Android中的文件存储练习
16lz
2022-05-26
1 package com.example.filedemo1; 2 3 import java.io.BufferedReader; 4 import java.io.BufferedWriter; 5 import java.io.ByteArrayOutputStream; 6 import java.io.File; 7 import java.io.FileInputStream; 8 import java.io.FileNotFoundException; 9 import java.io.FileOutputStream; 10 import java.io.FileReader; 11 import java.io.FileWriter; 12 import java.io.IOException; 13 14 import android.os.Bundle; 15 import android.app.Activity; 16 import android.util.Log; 17 import android.view.Menu; 18 import android.view.View; 19 import android.view.View.OnClickListener; 20 import android.widget.Button; 21 import android.widget.EditText; 22 import android.widget.TextView; 23 import android.widget.Toast; 24 25 public class MainActivity extends Activity { 26 // private BufferedWriter bufferedWriter; 27 // private BufferedReader bufferedReader; 28 private EditText edt; 29 private Button bt; 30 private TextView tv; 31 @Override 32 protected void onCreate(Bundle savedInstanceState) { 33 super.onCreate(savedInstanceState); 34 setContentView(R.layout.activity_main); 35 // File file = new File("/mnt/sdcard/text"); 36 // if(!file.exists()){ 37 // try { 38 // file.createNewFile(); 39 // Toast.makeText(MainActivity.this, "创建文件成功！", Toast.LENGTH_SHORT).show(); 40 // } catch (IOException e) { 41 // // TODO Auto-generated catch block 42 // e.printStackTrace(); 43 // } 44 // }else{ 45 // Toast.makeText(MainActivity.this, "文件已存在！", Toast.LENGTH_SHORT).show(); 46 // } 47 //// file.delete(); 48 // try { 49 // bufferedWriter = new BufferedWriter(new FileWriter("/mnt/sdcard/text",true)); 50 // bufferedWriter.write("第一行！"); 51 // bufferedWriter.newLine(); 52 // bufferedWriter.write("第二行！"); 53 // bufferedWriter.flush(); 54 // bufferedWriter.close(); 55 // bufferedReader = new BufferedReader(new FileReader("/mnt/sdcard/text")); 56 // Log.i("info",bufferedReader.readLine()); 57 // Log.i("info",bufferedReader.readLine()); 58 // } catch (IOException e) { 59 // // TODO Auto-generated catch block 60 // e.printStackTrace(); 61 // } 62 // File file = this.getFilesDir(); 63 // Log.i("info", file.toString()); 64 // File file = this.getCacheDir(); 65 // Log.i("info", file.toString()); 66 // File file = this.getDir("imooc", MODE_PRIVATE); 67 // Log.i("info", file.toString()); 68 // File file = this.getDir("mirror", MODE_PRIVATE); 69 // Log.i("info", file.toString()); 70 // File file = this.getExternalCacheDir(); 71 // Log.i("info", file.toString()); 72 edt = (EditText) findViewById(R.id.editText1); 73 bt = (Button) findViewById(R.id.write); 74 tv = (TextView) findViewById(R.id.contentvalue); 75 // try { 76 // bufferedWriter = new BufferedWriter(new FileWriter("/mnt/sdcard/text")); 77 // bufferedReader = new BufferedReader(new FileReader("/mnt/sdcard/text")); 78 // bt.setOnClickListener(new OnClickListener() { 79 // 80 // @Override 81 // public void onClick(View v) { 82 // // TODO Auto-generated method stub 83 // String str = edt.getText().toString(); 84 // Log.i("info", str); 85 // if(str != null) { 86 // try { 87 // bufferedWriter.write("a"); 88 // bufferedWriter.flush(); 89 // bufferedWriter.close(); 90 // str = bufferedReader.readLine(); 91 // Log.i("info", str); 92 // if(str!= null){ 93 // Log.i("info", str); 94 // tv.append(str); 95 // Log.i("info", str); 96 // str = bufferedReader.readLine(); 97 // } 98 //// Log.i("info", str); 99 // bufferedReader.close();100 // } catch (IOException e) {101 // // TODO Auto-generated catch block102 // e.printStackTrace();103 // } 104 // }105 // }106 // });107 // } catch (IOException e) {108 // // TODO Auto-generated catch block109 // e.printStackTrace();110 // }111 bt.setOnClickListener(new OnClickListener() {112 113 @Override114 public void onClick(View v) {115 // TODO Auto-generated method stub116 try {117 writeFiles(edt.getText().toString());118 tv.setText(readFiles());119 } catch (IOException e) {120 // TODO Auto-generated catch block121 e.printStackTrace();122 }123 }124 });125 }126 127 public void writeFiles(String content) throws IOException {128 FileOutputStream fos = openFileOutput("a.txt", MODE_PRIVATE);129 fos.write(content.getBytes());130 fos.close();131 }132 133 public String readFiles() throws IOException {134 String content = null;135 FileInputStream fis = openFileInput("a.txt");136 ByteArrayOutputStream baos = new ByteArrayOutputStream();137 byte[] buffer = new byte[1024];138 int len = 0;139 while((len = fis.read(buffer)) != -1) {140 baos.write(buffer,0,len);141 }142 content = baos.toString();143 fis.close();144 baos.close();145 return content; 146 }147 }
xml布局中有一个EditText，一个Button和一个TextView。自己在看教程之前先写了一个，失败。下面是教程中给出的方法。中间因为搞错了组件id，浪费了很多时间。
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