package com.example.sdcardtest;import java.io.BufferedReader;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStreamReader;import java.io.RandomAccessFile;import android.app.Activity;import android.os.Bundle;import android.os.Environment;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;public class MainActivity extends Activity {			final String FILE_NAME = "/baidu/hello.txt";	@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_main);				Button read = (Button) findViewById(R.id.read);		Button write = (Button) findViewById(R.id.write);				final EditText edit1 = (EditText) findViewById(R.id.editText1);		final EditText edit2 = (EditText) findViewById(R.id.editText2);				//为write事件绑定监听器		write.setOnClickListener(new OnClickListener() {						public void onClick(View v) {				write(edit1.getText().toString());				edit1.setText("");							}		});				//为read事件绑定监听器		read.setOnClickListener(new OnClickListener() {						public void onClick(View v) {				edit2.setText(read());			}		});					}			public String read(){		if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){			File sdCardDir = Environment.getExternalStorageDirectory();			try {				FileInputStream fis = new FileInputStream(sdCardDir.getCanonicalPath() + FILE_NAME);				BufferedReader br = new BufferedReader(new InputStreamReader(fis));				StringBuilder sb = new StringBuilder("");								String line = null;				while( (line = br.readLine()) != null ){					sb.append(line);				}				br.close();				return sb.toString();			} catch (FileNotFoundException e) {				e.printStackTrace();			} catch (IOException e) {				e.printStackTrace();			}					}		return null;	}		public void write(String content){		if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){			RandomAccessFile raf = null;			try {				//获取sd卡的目录				File sdCardDir = Environment.getExternalStorageDirectory();				File targetFile = new File(sdCardDir.getCanonicalFile() + FILE_NAME);								raf = new RandomAccessFile(targetFile, "rw");				raf.seek(targetFile.length());				raf.write(content.getBytes());							} catch (IOException e) {				e.printStackTrace();			}						try {				raf.close();			} catch (IOException e) {				e.printStackTrace();			}					}	}}=====================布局文件简单的两个按钮，没什么好说的