Android的文件存储（写入和读取）

package com.t20.fileop;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import android.os.Bundle;import android.app.Activity;import android.content.Context;import android.view.View;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends Activity {private EditText etContent;private TextView tvContent;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//输入框etContent=(EditText) findViewById(R.id.etContent);//文本框tvContent=(TextView) findViewById(R.id.tvContent);}/** * 写入文件 * @param v */public void write(View v){//文件输出流FileOutputStream out=null;//缓冲写入器BufferedWriter writer=null;String content=etContent.getText().toString();if(content.isEmpty()){Toast.makeText(MainActivity.this, "请输入内容", Toast.LENGTH_SHORT).show();return;}try {//安卓封装好的文件写入文件方法out=openFileOutput("data.txt", Context.MODE_PRIVATE);//权限：-rwx------（只能自己读写）writer=new BufferedWriter(new OutputStreamWriter(out));//------------------文件名-------------写入模式-----//开始写入writer.write(content);Toast.makeText(MainActivity.this, "文件写入成功！", Toast.LENGTH_SHORT).show();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(writer!=null){writer.close();}if(out!=null){out.close();}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}/** * 保存文件到SD卡(写入SD卡需要权限，在AndroidManifest.xml中设置android.permission.WRITE_EXTERNAL_STORAGE) * @param v */public void writeSD(View v){//文件输出流FileOutputStream out=null;String content=etContent.getText().toString();if(content.isEmpty()){Toast.makeText(MainActivity.this, "请输入内容", Toast.LENGTH_SHORT).show();return;}//设置文件路径File file=new File(getExternalFilesDir(null), "/data.txt");try {out=new FileOutputStream(file);out.write(content.getBytes());Toast.makeText(MainActivity.this, "成功保存到SD卡！", Toast.LENGTH_SHORT).show();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(out!=null){out.close();}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}/** * 读取文件 * @param v */public void read(View v){//文件输入流FileInputStream in=null;//缓冲读取器BufferedReader reader=null;StringBuilder builder=new StringBuilder();try {//安卓封装好的文件读取文件方法in=openFileInput("data.txt");reader=new BufferedReader(new InputStreamReader(in));//使用流逐行读取String line="";while ((line=reader.readLine())!=null) {builder.append(line);}tvContent.setText(builder.toString());} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(reader!=null){reader.close();}if(in!=null){in.close();}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}/** * 从SD卡中读取文件(读取SD卡需要权限，在AndroidManifest.xml中设置android.permission.READ_EXTERNAL_STORAGE) * @param v */public void readSD(View v){//文件输入流FileInputStream in=null;//设置文件路径File file=new File(getExternalFilesDir(null), "/data.txt");try {in=new FileInputStream(file);//使用缓冲来读byte[] buf=new byte[1024];//每1024字节读一次StringBuilder builder=new StringBuilder();while (in.read(buf)!=-1) {builder.append(new String(buf).trim());}tvContent.setText(builder.toString());} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(in!=null){in.close();}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}
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