android(6)(读数据的一些权限)
16lz
2021-01-23
读数据的权限:public class MainActivity extends Activity implements OnClickListener { private String basicPath = "/data/data/com.itheima.writedata/files/"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); findViewById(R.id.btn_read_private).setOnClickListener(this); findViewById(R.id.btn_write_private).setOnClickListener(this); findViewById(R.id.btn_read_readable).setOnClickListener(this); findViewById(R.id.btn_write_readable).setOnClickListener(this); findViewById(R.id.btn_read_writeable).setOnClickListener(this); findViewById(R.id.btn_write_writeable).setOnClickListener(this); findViewById(R.id.btn_read_readable_writeable).setOnClickListener(this); findViewById(R.id.btn_write_readable_writeable).setOnClickListener(this); } /** * 哪一个控件被点击, v对象就代表被点击的对象 */ @Override public void onClick(View v) { switch (v.getId()) { case R.id.btn_read_private: readFile("private.txt"); break; case R.id.btn_write_private: writeFile("private.txt"); break; case R.id.btn_read_readable: readFile("readable.txt"); break; case R.id.btn_write_readable: writeFile("readable.txt"); break; case R.id.btn_read_writeable: readFile("writeable.txt"); break; case R.id.btn_write_writeable: writeFile("writeable.txt"); break; case R.id.btn_read_readable_writeable: readFile("readable_writeable.txt"); break; case R.id.btn_write_readable_writeable: writeFile("readable_writeable.txt"); break; default: break; } } /** * 读文件 * @param fileName */ private void readFile(String fileName) { try { String path = basicPath + fileName; BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(path))); String text = reader.readLine(); reader.close(); Toast.makeText(this, "读取成功: " + text, 0).show(); } catch (Exception e) { e.printStackTrace(); Toast.makeText(this, "读取失败: " + fileName, 0).show(); } } /** * 写文件 * @param fileName */ private void writeFile(String fileName) { try { String path = basicPath + fileName; FileOutputStream fos = new FileOutputStream(path); fos.write("哈哈, 被我给黑了".getBytes()); fos.flush(); fos.close(); Toast.makeText(this, "写入成功: " + fileName, 0).show(); } catch (Exception e) { e.printStackTrace(); Toast.makeText(this, "写入失败: " + fileName, 0).show(); } }2.Linux权限:- --- --- ---总共十位,第一位:代表文件类型(d:文件夹;-:文件;l:挂载某一个文件) 第2-4位:rw-:代表的是当前用户的权限。110=6. 第5-7位:当前用户所在组的其他组员的权限 第8-10位:其他所有的权限 ---没有任何权限,r--可读,-w-可写,rw-可读可写。 改变某一个文件的权限:change mode = chmod chmod 666 private.txt
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