android的文件操作

目前，机会搜有的设备都会涉及到文件的操作，例如什么电脑，手机等设备。android的文件操作和电脑是比较类似的，既可以存储在手机内置的存储器里也可以是sd卡。在这次的博客里主要介绍在手机内置存储器里的文件操作。

一.开发流程

（1）界面的设计

（2）设计android的业务层

（3）单元测试

（4）设置android的控制器层

二.开发步骤

（1）设计软件界面

<?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>

这里也把R文件给大家看看

/* 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;
    }
}

(2)设计业务层

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
	}
}

下面开始做单元测试，要添加的环境就不说了

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());
		}

	}
}

看一下运行之后的效果

单元测试通过了，下面来看下在模拟器上的效果，在这之前要先看下下面的代码

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());
				}
			}
		});
        
    }
}

如果保存成功就给用户一个吐司通知

下面把strings.xml的代码也贴出来

<?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>

如果对上面写的有疑问可以给我留言。