概述

文件存取的核心就是输入流和输出流。

Android文件的操作模式

文件的相关操作方法

文件读写的实现

openFileOutput和openFileInput方法

  /**
     * openFIleOutput ,openFileInput
     * 这两种方法同sp一样只能讲文件保存到手机内存固定的路径中，
     * 默认为 /data/data/<packageName>/files
     */
    private void save2File() {
        try {
            //向文件写入内容
            FileOutputStream os = openFileOutput("file.txt", Context.MODE_PRIVATE);
            String text = "写数据到文件";
            os.write(text.getBytes("utf-8"));
            //关闭流
            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();
        }
    }

文件存储位置

/data/data/<package-name>/files目录下

openFileOutput和openFileInput方法可以获得操作文件的OutputStream以及InputStream对象，而且可以通过流对象处理任何文件的数据，但是这两个方法同SharedPreferences一样，只能在手机内存卡的指定目录建立文件，因此在使用上仍然有一定的局限性。

读取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="清输入文件名" />
    <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="清输入文件内容" />
    <EditText
        android:id="@+id/editdetail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="文件内容" />
    <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="读取sd卡中的文件" />
</LinearLayout>

接着我们来写一个SD操作类： SDFileHelper.java

public class SDFileHelper {
    private Context context;
    public SDFileHelper() {
    }
    public SDFileHelper(Context context) {
        super();
        this.context = context;
    }
    //往SD卡写入文件的方法
    public void savaFileToSD(String filename, String filecontent) throws Exception {
        //如果手机已插入sd卡,且app具有读写sd卡的权限
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            filename = Environment.getExternalStorageDirectory().getCanonicalPath() + "/" + filename;
            //这里就不要用openFileOutput了,那个是往手机内存中写数据的
            FileOutputStream output = new FileOutputStream(filename);
            output.write(filecontent.getBytes());
            //将String字符串以字节流的形式写入到输出流中
            output.close();
            //关闭输出流
        } else Toast.makeText(context, "SD卡不存在或者不可读写", Toast.LENGTH_SHORT).show();
    }
    //读取SD卡中文件的方法
    //定义读取文件的方法:
    public String readFromSD(String filename) throws IOException {
        StringBuilder sb = new StringBuilder("");
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            filename = Environment.getExternalStorageDirectory().getCanonicalPath() + "/" + filename;
            //打开文件输入流
            FileInputStream input = new FileInputStream(filename);
            byte[] temp = new byte[1024];
            int len = 0;
            //读取文件内容:
            while ((len = input.read(temp)) > 0) {
                sb.append(new String(temp, 0, len));
            }
            //关闭输入流
            input.close();
        }
        return sb.toString();
    }
}

接着MainActivity.java实现相关逻辑：

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(), "数据写入成功", Toast.LENGTH_SHORT).show();
                }
                catch(Exception e){
                    e.printStackTrace();
                    Toast.makeText(getApplicationContext(), "数据写入失败", 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;
        }
    }
}

最后别忘记在AndroidManifest.xml写上读写SD卡的权限哦！

<!-- 在SDCard中创建与删除文件权限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!-- 往SDCard写入数据权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

如何判断虚拟和物理两种SDK

在默认情况下，会将一部分存储空间分给虚拟的SD卡使用（一部分用于安装Android操作系统）

android.os.Enviroment.isExternalStorageRemovalbe()

返回true：SD卡是物理的，反之SD卡是虚拟的。

用于适配不同型号手机，反射获取SD卡路径和状态

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;
/**
 * 用于适配不同型号手机，反射获取SD卡路径和状态
 *
 */
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);
    }
    /**
     * 获取手机内部剩余存储空间
     *
     * @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;
    }
    /**
     * 获取手机内部总的存储空间
     *
     * @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;
    }
    /**
     * 获取手机内置存储剩余存储空间
     *
     * @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;
    }
    /**
     * 获取手机内置存储总的存储空间
     *
     * @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;
    }
    /**
     * 获取SDCARD剩余存储空间
     *
     * @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;
        }
    }
    /**
     * 获取SDCARD总的存储空间
     *
     * @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;
    }
}

读取raw和assets文件夹下的文件

相信大家对两个文件夹并不陌生，如果我们不想自己的文件被编译成二进制文件的话，我们可以把文件放到这两个目录下，而两者的区别如下：

res/raw：文件会被映射到R.java文件中，访问的时候直接通过资源ID即可访问，而且他不能有目录结构，就是不能再创建文件夹
assets：不会映射到R.java文件中，通过AssetManager来访问，能有目录结构，即，可以自行创建文件夹。

读取文件资源：

res/raw：

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

assets：

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

SAX引擎读取XML文件

sax引擎读取xml文件的原理：

sax技术在处理xml文件时并不一次性把xml文件装入内存，而是一边读一般解析。

使用sax处理xml需要一个Handler对象，一般会使用org.xml.sax.helpers.DefaultHandler的子类作为Handler对象

因此,这就需要处理如下5个分析点,也可称为分析事件:

开始分析xml文件。该分析点表示sax引擎刚开始处理xml文件，还没有读取xml文件中的内容。该分析点对应于DefaultHandler类中的startDocument()事件方法，可以在该方法中做一下初始化的工作！

开始处理每一个xml元素，也就是遇到<product>，<item>这样的起始标记，sax引擎每次扫描到新的xml元素的起始标记会触发这个分析事件，对应的事件分析方法是startElement，在该方法中可以获取当前元素的名称和元素属性的相关信息

处理完一个xml元素，也就是遇到</product>，</item>这样的结束标记，该分析点对应的事件方法是endElement，在该事件中可以获得当前处理完的元素的全部信息。

处理完xml文件。如果sax引擎将整个xml文件的内容都扫描完了，就到了这个分析点，该分析点对应的事件方法endDocument()，该事件方法可能不是必需的，如果最后有以下收尾工作，如释放一下资源，可以在该方法中完成！

读取字符分析点。这是最重要的分析点。如果没有这个分析点，前4步的处理相当于白跑一遍，虽然读取了xml文件中的所有内容，但并未保存这些内容，而这个分析点所对应的characters事件方法的主要作用就是保存sax引擎读取的xml文件中的内容。更准确地说是保存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>电脑</name>
        <price>2067.25</price>
    </product>
    <product>
        <id>20</id>
        <name>微波炉</name>
        <price>520</price>
    </product>
    <product>
        <id>30</id>
        <name>洗衣机</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子类)

DefaultHandler子类，核心类，负责处理分析点事件。

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 {
        // 开始分析xml文件,创建List对象用于保存分析完的Product对象
        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>标签，则创建一个Product对象
            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")) {
            // 处理完 <product>标签后 将product对象添加到products中
            products.add(product);
        } else if (localName.equals("id")) {
            // 设置id属性的值
            product.setId(Integer.parseInt(buffer.toString().trim()));
            // 将标签内容的缓存区清空
            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 {
            //  打开资源文件
            InputStream is = getResources().openRawResource(R.raw.products);
            XML2Product xml2Product = new XML2Product();
            // 开始分析priducts.xml文件
            android.util.Xml.parse(is, Xml.Encoding.UTF_8, xml2Product);
            // 输出转换后的java对象
            List<Product> products = xml2Product.getProducts();
            String msg = "共" + products.size() + "个产品\n";
            for (Product product : products) {
                msg += "id:" + product.getId() + "  产品名：" + product.getName()
                        + "  价格：" + product.getPrice() + "\n";
            }
            // 弹出对话框
            new AlertDialog.Builder(this).setTitle("产品信息").setMessage(msg)
                    .setPositiveButton("关闭", null).show();
        } catch (Exception e) {
        }
    }
}

效果图

文件的压缩（Jar，Zip）

效果图

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格式压缩文件" />
    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="onClick_Jar_Uncompress"
        android:text="解压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格式压缩文件" />
    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="onClick_Zip_Uncompress"
        android:text="解压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对象指定一个要输出的压缩文件(file.jar)
            FileOutputStream fos = new FileOutputStream(
                    android.os.Environment.getExternalStorageDirectory()
                            + "/file.jar");
            // 第一步 创建JarOutputStream对象
            JarOutputStream jos = new JarOutputStream(fos);
            // 第二步 创建一个JarEntry对象，并指定待压缩文件在压缩包中的文件名
            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 写入数据
            while ((count = is.read(buffer)) >= 0) {
                jos.write(buffer, 0, count);
            }
            // 第五步 关闭当前的JarEntry等对象
            is.close();
            jos.closeEntry();
            jos.close();
            Toast.makeText(this, "成功将strings.xml文件以jar格式压缩.", Toast.LENGTH_LONG)
                    .show();
        } catch (Exception e) {
            Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();
        }
    }
    public void onClick_Jar_Uncompress(View view) {
        try {
            // 定义要解压的文件
            String filename = android.os.Environment
                    .getExternalStorageDirectory() + "/file.jar";
            if (!new File(filename).exists()) {
                Toast.makeText(this, "压缩文件不存在.", Toast.LENGTH_LONG).show();
                return;
            }
            //  使用FileInputStream对象指定要解压的对象
            FileInputStream fis = new FileInputStream(filename);
            // 1 创建JarInputStream对象来读取压缩文件（file.jar）
            JarInputStream jis = new JarInputStream(fis);
            // 2 调用getNextJarEntry方法打开压缩包中的第一个文件 ，如果有多个，多次调用该方法
            JarEntry jarEntry = jis.getNextJarEntry();
            // 3 输出已解压的文件
            FileOutputStream fos = new FileOutputStream(
                    android.os.Environment.getExternalStorageDirectory()
                            + "/" + jarEntry.getName());
            byte[] buffer = new byte[8192];
            int count = 0;
            // 4 输出已解压的字节流
            while ((count = jis.read(buffer)) >= 0) {
                fos.write(buffer, 0, count);
            }
            // 5 关闭
            jis.closeEntry();
            jis.close();
            fos.close();
            Toast.makeText(this, "成功解压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个待压缩的w文件，都在assets目录中
            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;
            //枚举filenames中的所有待压缩文件
            while (i <= filenames.length) {
                // 从filenames数组中取出当前待压缩的温佳明，作为压缩后的文件名,以保持要说前后文件名称一致
                ZipEntry zipEntry = new ZipEntry(filenames[i - 1]);
                // 打开当前的ZipEntry对象
                zos.putNextEntry(zipEntry);
                InputStream is = getResources().getAssets().open(
                        filenames[i - 1]);
                byte[] buffer = new byte[8192];
                int count = 0;
                // 写入数据
                while ((count = is.read(buffer)) >= 0) {
                    zos.write(buffer, 0, count);
                }
                zos.flush();
                // 关闭当前的ZipEntry对象
                zos.closeEntry();
                is.close();
                i++;
            }
            zos.finish();
            zos.close();
            Toast.makeText(this, "成功将main.xml、strings.xml文件以zip格式压缩.",
                    Toast.LENGTH_LONG).show();
        } catch (Exception e) {
            Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();
        }
    }
    public void onClick_Zip_Uncompress(View view) {
        try {
            // 指定待解压的文件
           String filename = android.os.Environment
                    .getExternalStorageDirectory() + "/file.zip";
            if (!new File(filename).exists()) {
                Toast.makeText(this, "压缩文件不存在.", Toast.LENGTH_LONG).show();
                return;
            }
            FileInputStream fis = new FileInputStream(filename);
            ZipInputStream zis = new ZipInputStream(fis);
            ZipEntry zipEntry = null;
            // 通过不断调用getNextEntry方法来解压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, "成功解压jar格式的文件.", Toast.LENGTH_LONG).show();
        } catch (Exception e) {
            Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();
        }
    }
}

数据存储之文件存储

概述

Android文件的操作模式

文件的相关操作方法

文件读写的实现

openFileOutput和openFileInput方法

文件存储位置

读取SD卡上的文件

如何判断虚拟和物理两种SDK

用于适配不同型号手机，反射获取SD卡路径和状态

读取raw和assets文件夹下的文件

SAX引擎读取XML文件

sax引擎读取xml文件的原理：

Code

res\raw\product.xml

Product.java

XML2Product.java(DefaultHandler子类)

Xml2JavaObjectAct

效果图

文件的压缩（Jar，Zip）

效果图

Code

activity_jar_zip.xml

JarZipAct

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