編輯:關於Android編程
1.SharedPrefereces 只能保存一些簡單的數輕量級.XML 存儲文件名,
數據保存在data/data/basepackage/shared_prefs/myopt.xml中
實例-收藏-記住密碼自動登錄
//一種輕量級的數據存儲方式//通過KEY
存入數據——putxxxx(key,value)
取出數據——getxxxx(key default)
2.讀寫SD卡 SD的根目錄 適用於數據流讀寫
實現步驟:加入讀寫SD卡權限
判斷SD卡是否存在
讀寫文件
3.SQLite 輕量級 .dp文件多用於手機裡
4.Content prowvider內容提供者
網路存儲 在網絡後台存儲
1保存文件內存儲package com.example.jreduch08; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; import android.widget.Toast; import java.io.BufferedReader; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStreamReader; public class InnerIoActivity extends AppCompatActivity { private EditText content; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_inner_io); Button save= (Button) findViewById(R.id.save); Button read= (Button) findViewById(R.id.read); Button delete= (Button) findViewById(R.id.delete); final TextView show= (TextView) findViewById(R.id.show); content= (EditText) findViewById(R.id.content); save.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { saveFile(); } }); read.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { show.setText( readFile()); } }); delete.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { removeFile(); } }); } //保存文件內存儲 public void saveFile(){ FileOutputStream fos=null; /*MODE_APPEND 追加 MODE_PRIVATE 覆蓋 //OpenFileoutput返回一個 輸出字節流 //指向的路徑為data/data/包名/file/ //參數1.文件名稱(如果不存在則自動創建) 參數2.模式MODE_APPEND 文件內容追加 MODE_PRIVATE 文件內容被覆蓋 */ try { fos= openFileOutput("text.txt",MODE_APPEND); String str=content.getText().toString(); try { fos.write(str.getBytes()); Toast.makeText(InnerIoActivity.this,"保存成功",Toast.LENGTH_SHORT).show(); } catch (IOException e) { e.printStackTrace(); } } catch (FileNotFoundException e) { e.printStackTrace(); }finally { if (fos!=null){ try { fos.flush(); fos.close(); } catch (IOException e) { e.printStackTrace(); } } } } //從內存讀文件 public String readFile(){ StringBuilder sbd=new StringBuilder(); BufferedReader reader=null; FileInputStream fis=null; try { fis=openFileInput("text.txt"); reader=new BufferedReader(new InputStreamReader(fis)); try { sbd.append(getFilesDir().getCanonicalPath()); } catch (IOException e) { e.printStackTrace(); } String row=""; try { while ((row=reader.readLine())!=null){ sbd.append(row); } } catch (IOException e) { e.printStackTrace(); } } catch (FileNotFoundException e) { Toast.makeText(getBaseContext(),"文件不存在",Toast.LENGTH_SHORT).show(); e.printStackTrace(); }finally { if (reader!=null){ try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } } return sbd.toString(); } //刪除文件 public void removeFile(){ String[] files=fileList(); for (String str:files){ // Log.d("=====",str); if (str.equals("text.txt")){ deleteFile("text.txt");} } } }
2保存文件到SD卡
從SD卡讀取文件
package com.example.jreduch08; import android.os.Bundle; import android.os.Environment; import android.support.v7.app.AppCompatActivity; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; import android.widget.Toast; 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; public class SaveToSdCarActivity extends AppCompatActivity { private Button save,read,delete; private EditText content; private TextView show; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_inner_io); save= (Button) findViewById(R.id.save); read= (Button) findViewById(R.id.read); delete= (Button) findViewById(R.id.delete); content= (EditText) findViewById(R.id.content); show= (TextView) findViewById(R.id.show); save.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { saveFile(); } }); read.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { show.setText(readFile()); } }); delete.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { removeFile(); } }); } //保存文件到SD卡 public void saveFile(){ FileOutputStream fos=null; //獲取SD卡狀態 String state= Environment.getExternalStorageState(); //判斷SD卡是否就緒 if(!state.equals(Environment.MEDIA_MOUNTED)){ Toast.makeText(this,"請檢查SD卡",Toast.LENGTH_SHORT).show(); return; } //取得SD卡根目錄 File file= Environment.getExternalStorageDirectory(); try { Log.d("=====SD卡根目錄:",file.getCanonicalPath().toString()); // File myFile=new File(file.getCanonicalPath()+"/sd.txt"); // fos=new FileOutputStream(myFile); //輸出流的構造參數1可以是 File對象 也可以是文件路徑 //輸出流的構造參數2:默認為False=>覆蓋內容;ture=》追加內容 //追加 ,ture fos=new FileOutputStream(file.getCanonicalPath()+"/sd.txt",true); String str=content.getText().toString(); fos.write(str.getBytes()); Toast.makeText(this,"保存成功",Toast.LENGTH_SHORT).show(); } catch (IOException e) { e.printStackTrace(); }finally { if (fos!=null){ try { fos.close(); } catch (IOException e) { e.printStackTrace(); } } } } //從SD卡讀取文件 public String readFile(){ BufferedReader reader=null; FileInputStream fis=null; StringBuilder sbd=new StringBuilder(); String statu=Environment.getExternalStorageState(); if (!statu.equals(Environment.MEDIA_MOUNTED)){ Toast.makeText(this,"SD卡未就緒",Toast.LENGTH_SHORT).show(); return ""; } File root=Environment.getExternalStorageDirectory(); try { fis=new FileInputStream(root+"/sd.txt"); reader= new BufferedReader(new InputStreamReader(fis)); String row=""; try { while ((row=reader.readLine())!=null){ sbd.append(row); } } catch (IOException e) { e.printStackTrace(); } } catch (FileNotFoundException e) { Toast.makeText(this,"文件不存在",Toast.LENGTH_SHORT).show(); e.printStackTrace(); }finally { if (reader!=null){ try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } } return sbd.toString(); } //刪除SD卡文件 public void removeFile(){ String statu=Environment.getExternalStorageState(); if (!statu.equals(Environment.MEDIA_MOUNTED)){ Toast.makeText(this,"SD卡未就緒",Toast.LENGTH_SHORT).show(); return; } File root=Environment.getExternalStorageDirectory(); // File sd=new File(root,"sd.txt"); File sd=new File(root+"/sd.txt"); if(sd.exists()){ sd.delete(); Toast.makeText(this,"文件刪除成功",Toast.LENGTH_SHORT).show(); }else{ Toast.makeText(this,"文件不存在",Toast.LENGTH_SHORT).show(); } } }
3讀取assets目錄 讀取raw文件夾
package com.example.jreduch08; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.TextView; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; public class ReadRawAssetsActivity extends AppCompatActivity { private Button raw,assets; private TextView show; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_read_raw_assets); raw=(Button)findViewById(R.id.raw); assets= (Button) findViewById(R.id.assets); show= (TextView) findViewById(R.id.show); raw.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { show.setText(readRaw()); } }); assets.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { show.setText(readAssets()); } }); } //讀取assets目錄 public String readAssets(){ StringBuilder sbd=new StringBuilder(); BufferedReader reader=null; InputStream is=null; try { is=getResources().getAssets().open("cityinfo"); reader=new BufferedReader(new InputStreamReader(is)); String row=""; while ((row=reader.readLine())!=null){ sbd.append(row); sbd.append("\n"); } } catch (IOException e) { e.printStackTrace(); }finally { if (reader!=null){ try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } } return sbd.toString(); } //讀取raw文件夾 public String readRaw(){ StringBuilder sbd=new StringBuilder(); BufferedReader reader=null; InputStream is=null; is=getResources().openRawResource(R.raw.settings); reader=new BufferedReader(new InputStreamReader(is)); String row=""; try { while ((row=reader.readLine())!=null){ sbd.append(row); } } catch (IOException e) { e.printStackTrace(); }finally { if (reader!=null){ try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } } return sbd.toString(); } }
4
將圖片保存到SD卡
從SD卡讀取圖片
從網絡獲取圖片
從網絡獲取圖片直接保存
package com.example.jreduch08; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.drawable.BitmapDrawable; import android.os.AsyncTask; import android.os.Bundle; import android.os.Environment; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.ImageView; import android.widget.Toast; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; public class ViewPagerSdActivity extends AppCompatActivity { private ImageView img1,img2; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_view_pager_sd); img1= (ImageView) findViewById(R.id.img1); img2= (ImageView) findViewById(R.id.img2); } //從網絡獲取圖片直接保存 public void SaveHttp(View view){ new SaveHttpImg().execute("http://p2.so.qhmsg.com/t0165453974dc3b9af7.jpg"); } //從網絡獲取圖片 public void GetUrlImg(View view){ new GetImg().execute("http://p1.so.qhmsg.com/dm/365_365_/t01df531d143d2554d7.jpg"); } //保存網絡圖片 public void SaveUrlImg(View view){ new Get2Img().execute("http://p1.so.qhmsg.com/dm/365_365_/t01df531d143d2554d7.jpg"); } //從SD卡讀取圖片 public void rawImg(View view){ String path=Environment.getExternalStorageDirectory()+"/1.png"; //方法一 根據URI加載數據圖片 // img2.setImageURI(Uri.parse(path)); // 方法二:通過BitmapFactory的靜態方法decodeFile() // 參數圖片路徑 Bitmap bitmap= BitmapFactory.decodeFile(path); img2.setImageBitmap(bitmap); /*方法三:通過BitmapFactory的靜態方法 decodeStream() // 參數為 輸入流InputStream try { BitmapFactory.decodeStream(new FileInputStream(path)); } catch (FileNotFoundException e) { e.printStackTrace(); } */ } //將圖片保存到SD卡 //布局監聽 public void saveImg(View view){ //獲取ImageView中的圖片 BitmapDrawable bitmapDrawable=(BitmapDrawable) img1.getDrawable(); Bitmap bitmap=bitmapDrawable.getBitmap(); String statu= Environment.getExternalStorageState(); if (!statu.equals(Environment.MEDIA_MOUNTED)){ Toast.makeText(this,"SD卡未就緒",Toast.LENGTH_SHORT).show(); return; } /* 通過 Bitmap(位圖)壓縮的方法(compress)保存圖片到SD卡 參數1:圖片格式(PNG,JPEG WEBP) 參數2:圖片質量(0-100) 參數3:輸出流 */ File root=Environment.getExternalStorageDirectory(); FileOutputStream fos=null; try { fos=new FileOutputStream(root+"/1.png"); bitmap.compress(Bitmap.CompressFormat.PNG,100,fos); Toast.makeText(this,"圖片保存成功",Toast.LENGTH_SHORT).show(); } catch (FileNotFoundException e) { e.printStackTrace(); }finally { if (fos!=null){ try { fos.close(); } catch (IOException e) { e.printStackTrace(); } } } } //網絡存儲圖片 public void save2Img(){ //獲取ImageView中的圖片 BitmapDrawable bitmapDrawable=(BitmapDrawable) img2.getDrawable(); Bitmap bitmap=bitmapDrawable.getBitmap(); String statu= Environment.getExternalStorageState(); if (!statu.equals(Environment.MEDIA_MOUNTED)){ Toast.makeText(this,"SD卡未就緒",Toast.LENGTH_SHORT).show(); return; } /* 通過 Bitmap(位圖)壓縮的方法(compress)保存圖片到SD卡 參數1:圖片格式(PNG,JPEG WEBP) 參數2:圖片質量(0-100) 參數3:輸出流 */ File root=Environment.getExternalStorageDirectory(); FileOutputStream fos=null; try { fos=new FileOutputStream(root+"/1.png"); bitmap.compress(Bitmap.CompressFormat.PNG,100,fos); Toast.makeText(this,"圖片保存成功",Toast.LENGTH_SHORT).show(); } catch (FileNotFoundException e) { e.printStackTrace(); }finally { if (fos!=null){ try { fos.close(); } catch (IOException e) { e.printStackTrace(); } } } } public class GetImg extends AsyncTask{ //onPreExecute在主線程中執行命令 //進度條的初始化 @Override protected void onPreExecute() { super.onPreExecute(); } //doInBackground在子線程中執行名命令 @Override protected Bitmap doInBackground(String... strings) { HttpURLConnection con = null; InputStream is = null; Bitmap bitmap = null; try { URL url = new URL(strings[0]); con = (HttpURLConnection) url.openConnection(); con.setConnectTimeout(5 * 1000); con.setReadTimeout(5 * 1000); /* *http相應200:成功 * 404未找到 * 500發生錯誤 */ if (con.getResponseCode() == 200) { is = con.getInputStream(); bitmap = BitmapFactory.decodeStream(is); return bitmap; } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if (is != null) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } if (con != null) { con.disconnect(); //斷開連接 } } } return null; } //onPostExecute在UI線程中執行命令 主線程 @Override protected void onPostExecute(Bitmap bitmap) { super.onPostExecute(bitmap); img2.setImageBitmap(bitmap); } } public class Get2Img extends AsyncTask { //onPreExecute在主線程中執行命令 //進度條的初始化 @Override protected void onPreExecute() { super.onPreExecute(); } //doInBackground在子線程中執行名命令 @Override protected Bitmap doInBackground(String... strings) { HttpURLConnection con = null; InputStream is = null; Bitmap bitmap = null; try { URL url = new URL(strings[0]); con = (HttpURLConnection) url.openConnection(); con.setConnectTimeout(5 * 1000); con.setReadTimeout(5 * 1000); /* *http相應200:成功 * 404未找到 * 500發生錯誤 */ if (con.getResponseCode() == 200) { is = con.getInputStream(); bitmap = BitmapFactory.decodeStream(is); return bitmap; } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if (is != null) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } if (con != null) { con.disconnect(); //斷開連接 } } } return null; } //onPostExecute在UI線程中執行命令 主線程 @Override protected void onPostExecute(Bitmap bitmap) { super.onPostExecute(bitmap); img2.setImageBitmap(bitmap); save2Img(); } } public class SaveHttpImg extends AsyncTask { @Override protected String doInBackground(String... strings) { HttpURLConnection con = null; InputStream is = null; try { URL url = new URL(strings[0]); con = (HttpURLConnection) url.openConnection(); con.setConnectTimeout(5*1000); con.setReadTimeout(5*1000); File root = Environment.getExternalStorageDirectory(); FileOutputStream fos = new FileOutputStream(root+"/http.jpg"); if(con.getResponseCode()==200){ is = con.getInputStream(); int next=0; byte[] bytes = new byte[1024]; while ( (next = is.read(bytes))>0){ fos.write(bytes,0,next); } fos.flush(); fos.close(); return root+"/http.jpg"; } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if(is!=null){ try { is.close(); } catch (IOException e) { e.printStackTrace(); } } if(con!=null){ con.disconnect(); } } return ""; } @Override protected void onPostExecute(String s) { super.onPostExecute(s); if(!s.equals("")){ Toast.makeText(ViewPagerSdActivity.this,"保存路徑:"+s,Toast.LENGTH_SHORT).show(); }else{ Toast.makeText(ViewPagerSdActivity.this,"保存失敗:",Toast.LENGTH_SHORT).show(); } } } }
先看下效果吧public class WuliuView extends View { private int mMaginTop; //物流信息
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