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android數據存儲之文件存儲方法

2019-12-12 04:38:33
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文件存儲是 Android 中最基本的一種數據存儲方式,它不對存儲的內容進行任何的格式化處理,所有數據都是原封不動的保存到文件當中的。

概述

文件存取的核心就是輸入流和輸出流。

Android文件的操作模式
文件的相關操作方法

文件讀寫的實現

openFileOutput和openFileInput方法

 /**   * openFIleOutput ,openFileInput   * 這兩種方法同sp一樣只能講文件保存到手機內存固定的路徑中,   * 默認為 /data/data/<packageName>/files   */  private void save2File() {    try {      //向文件寫入內容      FileOutputStream os = openFileOutput("file.txt", Context.MODE_PRIVATE);      String text = "寫數據到文件";      os.write(text.getBytes("utf-8"));      //關閉流      os.close();    } catch (FileNotFoundException e) {      e.printStackTrace();    } catch (UnsupportedEncodingException e) {      e.printStackTrace();    } catch (IOException e) {      e.printStackTrace();    }  }  /**   *   */  private void readFile() {    try {      FileInputStream ins = openFileInput("file.txt");      byte[] buffer = new byte[100];      int byteCount = ins.read(buffer);      String text = new String(buffer,0,byteCount,"utf-8");      Toast.makeText(this,text,Toast.LENGTH_SHORT).show();      ins.close();    } catch (FileNotFoundException e) {      e.printStackTrace();    } catch (IOException e) {      e.printStackTrace();    }  }

文件存儲位置

/data/data/<package-name>/files目錄下

openFileOutput和openFileInput方法可以獲得操作文件的OutputStream以及InputStream對象,而且可以通過流對象處理任何文件的數據,但是這兩個方法同SharedPreferences一樣,只能在手機內存卡的指定目錄建立文件,因此在使用上仍然有一定的局限性。

讀取SD卡上的文件
main_activity.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:tools="http://schemas.android.com/tools"  android:id="@+id/LinearLayout1"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:orientation="vertical"  tools:context="com.jay.example.filedemo2.MainActivity">  <TextView    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="清輸入文件名" />  <EditText    android:id="@+id/edittitle"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:hint="文件名" />  <TextView    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="清輸入文件內容" />  <EditText    android:id="@+id/editdetail"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:hint="文件內容" />  <Button    android:id="@+id/btnsave"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="保存到SD卡" />  <Button    android:id="@+id/btnclean"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="清空" />  <Button    android:id="@+id/btnread"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="讀取sd卡中的文件" /></LinearLayout>

接著我們來寫一個SD操作類: SDFileHelper.Java

public class SDFileHelper {  private Context context;  public SDFileHelper() {  }  public SDFileHelper(Context context) {    super();    this.context = context;  }  //往SD卡寫入文件的方法  public void savaFileToSD(String filename, String filecontent) throws Exception {    //如果手機已插入sd卡,且app具有讀寫sd卡的權限    if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {      filename = Environment.getExternalStorageDirectory().getCanonicalPath() + "/" + filename;      //這里就不要用openFileOutput了,那個是往手機內存中寫數據的      FileOutputStream output = new FileOutputStream(filename);      output.write(filecontent.getBytes());      //將String字符串以字節流的形式寫入到輸出流中      output.close();      //關閉輸出流    } else Toast.makeText(context, "SD卡不存在或者不可讀寫", Toast.LENGTH_SHORT).show();  }  //讀取SD卡中文件的方法  //定義讀取文件的方法:  public String readFromSD(String filename) throws IOException {    StringBuilder sb = new StringBuilder("");    if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {      filename = Environment.getExternalStorageDirectory().getCanonicalPath() + "/" + filename;      //打開文件輸入流      FileInputStream input = new FileInputStream(filename);      byte[] temp = new byte[1024];      int len = 0;      //讀取文件內容:      while ((len = input.read(temp)) > 0) {        sb.append(new String(temp, 0, len));      }      //關閉輸入流      input.close();    }    return sb.toString();  }}

接著MainActivity.java實現相關邏輯:

public class MainActivity extends AppCompatActivity implements View.OnClickListener{  private EditText editname;  private EditText editdetail;  private Button btnsave;  private Button btnclean;  private Button btnread;  private Context mContext;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    mContext = getApplicationContext();    bindViews();  }  private void bindViews() {    editname = (EditText) findViewById(R.id.edittitle);    editdetail = (EditText) findViewById(R.id.editdetail);    btnsave = (Button) findViewById(R.id.btnsave);    btnclean = (Button) findViewById(R.id.btnclean);    btnread = (Button) findViewById(R.id.btnread);    btnsave.setOnClickListener(this);    btnclean.setOnClickListener(this);    btnread.setOnClickListener(this);  }  @Override  public void onClick(View v) {    switch (v.getId()){      case R.id.btnclean:        editdetail.setText("");        editname.setText("");        break;      case R.id.btnsave:        String filename = editname.getText().toString();        String filedetail = editdetail.getText().toString();        SDFileHelper sdHelper = new SDFileHelper(mContext);        try        {          sdHelper.savaFileToSD(filename, filedetail);          Toast.makeText(getApplicationContext(), "數據寫入成功", Toast.LENGTH_SHORT).show();        }        catch(Exception e){          e.printStackTrace();          Toast.makeText(getApplicationContext(), "數據寫入失敗", Toast.LENGTH_SHORT).show();        }        break;      case R.id.btnread:        String detail = "";        SDFileHelper sdHelper2 = new SDFileHelper(mContext);        try        {          String filename2 = editname.getText().toString();          detail = sdHelper2.readFromSD(filename2);        }        catch(IOException e){e.printStackTrace();}        Toast.makeText(getApplicationContext(), detail, Toast.LENGTH_SHORT).show();        break;    }  }}

最后別忘記在AndroidManifest.xml寫上讀寫SD卡的權限哦!

<!-- 在SDCard中創建與刪除文件權限 --><uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/><!-- 往SDCard寫入數據權限 --><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

如何判斷虛擬和物理兩種SDK

在默認情況下,會將一部分存儲空間分給虛擬的SD卡使用(一部分用于安裝Android操作系統)

android.os.Enviroment.isExternalStorageRemovalbe()

返回true:SD卡是物理的,反之SD卡是虛擬的。

用于適配不同型號手機,反射獲取SD卡路徑和狀態

package com.turing.base.activity.dataStore.fileStore;import android.content.Context;import android.os.Environment;import android.os.StatFs;import android.os.storage.StorageManager;import android.text.TextUtils;import android.util.Log;import java.io.File;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.concurrent.ConcurrentLinkedQueue;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;/** * 用于適配不同型號手機,反射獲取SD卡路徑和狀態 * */public class DevMountInfo {  private final String TAG = DevMountInfo.class.getSimpleName();  private static final int ERROR = -1;  // class name  private final static String CLASS_NAME = "android.os.storage.StorageVolume";  //remained spare memory size  private static final int REMAINED_SPARE_IN_MB = 100;  // method name  private final static String METHOD_GET_VOLUME_LIST = "getVolumeList";  private final static String METHOD_GET_VOLUME_STATE = "getVolumeState";  private final static String METHOD_IS_REMOVABLE = "isRemovable";  private final static String METHOD_GET_PATH = "getPath";  private final static String MOUNTED = "mounted";  private static DevMountInfo INSTANCE;  private String mSDCardPath = null;  // internal file path  private ConcurrentLinkedQueue<String> mInternalPathList = new ConcurrentLinkedQueue<String>();  // external file path  private ConcurrentLinkedQueue<String> mExternalPathList = new ConcurrentLinkedQueue<String>();  private ExecutorService mExecutor = null;  private DevMountInfo() {    mExecutor = Executors.newSingleThreadExecutor();  }  public static DevMountInfo getInstance() {    synchronized (DevMountInfo.class) {      if (null == INSTANCE) {        INSTANCE = new DevMountInfo();      }      return INSTANCE;    }  }  @Override  protected void finalize() throws Throwable {    super.finalize();    synchronized (DevMountInfo.class) {      mInternalPathList.clear();      mExternalPathList.clear();      mExecutor.shutdown();      INSTANCE = null;    }  }  public void init(final Context context) {    mExecutor.execute(new Runnable() {      @Override      public void run() {        executeInit(context);      }    });  }  public boolean isSDCardFull() {    return REMAINED_SPARE_IN_MB > (getSDCardAvailSpace() * 1024);  }  public boolean isSDCardAvaiable() {    return !mExternalPathList.isEmpty() || !mInternalPathList.isEmpty();  }  public String getSDCardPath() {    return mSDCardPath;  }  public long getSDCardTotalSpace() {    long totalSpace = 0;    if (!TextUtils.isEmpty(mSDCardPath)) {      StatFs sf = new StatFs(mSDCardPath);      long blockSize = sf.getBlockSize();      long total = sf.getBlockCount();      totalSpace = total * blockSize / 1024;    }    return totalSpace;  }  public long getSDCardAvailSpace() {    long availSpace = 0;    if (!TextUtils.isEmpty(mSDCardPath)) {      StatFs sf = new StatFs(mSDCardPath);      long blockSize = sf.getBlockSize();      long availCount = sf.getAvailableBlocks();      availSpace = availCount * blockSize / 1024;    }    return availSpace;  }  public String getInternalSDCardPath() {    return mInternalPathList.peek();  }  public String getExternalSDCardPath() {    return mExternalPathList.peek();  }  private void executeInit(Context context) {    StorageManager mStorageManager = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE);    if (mStorageManager != null) {      Class<?> mStorageVolume = null;      Method mGetVolumeListMethod = null;      Method mGetVolumeStateMethod = null;      Method mGetPathMethod = null;      Method mIsRemovableMethod = null;      Object[] mStorageVolumeList = null;      try {        mStorageVolume = Class.forName(CLASS_NAME);        mGetVolumeListMethod = mStorageManager.getClass().getMethod(METHOD_GET_VOLUME_LIST, new Class[0]);        mGetVolumeStateMethod = mStorageManager.getClass().getMethod(METHOD_GET_VOLUME_STATE, new Class[]{String.class});        mIsRemovableMethod = mStorageVolume.getMethod(METHOD_IS_REMOVABLE, new Class[0]);        mGetPathMethod = mStorageVolume.getMethod(METHOD_GET_PATH, new Class[0]);        mStorageVolumeList = (Object[]) mGetVolumeListMethod.invoke(mStorageManager, new Object[0]);        boolean mIsRemovable = false;        if (mStorageVolumeList != null && mStorageVolumeList.length > 0) {          int mStorageVolumeCount = mStorageVolumeList.length;          Log.i(TAG, "init() === > StorageVolume Count = " + mStorageVolumeCount);          mInternalPathList.clear();          mExternalPathList.clear();          for (int i = 0; i < mStorageVolumeCount; ++i) {            String mStoragePath = (String) mGetPathMethod.invoke(mStorageVolumeList[i], new Object[0]);            mIsRemovable = ((Boolean) mIsRemovableMethod.invoke(mStorageVolumeList[i], new Object[0])).booleanValue();            if (!TextUtils.isEmpty(mStoragePath)) {              String state = (String) mGetVolumeStateMethod.invoke(mStorageManager, new Object[]{mStoragePath});              if ((state != null) && (state.equals(MOUNTED))) {                if (mIsRemovable) {                  Log.i(TAG, "init() === > external storage path = (" + mStoragePath + ")");                  mExternalPathList.add(mStoragePath);                } else {                  Log.i(TAG, "init() === > internal storage path = (" + mStoragePath + ")");                  mInternalPathList.add(mStoragePath);                }              }            }          }        }      } catch (ClassNotFoundException e) {        handleInvalid();        Log.e(TAG, "init() === > Exception:ClassNotFoundException");      } catch (NoSuchMethodException e) {        handleInvalid();        Log.e(TAG, "init() === > Exception:NoSuchMethodException");      } catch (IllegalArgumentException e) {        handleInvalid();        Log.e(TAG, "init() === > Exception:IllegalArgumentException");      } catch (IllegalAccessException e) {        handleInvalid();        Log.e(TAG, "init() === > Exception:IllegalAccessException");      } catch (InvocationTargetException e) {        handleInvalid();        Log.e(TAG, "init() === > Exception:InvocationTargetException");      }    } else {      handleInvalid();      Log.e(TAG, "init() === > can't get storage manager");    }    initSDCardPath();  }  private void handleInvalid() {    mInternalPathList.add(Environment.getExternalStorageDirectory().getPath());  }  private void initSDCardPath() {    if (!mExternalPathList.isEmpty()) {      mSDCardPath = mExternalPathList.peek();    } else if (!mInternalPathList.isEmpty()) {      mSDCardPath = mInternalPathList.peek();    } else {      mSDCardPath = Environment.getExternalStorageDirectory().getPath();    }    Log.i(TAG, "initSDCardPath() === > SDCARD PATH = (" + mSDCardPath + ")");  }  /**   * SDCARD是否存   */  public static boolean externalMemoryAvailable() {    return android.os.Environment.getExternalStorageState().equals(        android.os.Environment.MEDIA_MOUNTED);  }  /**   * 獲取手機內部剩余存儲空間   *   * @return   */  public static long getAvailableInternalMemorySize() {    File path = Environment.getDataDirectory();    StatFs stat = new StatFs(path.getPath());    long blockSize = stat.getBlockSize();    long availableBlocks = stat.getAvailableBlocks();    return availableBlocks * blockSize;  }  /**   * 獲取手機內部總的存儲空間   *   * @return   */  public static long getTotalInternalMemorySize() {    File path = Environment.getDataDirectory();    StatFs stat = new StatFs(path.getPath());    long blockSize = stat.getBlockSize();    long totalBlocks = stat.getBlockCount();    return totalBlocks * blockSize;  }  /**   * 獲取手機內置存儲剩余存儲空間   *   * @return   */  public static long getAvailableInternalSystemMemorySize() {    File path = Environment.getRootDirectory();    StatFs stat = new StatFs(path.getPath());    long blockSize = stat.getBlockSize();    long availableBlocks = stat.getAvailableBlocks();    return availableBlocks * blockSize;  }  /**   * 獲取手機內置存儲總的存儲空間   *   * @return   */  public static long getTotalInternalSystemMemorySize() {    File path = Environment.getRootDirectory();    StatFs stat = new StatFs(path.getPath());    long blockSize = stat.getBlockSize();    long totalBlocks = stat.getBlockCount();    return totalBlocks * blockSize;  }  /**   * 獲取SDCARD剩余存儲空間   *   * @return   */  public static long getAvailableExternalMemorySize() {    if (externalMemoryAvailable()) {      File path = Environment.getExternalStorageDirectory();      StatFs stat = new StatFs(path.getPath());      long blockSize = stat.getBlockSize();      long availableBlocks = stat.getAvailableBlocks();      return availableBlocks * blockSize;    } else {      return ERROR;    }  }  /**   * 獲取SDCARD總的存儲空間   *   * @return   */  public static long getTotalExternalMemorySize() {    if (externalMemoryAvailable()) {      File path = Environment.getExternalStorageDirectory();      StatFs stat = new StatFs(path.getPath());      long blockSize = stat.getBlockSize();      long totalBlocks = stat.getBlockCount();      return totalBlocks * blockSize;    } else {      return ERROR;    }  }  public static long getAvailableMemorySize(String path) {    if (null == path)      return 0;    StatFs stat = new StatFs(path);    long blockSize = stat.getBlockSize();    long availableBlocks = stat.getAvailableBlocks();    return availableBlocks * blockSize;  }}

讀取raw和assets文件夾下的文件

相信大家對兩個文件夾并不陌生,如果我們不想自己的文件被編譯成二進制文件的話, 我們可以把文件放到這兩個目錄下,而兩者的區別如下:

  • res/raw:文件會被映射到R.java文件中,訪問的時候直接通過資源ID即可訪問,而且 他不能有目錄結構,就是不能再創建文件夾
  • assets:不會映射到R.java文件中,通過AssetManager來訪問,能有目錄結構,即, 可以自行創建文件夾。

讀取文件資源:

res/raw:

InputStream is =getResources().openRawResource(R.raw.filename); 

assets:

AssetManager am = getAssets(); InputStream is = am.open("filename");

SAX引擎讀取XML文件

sax引擎讀取xml文件的原理:

sax技術在處理xml文件時并不一次性把xml文件裝入內存,而是一邊讀一般解析。

使用sax處理xml需要一個Handler對象,一般會使用org.xml.sax.helpers.DefaultHandler的子類作為Handler對象

因此,這就需要處理如下5個分析點,也可稱為分析事件:

  1. 開始分析xml文件。該分析點表示sax引擎剛開始處理xml文件,還沒有讀取xml文件中的內容。該分析點對應于DefaultHandler類中的startDocument()事件方法,可以在該方法中做一下初始化的工作!
  2. 開始處理每一個xml元素,也就是遇到<product>,<item>這樣的起始標記,sax引擎每次掃描到新的xml元素的起始標記會觸發這個分析事件,對應的事件分析方法是startElement,在該方法中可以獲取當前元素的名稱和元素屬性的相關信息
  3. 處理完一個xml元素,也就是遇到</product>,</item>這樣的結束標記,該分析點對應的事件方法是endElement,在該事件中可以獲得當前處理完的元素的全部信息。
  4. 處理完xml文件。如果sax引擎將整個xml文件的內容都掃描完了,就到了這個分析點,該分析點對應的事件方法endDocument(),該事件方法可能不是必需的,如果最后有以下收尾工作,如釋放一下資源,可以在該方法中完成!
  5. 讀取字符分析點。這是最重要的分析點。如果沒有這個分析點,前4步的處理相當于白跑一遍,雖然讀取了xml文件中的所有內容,但并未保存這些內容,而這個分析點所對應的characters事件方法的主要作用就是保存sax引擎讀取的xml文件中的內容。更準確地說是保存xml元素的文本,也就是<product>abc</product>中的abc。

Code

res/raw/product.xml

<?xml version="1.0" encoding="utf-8"?><products>  <product>    <id>10</id>    <name>電腦</name>    <price>2067.25</price>  </product>  <product>    <id>20</id>    <name>微波爐</name>    <price>520</price>  </product>  <product>    <id>30</id>    <name>洗衣機</name>    <price>2400</price>  </product></products>

Product.java

public class Product{  private int id;  private String name;  private float price;  public int getId()  {    return id;  }  public void setId(int id)  {    this.id = id;  }  public String getName()  {    return name;  }  public void setName(String name)  {    this.name = name;  }  public float getPrice()  {    return price;  }  public void setPrice(float price)  {    this.price = price;  }}

XML2Product.java(DefaultHandler子類)

DefaultHandler子類 ,核心類,負責處理分析點事件。

import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;import java.util.ArrayList;import java.util.List;public class XML2Product extends DefaultHandler {  private List<Product> products;  private Product product;  private StringBuffer buffer = new StringBuffer();  public List<Product> getProducts() {    return products;  }  @Override  public void characters(char[] ch, int start, int length)      throws SAXException {    buffer.append(ch, start, length);    super.characters(ch, start, length);  }  @Override  public void startDocument() throws SAXException {    // 開始分析xml文件,創建List對象用于保存分析完的Product對象    products = new ArrayList<Product>();  }  @Override  public void startElement(String uri, String localName, String qName,               Attributes attributes) throws SAXException {    if (localName.equals("product")) {      // 如果分析的是<product>標簽,則創建一個Product對象      product = new Product();    }    super.startElement(uri, localName, qName, attributes);  }  @Override  public void endElement(String uri, String localName, String qName)      throws SAXException {    if (localName.equals("product")) {      // 處理完 <product>標簽后 將product對象添加到products中      products.add(product);    } else if (localName.equals("id")) {      // 設置id屬性的值      product.setId(Integer.parseInt(buffer.toString().trim()));      // 將標簽內容的緩存區清空      buffer.setLength(0);    } else if (localName.equals("name")) {      product.setName(buffer.toString().trim());      buffer.setLength(0);    } else if (localName.equals("price")) {      product.setPrice(Float.parseFloat(buffer.toString().trim()));      buffer.setLength(0);    }    super.endElement(uri, localName, qName);  }}

Xml2JavaObjectAct

import android.app.AlertDialog;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.util.Xml;import android.view.View;import com.turing.base.R;import java.io.InputStream;import java.util.List;public class Xml2JavaObjectAct extends AppCompatActivity {  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_xml2_java_object);  }  public void onClick_XMLToObject(View view) {    try {      // 打開資源文件      InputStream is = getResources().openRawResource(R.raw.products);      XML2Product xml2Product = new XML2Product();      // 開始分析priducts.xml文件      android.util.Xml.parse(is, Xml.Encoding.UTF_8, xml2Product);      // 輸出轉換后的java對象      List<Product> products = xml2Product.getProducts();      String msg = "共" + products.size() + "個產品/n";      for (Product product : products) {        msg += "id:" + product.getId() + " 產品名:" + product.getName()            + " 價格:" + product.getPrice() + "/n";      }      // 彈出對話框      new AlertDialog.Builder(this).setTitle("產品信息").setMessage(msg)          .setPositiveButton("關閉", null).show();    } catch (Exception e) {    }  }}

效果圖

Code

activity_jar_zip.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:layout_width="fill_parent"  android:layout_height="fill_parent"  android:orientation="vertical" >  <Button    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:onClick="onClick_Jar_Compress"    android:text="用jar格式壓縮文件" />  <Button    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:onClick="onClick_Jar_Uncompress"    android:text="解壓jar格式文件" />  <Button    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:onClick="onClick_Zip_Compress"    android:text="用zip格式壓縮文件" />  <Button    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:onClick="onClick_Zip_Uncompress"    android:text="解壓zip格式文件" /></LinearLayout>

JarZipAct

import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Toast;import com.turing.base.R;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.InputStream;import java.util.jar.JarEntry;import java.util.jar.JarInputStream;import java.util.jar.JarOutputStream;import java.util.zip.ZipEntry;import java.util.zip.ZipInputStream;import java.util.zip.ZipOutputStream;public class JarZipAct extends AppCompatActivity {  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_jar_zip);  }  public void onClick_Jar_Compress(View view) {    try {      // 使用FileOutputStream對象指定一個要輸出的壓縮文件(file.jar)      FileOutputStream fos = new FileOutputStream(          android.os.Environment.getExternalStorageDirectory()              + "/file.jar");      // 第一步 創建JarOutputStream對象      JarOutputStream jos = new JarOutputStream(fos);      // 第二步 創建一個JarEntry對象,并指定待壓縮文件在壓縮包中的文件名      JarEntry jarEntry = new JarEntry("strings.xml");      jos.putNextEntry(jarEntry);      InputStream is = getResources().getAssets().open("strings.xml");      byte[] buffer = new byte[8192];      int count = 0;      // 第四步 寫入數據      while ((count = is.read(buffer)) >= 0) {        jos.write(buffer, 0, count);      }      // 第五步 關閉當前的JarEntry等對象      is.close();      jos.closeEntry();      jos.close();      Toast.makeText(this, "成功將strings.xml文件以jar格式壓縮.", Toast.LENGTH_LONG)          .show();    } catch (Exception e) {      Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();    }  }  public void onClick_Jar_Uncompress(View view) {    try {      // 定義要解壓的文件      String filename = android.os.Environment          .getExternalStorageDirectory() + "/file.jar";      if (!new File(filename).exists()) {        Toast.makeText(this, "壓縮文件不存在.", Toast.LENGTH_LONG).show();        return;      }      // 使用FileInputStream對象指定要解壓的對象      FileInputStream fis = new FileInputStream(filename);      // 1 創建JarInputStream對象來讀取壓縮文件(file.jar)      JarInputStream jis = new JarInputStream(fis);      // 2 調用getNextJarEntry方法打開壓縮包中的第一個文件 ,如果有多個,多次調用該方法      JarEntry jarEntry = jis.getNextJarEntry();      // 3 輸出已解壓的文件      FileOutputStream fos = new FileOutputStream(          android.os.Environment.getExternalStorageDirectory()              + "/" + jarEntry.getName());      byte[] buffer = new byte[8192];      int count = 0;      // 4 輸出已解壓的字節流      while ((count = jis.read(buffer)) >= 0) {        fos.write(buffer, 0, count);      }      // 5 關閉      jis.closeEntry();      jis.close();      fos.close();      Toast.makeText(this, "成功解壓jar格式的文件.", Toast.LENGTH_LONG).show();    } catch (Exception e) {      Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();    }  }  public void onClick_Zip_Compress(View view) {    try {      // 指定了2個待壓縮的w文件,都在assets目錄中      String[] filenames = new String[]          {"main.xml", "strings.xml"};      FileOutputStream fos = new FileOutputStream(          android.os.Environment.getExternalStorageDirectory()              + "/file.zip");      ZipOutputStream zos = new ZipOutputStream(fos);      int i = 1;      //枚舉filenames中的所有待壓縮文件      while (i <= filenames.length) {        // 從filenames數組中取出當前待壓縮的溫佳明,作為壓縮后的文件名,以保持要說前后文件名稱一致        ZipEntry zipEntry = new ZipEntry(filenames[i - 1]);        // 打開當前的ZipEntry對象        zos.putNextEntry(zipEntry);        InputStream is = getResources().getAssets().open(            filenames[i - 1]);        byte[] buffer = new byte[8192];        int count = 0;        // 寫入數據        while ((count = is.read(buffer)) >= 0) {          zos.write(buffer, 0, count);        }        zos.flush();        // 關閉當前的ZipEntry對象        zos.closeEntry();        is.close();        i++;      }      zos.finish();      zos.close();      Toast.makeText(this, "成功將main.xml、strings.xml文件以zip格式壓縮.",          Toast.LENGTH_LONG).show();    } catch (Exception e) {      Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();    }  }  public void onClick_Zip_Uncompress(View view) {    try {      // 指定待解壓的文件      String filename = android.os.Environment          .getExternalStorageDirectory() + "/file.zip";      if (!new File(filename).exists()) {        Toast.makeText(this, "壓縮文件不存在.", Toast.LENGTH_LONG).show();        return;      }      FileInputStream fis = new FileInputStream(filename);      ZipInputStream zis = new ZipInputStream(fis);      ZipEntry zipEntry = null;      // 通過不斷調用getNextEntry方法來解壓file.zip中所有的文件      while ((zipEntry = zis.getNextEntry()) != null) {        FileOutputStream fos = new FileOutputStream(            android.os.Environment.getExternalStorageDirectory()                + "/" + zipEntry.getName());        byte[] buffer = new byte[8192];        int count = 0;        while ((count = zis.read(buffer)) >= 0) {          fos.write(buffer, 0, count);        }        zis.closeEntry();        fos.close();      }      zis.close();      Toast.makeText(this, "成功解壓jar格式的文件.", Toast.LENGTH_LONG).show();    } catch (Exception e) {      Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();    }  }}

原文鏈接:http://blog.csdn.net/yangshangwei/article/details/50831269

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