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今天学取出文本文件里的内容,还是修改原来项目的mainactivity.java文件package com.example.xinwei.filepersistencetest;
import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.widget.EditText;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
public class MainActivity extends AppCompatActivity {
private EditText edit;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edit=(EditText)findViewById(R.id.edit);
String inputText=load();
if(TextUtils.isEmpty(edit.getText())){
edit.setText(inputText);
edit.setSelection(inputText.length());
Toast.makeText(this, "Restoring succeeded", Toast.LENGTH_SHORT).show();
}
}
@Override
protected void onDestroy() {
super.onDestroy();
String inputText=edit.getText().toString();
save(inputText);
}
private void save(String inputText) {
FileOutputStream out=null;
BufferedWriter writer=null;
try {
out=openFileOutput("data", Context.MODE_PRIVATE);
writer=new BufferedWriter(new OutputStreamWriter(out));
writer.write(inputText);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally {
if(writer!=null){
try {
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public String load(){
FileInputStream in = null;
BufferedReader reader= null;
StringBuilder content = new StringBuilder();
try {
in = openFileInput("data");
reader = new BufferedReader(new InputStreamReader(in));
String line="";
while((line=reader.readLine())!=null){
content.append(line);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally {
if(reader!=null){
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return content.toString();
}
}
这里的load()函数就是取出文件的方法,也是依靠这个类里内置的openFileInput()方法,非常方便,这次我们一打开程序就会出现上次我们输入的内容了 |