Android SD卡读取简单操作

Posted 2020-07-31 学无止境

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();
			}
			
		}
	}

}
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布局文件
简单的两个按钮，没什么好说的