android应用开发详解（二十）---------------------file

1、工程目录

2、MainActivity.java

package com.example.test_file;

import java.io.FileInputStream;
import java.io.FileOutputStream;

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;

public class MainActivity extends Activity {
	private EditText myEdit01, myEdit02;
	private Button myBtn01, myBtn02;
	// 文件名称字符串常量
	private static final String FILE_NAME = "temp.txt";

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		myBtn01 = (Button) findViewById(R.id.button01);
		myBtn02 = (Button) findViewById(R.id.button02);
		myEdit01 = (EditText) findViewById(R.id.edit01);
		myEdit02 = (EditText) findViewById(R.id.edit02);
		myBtn01.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				// 写内容
				write(myEdit01.getText().toString());

			}
		});
		myBtn02.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				// 读内容
				myEdit02.setText(read());

			}
		});
	}

	// 读文件方法
	private String read() {
		try {
			// 实例化文件输入流
			FileInputStream fis = openFileInput(FILE_NAME);
			// 定义缓存数组
			byte[] buffer = new byte[fis.available()];
			// 读到缓冲区
			fis.read(buffer);
			System.out.println("读取文件成功");
			return new String(buffer);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;

	}

	// 写文件方法
	private void write(String content) {
		try {
			// 实例化文件输出流
			FileOutputStream fos = openFileOutput(FILE_NAME, MODE_APPEND);
			// 写内容
			fos.write(content.getBytes());
			System.out.println("写入文件成功");
			// 关闭文件流
			fos.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}

3、main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/edit01"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:lines="4"
        android:text="" />

    <Button
        android:id="@+id/button01"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="写入文件" />

    <EditText
        android:id="@+id/edit02"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:lines="4"
        android:text="" />

    <Button
        android:id="@+id/button02"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="读取文件" />

</LinearLayout>