问题
我在这里搜索并完成了大部分问题,但这些问题似乎都无法解决我的问题。
我想通过从EditText输入文本将文件保存到内部存储。然后我想要相同的文件以String形式返回输入的文本并将其保存到另一个稍后要使用的String。
这是代码:
package com.omm.easybalancerecharge;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.telephony.TelephonyManager;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText num = (EditText) findViewById(R.id.sNum);
Button ch = (Button) findViewById(R.id.rButton);
TelephonyManager operator = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
String opname = operator.getNetworkOperatorName();
TextView status = (TextView) findViewById(R.id.setStatus);
final EditText ID = (EditText) findViewById(R.id.IQID);
Button save = (Button) findViewById(R.id.sButton);
final String myID = ""; //When Reading The File Back, I Need To Store It In This String For Later Use
save.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
//Get Text From EditText "ID" And Save It To Internal Memory
}
});
if (opname.contentEquals("zain SA")) {
status.setText("Your Network Is: " + opname);
} else {
status.setText("No Network");
}
ch.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
//Read From The Saved File Here And Append It To String "myID"
String hash = Uri.encode("#");
Intent intent = new Intent(Intent.ACTION_CALL);
intent.setData(Uri.parse("tel:*141*" + /*Use The String With Data Retrieved Here*/ num.getText()
+ hash));
startActivity(intent);
}
});
}
我已经包含了一些注释,可以帮助你进一步分析我的观点,即我希望在哪里进行操作/使用变量。
#1 热门回答(268 赞)
希望这可能对你有用。
写文件:
private void writeToFile(String data,Context context) {
try {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(context.openFileOutput("config.txt", Context.MODE_PRIVATE));
outputStreamWriter.write(data);
outputStreamWriter.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
阅读文件:
private String readFromFile(Context context) {
String ret = "";
try {
InputStream inputStream = context.openFileInput("config.txt");
if ( inputStream != null ) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String receiveString = "";
StringBuilder stringBuilder = new StringBuilder();
while ( (receiveString = bufferedReader.readLine()) != null ) {
stringBuilder.append(receiveString);
}
inputStream.close();
ret = stringBuilder.toString();
}
}
catch (FileNotFoundException e) {
Log.e("login activity", "File not found: " + e.toString());
} catch (IOException e) {
Log.e("login activity", "Can not read file: " + e.toString());
}
return ret;
}
#2 热门回答(142 赞)
对于那些寻找读取和写入字符串到文件的一般策略的人:
首先,获取文件对象
你需要存储路径。对于内部存储,请使用:
File path = context.getFilesDir();
对于外部存储(SD卡),请使用:
File path = context.getExternalFilesDir(null);
然后创建你的文件对象:
File file = new File(path, "my-file-name.txt");
写一个字符串到文件
FileOutputStream stream = new FileOutputStream(file);
try {
stream.write("text-to-write".getBytes());
} finally {
stream.close();
}
或者使用Google Guava
String contents = Files.toString(file,StandardCharsets.UTF_8);
将文件读取到字符串
int length = (int) file.length();
byte[] bytes = new byte[length];
FileInputStream in = new FileInputStream(file);
try {
in.read(bytes);
} finally {
in.close();
}
String contents = new String(bytes);
或者,如果你使用的是Google Guava
String contents = Files.toString(file,"UTF-8");
为了完整,我会提到
String contents = new Scanner(file).useDelimiter("\\A").next();
它不需要库,但基准测试比其他选项慢50%-400%(在我的Nexus 5的各种测试中)。
注释
对于这些策略中的每一个,都会要求你捕获IOException。
Android上的默认字符编码是UTF-8。
如果你使用外部存储,则需要添加到清单中:
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
要么
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
写入权限意味着读取权限,因此你不需要两者。
#3 热门回答(26 赞)
public static void writeStringAsFile(final String fileContents, String fileName) {
Context context = App.instance.getApplicationContext();
try {
FileWriter out = new FileWriter(new File(context.getFilesDir(), fileName));
out.write(fileContents);
out.close();
} catch (IOException e) {
Logger.logError(TAG, e);
}
}
public static String readFileAsString(String fileName) {
Context context = App.instance.getApplicationContext();
StringBuilder stringBuilder = new StringBuilder();
String line;
BufferedReader in = null;
try {
in = new BufferedReader(new FileReader(new File(context.getFilesDir(), fileName)));
while ((line = in.readLine()) != null) stringBuilder.append(line);
} catch (FileNotFoundException e) {
Logger.logError(TAG, e);
} catch (IOException e) {
Logger.logError(TAG, e);
}
return stringBuilder.toString();
}