Android学习笔记_59_清除sdcard缓存

　　对于手机来说，每个软件在安装时，都会在sdcard上创建一个目录，用于缓存文件。市场上针对这些软件，统一了它的sdcard上的目录，将缓存目录存放到数据库中。如果要清理，可以根据当前应用包的名称，到数据库去查询缓存路径，如果

到再进行递归删除它下的文件。

public class DemoActivity extends Activity {
private TextView tv;
private ProgressBar pb;
private SQLiteDatabase db;
private Handler handler = new Handler(){

@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
String text = (String) msg.obj;
tv.setText(text);
}

};

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
tv = (TextView) this.findViewById(R.id.tv);
pb = (ProgressBar) this.findViewById(R.id.progressBar1);

// 判断手机内存里面是否有数据库存在
File file = new File("/data/data/cn.itcast.clear/files/clearpath.db");
if (!file.exists()) {
copyfile();
}
// 文件写到哪里了?
// data/data/cn.itcast.clear/files/name

}

public void start(View view) {
db = SQLiteDatabase.openDatabase("/data/data/cn.itcast.clear/files/clearpath.db", null, SQLiteDatabase.OPEN_READONLY);
new Thread(){
@Override
public void run() {
List<PackageInfo> packinfos =    getPackageManager().getInstalledPackages(0);
pb.setMax(packinfos.size());// 设置进度条的最大条目个数
int total=0;
for(PackageInfo info : packinfos){
String packname = info.packageName;
Cursor curosr = db.rawQuery("select filepath from softdetail where apkname=?", new String[]{packname});
if(curosr.moveToFirst()){
String path = curosr.getString(0);
System.out.println("清除"+packname+"sd卡缓存"+path);
File file = new File(Environment.getExternalStorageDirectory(),path);
deleteDir(file);
try {
sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
total++;
pb.setProgress(total);
curosr.close();
Message msg = Message.obtain();
msg.obj = "清除"+packname;
handler.sendMessage(msg);
}

Message msg = Message.obtain();
msg.obj = "清除完毕";
handler.sendMessage(msg);
db.close();
}

}.start();
}

private void copyfile() {

try {
InputStream is = getClass().getClassLoader().getResourceAsStream(
"clearpath.db");
OutputStream fos =    this.openFileOutput("clearpath.db", MODE_PRIVATE);
byte[] buffer = new byte[1024];
int len = 0;

while ((len = is.read(buffer)) != -1) {
fos.write(buffer, 0, len);
}
fos.flush();
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}

　　//递归删除缓存文件夹下的文件
private void deleteDir(File file){
if(file.isDirectory()){
File[] files = file.listFiles();
for(int i=0;i<files.length;i++){
deleteDir(file);
}
}else{
file.delete();
}

}
}