【Android】文件读写及文件下载操作

package demo.filerw.service;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import android.content.Context;
import android.os.Environment;
/**
* 文件操作类
* @author janrone
* @website http://hujl.sinaapp.com */
public class FileService {
private Context context;
public FileService(Context context) {
this.context = context;
}
//存储数据到文件
public void saveName(String name) throws Exception{
//context.getFilesDir();// 得到存放文件的系统目录 /data/data/<package name>/files
//context.getCacheDir(); //缓存目录  /data/data/<package name>/cache
FileOutputStream outputStream=context.openFileOutput(“deomfilerw.txt”, Context.MODE_APPEND);
outputStream.write(name.getBytes());
outputStream.close();
}
//存储数据到sdcard
public void saveNameToSDCard(String name) throws Exception{
Environment.getExternalStorageDirectory(); //得到sdcard目录
File file=new File(“/sdcard”,”demosdcard.txt”);
FileOutputStream outputStream=new FileOutputStream(file);
outputStream.write(name.getBytes());
outputStream.close();
}
// 读取数据
public String getName() throws Exception{
FileInputStream inputStream=context.openFileInput(“deomfilerw.txt”);
ByteArrayOutputStream outStream=new ByteArrayOutputStream();
byte[] buffer=new byte[1024];
int len=0;
while ((len=inputStream.read(buffer))!=-1){
outStream.write(buffer, 0, len);
}
outStream.close();
byte[] data=outStream.toByteArray();
String name=new String(data);
return name;
}
}

mWebView.setDownloadListener(new DownloadListener(){//监听下载
public void onDownloadStart(String url, String userAgent, String contentDisposition,String mimetype, long contentLength)
{
Toast.makeText(MainActivity.this,"下载中", Toast.LENGTH_SHORT).show();
downloadFile(url, mimetype, mimetype, mimetype, contentLength);

}

});
}
private void downloadFile(String url,String userAgent, String contentDisposition,String mimetype, long contentLength) {
FileOutputStream fos;
boolean hasSD = Environment.getExternalStorageState().equals( android.os.Environment.MEDIA_MOUNTED); //是否存在SD卡
Toast.makeText(MainActivity.this,"下载中开始", Toast.LENGTH_SHORT).show();
String filename =URLUtil.guessFileName(url,contentDisposition, mimetype);
try {
if(hasSD)
{
File fileName=new File( Environment.getExternalStorageDirectory().getPath(),filename);
fos = new FileOutputStream(fileName);
}
else
{
fos = this.openFileOutput(filename, Context.MODE_APPEND);
}

URL url2 = new URL(url);
HttpURLConnection conn = (HttpURLConnection) url2.openConnection();
conn.setDoInput(true);
conn.connect();
if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
InputStream is = conn.getInputStream();

int len = 0;
byte[] buf = new byte[1024];
while ((len = is.read(buf)) != -1) {
fos.write(buf, 0, len);
}
is.close();
fos.close();
Toast.makeText(MainActivity.this,"结束"+filename, Toast.LENGTH_SHORT).show();
} else {

Toast.makeText(MainActivity.this,"下载错误", Toast.LENGTH_SHORT).show();

}
} catch (Exception e) {
Toast.makeText(MainActivity.this,"下载有错"+e.toString(), Toast.LENGTH_SHORT).show();
}

}