Android开发之文件操作详解

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
<TextView
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:text="@string/filename"
  />
 <EditText
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:id="@+id/filename"
  />
  <TextView
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:text="@string/content"
  />
 <EditText
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:id="@+id/content"
  android:minLines="3"
  />
  <Button
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="@string/button"
   android:id="@+id/button"/>
</LinearLayout>

/* AUTO-GENERATED FILE. DO NOT MODIFY.
 *
 * This class was automatically generated by the
 * aapt tool from the resource data it found. It
 * should not be modified by hand.
 */
package org.lxh.file;
public final class R {
  public static final class attr {
  }
  public static final class drawable {
    public static final int icon=0x7f020000;
  }
  public static final class id {
    public static final int button=0x7f050002;
    public static final int content=0x7f050001;
    public static final int filename=0x7f050000;
  }
  public static final class layout {
    public static final int main=0x7f030000;
  }
  public static final class string {
    public static final int app_name=0x7f040001;
    public static final int button=0x7f040004;
    public static final int content=0x7f040003;
    public static final int failure=0x7f040006;
    public static final int filename=0x7f040002;
    public static final int hello=0x7f040000;
    public static final int success=0x7f040005;
  }
}

package org.lxh.service;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import android.content.Context;
import android.util.Log;
public class FileService {
  private Context context;
  public FileService(Context context) { //通过构造方法传入context
    this.context = context;
  }
  //保存文件
  public void saveFile(String filename,String content) throws Exception{ //异常交给调用处处理
    FileOutputStream out=context.openFileOutput(filename, Context.MODE_PRIVATE);
    out.write(content.getBytes());
    out.close();
  }
  public String readFile(String filename) throws Exception{ //异常交给调用处处理
    FileInputStream in=context.openFileInput(filename);
    byte b[]=new byte[1024];
    int len=0;
    ByteArrayOutputStream array=new ByteArrayOutputStream();
    while((len=in.read(b))!=-1){ //开始读取文件
      array.write(b,0,len);
    }
    byte data[]=array.toByteArray(); //把内存里的数据读取出来
    in.close(); //每个流都必须关闭
    array.close();
    return new String(data); //把byte数组转换为字符串并返回
  }
}

package org.lxh.test;
import org.lxh.service.FileService;
import android.test.AndroidTestCase;
import android.util.Log;
public class Test extends AndroidTestCase {
  public static final String TAG = "Test";
  public void testSave() {
    FileService service = new FileService(this.getContext());
    try {
      service.saveFile("01.txt", "hello");
    } catch (Exception e) {
      Log.i(TAG, e.getMessage());
    }
  }
  public void testRead() {
    FileService service = new FileService(this.getContext());
    try {
      Log.i(TAG,service.readFile("01.txt"));
    } catch (Exception e) {
      Log.e(TAG, e.getMessage());
    }
  }
}

package org.lxh.file;
import org.lxh.service.FileService;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class FileActivity extends Activity {
  private FileService service;
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    service=new FileService(this);
    Button button=(Button)findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {
      public void onClick(View v) {
        EditText filename=(EditText)findViewById(R.id.filename);
        EditText content=(EditText)findViewById(R.id.content);
        try {
          service.saveFile(filename.getText().toString(), content.getText().toString());
          Toast.makeText(FileActivity.this, R.string.success, 1).show();
        } catch (Exception e) {
          Toast.makeText(FileActivity.this, R.string.failure, 1).show();
          Log.e("FileActivity", e.getMessage());
        }
      }
    });
  }
}

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <string name="hello">Hello World, FileActivity!</string>
  <string name="app_name">文件的读取</string>
  <string name="filename">输入文件名称</string>
  <string name="content">输入文件内容</string>
  <string name="button">保存</string>
  <string name="success">文件保存成功</string>
  <string name="failure">文件保存失败</string>
</resources>