Android菜鸟笔记04:文件的保存与读取

文件保存：

一，界面：

二，输入文件名、文件内容，按“保存”，将文件保存到默认目录(data/应用包名/files/)。

 

三，知识点：利用上下文对象提供的openFileOutput实现文件保存

 

四，代码：

MainActivity.java :

package im.qvod.file;

import im.qvod.service.FileService;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) this.findViewById(R.id.button);
        button.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                EditText filenameText = (EditText) findViewById(R.id.filename);
                EditText filecontentText = (EditText) findViewById(R.id.filecontent);
                String filename = filenameText.getText().toString();
                String filecontent = filecontentText.getText().toString();
                FileService service = new FileService(getApplicationContext());
                try {
                    service.save(filename, filecontent);
                    Toast.makeText(getApplicationContext(), R.string.success,
                            Toast.LENGTH_LONG).show();
                } catch (Exception e) {
                    Toast.makeText(getApplicationContext(), R.string.fail,
                            Toast.LENGTH_LONG).show();
                    e.printStackTrace();
                }

            }
        });
    }

    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

FileService.java:

package im.qvod.service;

import java.io.FileOutputStream;
import android.content.Context;

public class FileService {
    private Context context;
    
    public FileService(Context context) {
        super();
        this.context = context;
    }

    public void save(String filename, String filecontent) throws Exception {
        FileOutputStream outputStream = context.openFileOutput(filename,
                Context.MODE_PRIVATE);
        outputStream.write(filecontent.getBytes());
        outputStream.close();
    }

}

 

文件读取:

 

/**
     * 读取文件数据
     * @param filename
     * @return
     * @throws Exception
     */
    public String read(String filename) throws Exception {
        FileInputStream inputStream = context.openFileInput(filename);
        ByteArrayOutputStream arrayOutputStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = 0;
        while ((len = inputStream.read(buffer)) != -1) {
            arrayOutputStream.write(buffer, 0, len);
        }
        byte[] data = arrayOutputStream.toByteArray();// 得到存放在内存中的数据
        return new String(data);
        

    }