
while ((ii = fis1.read(bt11))>0)
{
bb1.append(new String(bt11,0, ii));
}
fis1.close();
//設置顯示讀出的內容
et4.setText(bb1);
Toast.makeText(DataActivity1.this, "顯示成功", Toast.LENGTH_SHORT).show();
}
catch (Exception e)
{
e.printStackTrace();
Toast.makeText(DataActivity1.this, "保存失敗", Toast.LENGTH_SHORT).show();
}
}
//保存
public void bt1_onClick(View v)
{
//1.獲取Key和Value
String key = et1.getText().toString();
String value = et2.getText().toString();
if (key.length() ==0||value.length() == 0)
{
Toast.makeText(DataActivity1.this, "key或value不能為空", Toast.LENGTH_SHORT).show();
}
else {
//2.取得Editor edit編輯器
SharedPreferences.Editor editor = sp.edit();
//3.放入鍵值對
editor.putString(key,value);
//4.提交保存
boolean b = editor.commit();
if (b)
{
Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();
}
else
{
Toast.makeText(DataActivity1.this, "保存失敗", Toast.LENGTH_SHORT).show();
}
}
}
//讀取
public void bt2_onClick(View v)
{
//1.獲取要讀的key
String key = et1.getText().toString();
//2.讀並設置文本框
et2.setText(sp.getString(key,"沒有發現key"));
}
//向外部存儲空間存儲文件 保存到帶包名的目錄
public void bt7_onClick(View v)
{
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
//1.獲取要存儲的內容
String content = et3.getText().toString();
//2.獲取外部帶包名的目錄
//String sdPath = Environment.getExternalStorageDirectory().getAbsolutePath();
//Toast.makeText(DataActivity1.this, "sdPath= "+sdPath, Toast.LENGTH_SHORT).show();
//參數 代表不同文件類型的子目錄，如果沒有，就傳null
String sdPath = getExternalFilesDir(null).getAbsolutePath();
Toast.makeText(DataActivity1.this, "sdPath = "+sdPath, Toast.LENGTH_SHORT).show();
//3.構造輸出流
sdPath += "/" +FILENAME;
try {
FileOutputStream fos3 = new FileOutputStream(sdPath);
//傳統方式 字節數組方式
fos3.write(content.getBytes("utf-8"));
fos3.close();
Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();
}
catch (Exception e)
{
e.printStackTrace();
Toast.makeText(DataActivity1.this, "保存失敗", Toast.LENGTH_SHORT).show();
}
}
else
{
Toast.makeText(DataActivity1.this, "SD卡沒有掛載", Toast.LENGTH_SHORT).show();
}
}
//從外部存儲空間讀取文件 帶包名的目錄
public void bt8_onClick(View v) {
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
//1.獲取要存儲的內容
//String content = et3.getText().toString();
//2.獲取外部帶包名的目錄
//String sdPath = Environment.getExternalStorageDirectory().getAbsolutePath();
//Toast.makeText(DataActivity1.this, "sdPath= "+sdPath, Toast.LENGTH_SHORT).show();
//參數 代表不同文件類型的子目錄，如果沒有，就傳null
String sdPath = getExternalFilesDir(null).getAbsolutePath();
//Toast.makeText(DataActivity1.this, "sdPath = "+sdPath, Toast.LENGTH_SHORT).show();
//3.構造輸入流
sdPath += "/" + FILENAME;
try {
FileInputStream fis3 = new FileInputStream(sdPath);
byte[] b = new byte[1024];
int i = 0;
StringBuilder sb1 = new StringBuilder();
while ((i = fis3.read(b)) > 0) {
sb1.append(new String(b, 0, i));
}
et4.setText(sb1);
Toast.makeText(DataActivity1.this, "讀取成功", Toast.LENGTH_SHORT).show();
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(DataActivity1.this, "讀取失敗", Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(DataActivity1.this, "SD卡沒有掛載", Toast.LENGTH_SHORT).show();
}
}
//向外部存儲空間存儲文件 保存到自定義的目錄
public void bt9_onClick(View v)
{
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
//1.獲取要存儲的內容
String content = et3.getText().toString();
//2.獲取外部存儲的根目錄
String sdPath = Environment.getExternalStorageDirectory().getAbsolutePath();
//在sd卡的根目錄下，創建子目錄
sdPath += "/hanqi";
//實例化File 指向一個目錄
File file = new File(sdPath);
//如果不存在
if(!file.exists())
{
//創建目錄
file.mkdirs();
}
Toast.makeText(DataActivity1.this, "sdPath= "+sdPath, Toast.LENGTH_SHORT).show();
//3.構造輸出流
sdPath += "/" +FILENAME;
try {
FileOutputStream fos3 = new FileOutputStream(sdPath);
//傳統方式 字節數組方式
fos3.write(content.getBytes("utf-8"));
fos3.close();
Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();
}
catch (Exception e)
{
e.printStackTrace();
Toast.makeText(DataActivity1.this, "保存失敗", Toast.LENGTH_SHORT).show();
}
}
else
{
Toast.makeText(DataActivity1.this, "SD卡沒有掛載", Toast.LENGTH_SHORT).show();
}
}
//從外部存儲空間讀取文件 帶包名的目錄
public void bt10_onClick(View v) {
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
//1.獲取要存儲的內容
//String content = et3.getText().toString();
//2.獲取外部帶包名的目錄
String sdPath = Environment.getExternalStorageDirectory().getAbsolutePath();
//Toast.makeText(DataActivity1.this, "sdPath= "+sdPath, Toast.LENGTH_SHORT).show();
//參數 代表不同文件類型的子目錄，如果沒有，就傳null
//String sdPath = getExternalFilesDir(null).getAbsolutePath();
//Toast.makeText(DataActivity1.this, "sdPath = "+sdPath, Toast.LENGTH_SHORT).show();
//3.構造輸入流
sdPath += "/hanqi"+"/" + FILENAME;
try {
FileInputStream fis3 = new FileInputStream(sdPath);
byte[] b = new byte[1024];
int i = 0;
StringBuilder sb1 = new StringBuilder();
while ((i = fis3.read(b)) > 0) {
sb1.append(new String(b, 0, i));
}
et4.setText(sb1);
Toast.makeText(DataActivity1.this, "讀取成功", Toast.LENGTH_SHORT).show();
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(DataActivity1.this, "讀取失敗", Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(DataActivity1.this, "SD卡沒有掛載", Toast.LENGTH_SHORT).show();
}
}
}
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
權限
Android入門：綁定本地服務
一、綁定服務介紹 前面文章中講過一般的通過startService開啟的服務，當訪問者關閉時，服務仍然存在；但是如果存在這樣一種情況：訪問者需要與服務進行通信，
Android 活動(Activity)
Android 活動(Activity)活動代表了一個具有用戶界面的單一屏幕，如 Java 的窗口或者幀。Android 的活動是 ContextThem
Android Activity的4種啟動模式詳解（示例）
轉載請注明出處：http://hovertree.com/先介紹下Android對Activity的管理，Android采用Task來管理多個Activity，當我們啟動
Android WebView中的JavaScript代碼使用
在WebView中使用JavaScript 如果你想要載入的頁面中用了JavaScript，你必須為你的WebView使能JavaScript。 一旦使能之後，你也可
