本文介绍如何使用内置的Java API编写实用程序类，从压缩的zip归档文件中提取文件和目录。
java.util.zip包提供以下类来从ZIP存档文件中提取文件和目录：
ZipInputStream：这是主要的类，可用于读取zip文件并提取归档文件中的文件和目录（条目）。以下是此类的一些重要用法：
- 通过其构造函数ZipInputStream（FileInputStream）读取zip文件
- 通过方法getNextEntry（）读取文件和目录的条目
- 通过方法read（byte）读取当前条目的二进制数据
- 通过方法closeEntry（）关闭当前条目
- 通过方法close（）关闭zip文件
ZipEntry：此类表示zip文件中的条目。每个文件或目录都表示为ZipEntry对象。它的方法getName（）返回一个字符串，表示文件/目录的路径。路径的格式如下：
folder_1/subfolder_1/subfolder_2/…/subfolder_n/file.ext
根据ZipEntry的路径，在提取zip文件时重新创建目录结构。
下面的类用于解压下载的zip文件并提取文件并将其存储在所需位置。
public class UnzipUtil
{
private String zipFile;
private String location;
public UnzipUtil(String zipFile, String location)
{
this.zipFile = zipFile;
this.location = location;
dirChecker("");
}
public void unzip()
{
try
{
FileInputStream fin = new FileInputStream(zipFile);
ZipInputStream zin = new ZipInputStream(fin);
ZipEntry ze = null;
while ((ze = zin.getNextEntry()) != null)
{
Log.v("Decompress", "Unzipping " + ze.getName());
if(ze.isDirectory())
{
dirChecker(ze.getName());
}
else
{
FileOutputStream fout = new FileOutputStream(location + ze.getName());
byte[] buffer = new byte[8192];
int len;
while ((len = zin.read(buffer)) != -1)
{
fout.write(buffer, 0, len);
}
fout.close();
zin.closeEntry();
}
}
zin.close();
}
catch(Exception e)
{
Log.e("Decompress", "unzip", e);
}
}
private void dirChecker(String dir)
{
File f = new File(location + dir);
if(!f.isDirectory())
{
f.mkdirs();
}
}
}
MainActivity类:
public class MainActivity extends Activity
{
private ProgressDialog mProgressDialog;
String Url="http://hasmukh/hb.zip";
String unzipLocation = Environment.getExternalStorageDirectory() + "/unzipFolder/";
String StorezipFileLocation =Environment.getExternalStorageDirectory() + "/DownloadedZip";
String DirectoryName=Environment.getExternalStorageDirectory() + "/unzipFolder/files/";
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
DownloadZipfile mew = new DownloadZipfile();
mew.execute(url);
}
class DownloadZipfile extends AsyncTask<String, String, String>
{
String result ="";
@Override
protected void onPreExecute()
{
super.onPreExecute();
mProgressDialog = new ProgressDialog(MainActivity.this);
mProgressDialog.setMessage("Downloading...");
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
mProgressDialog.setCancelable(false);
mProgressDialog.show();
}
@Override
protected String doInBackground(String... aurl)
{
int count;
try
{
URL url = new URL(aurl[0]);
URLConnection conexion = url.openConnection();
conexion.connect();
int lenghtOfFile = conexion.getContentLength();
InputStream input = new BufferedInputStream(url.openStream());
OutputStream output = new FileOutputStream(StorezipFileLocation);
byte data[] = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1)
{
total += count;
publishProgress(""+(int)((total*100)/lenghtOfFile));
output.write(data, 0, count);
}
output.close();
input.close();
result = "true";
} catch (Exception e) {
result = "false";
}
return null;
}
protected void onProgressUpdate(String... progress)
{
Log.d("ANDRO_ASYNC",progress[0]);
mProgressDialog.setProgress(Integer.parseInt(progress[0]));
}
@Override
protected void onPostExecute(String unused)
{
mProgressDialog.dismiss();
if(result.equalsIgnoreCase("true"))
{
try
{
unzip();
} catch (IOException e)
{
e.printStackTrace();
}
}
else
{
}
}
}
public void unzip() throws IOException
{
mProgressDialog = new ProgressDialog(MainActivity.this);
mProgressDialog.setMessage("Please Wait...");
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
mProgressDialog.setCancelable(false);
mProgressDialog.show();
new UnZipTask().execute(StorezipFileLocation, DirectoryName);
}
private class UnZipTask extends AsyncTask<String, Void, Boolean>
{
@SuppressWarnings("rawtypes")
@Override
protected Boolean doInBackground(String... params)
{
String filePath = params[0];
String destinationPath = params[1];
File archive = new File(filePath);
try
{
ZipFile zipfile = new ZipFile(archive);
for (Enumeration e = zipfile.entries(); e.hasMoreElements();)
{
ZipEntry entry = (ZipEntry) e.nextElement();
unzipEntry(zipfile, entry, destinationPath);
}
UnzipUtil d = new UnzipUtil(StorezipFileLocation, DirectoryName);
d.unzip();
}
catch (Exception e)
{
return false;
}
return true;
}
@Override
protected void onPostExecute(Boolean result)
{
mProgressDialog.dismiss();
}
private void unzipEntry(ZipFile zipfile, ZipEntry entry,String outputDir) throws IOException
{
if (entry.isDirectory())
{
createDir(new File(outputDir, entry.getName()));
return;
}
File outputFile = new File(outputDir, entry.getName());
if (!outputFile.getParentFile().exists())
{
createDir(outputFile.getParentFile());
}
BufferedInputStream inputStream = new BufferedInputStream(zipfile.getInputStream(entry));
BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(outputFile));
try
{
}
finally
{
outputStream.flush();
outputStream.close();
inputStream.close();
}
}
private void createDir(File dir)
{
if (dir.exists())
{
return;
}
if (!dir.mkdirs())
{
throw new RuntimeException("Can not create dir " + dir);
}
}}
}
Note: Do not forgot to add below permission in android Manifest.xml file.
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" ></uses-permission>
<uses-permission android:name="android.permission.INTERNET" />
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