Android中的文件存储练习

  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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