android读写sd卡操作写入数据读取数据示例
代码如下:
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.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.app.Activity;
public class MainActivity extends Activity {
final String FILE_NAME = "/lxp.bin";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button write = (Button) findViewById(R.id.main_btn1);
Button read = (Button) findViewById(R.id.main_btn2);
final EditText edit1 = (EditText) findViewById(R.id.main_edit1);
final EditText edit2 = (EditText) findViewById(R.id.main_edit2);
write.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
write(edit1.getText().toString().trim());
edit1.setText("");
}
});
read.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
edit2.setText(read());
}
});
}
private void write(String content){
try {
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
//获取SD卡的目录
File sdCardDir = Environment.getExternalStorageDirectory();
File targetFile = new File(sdCardDir.getCanonicalPath() + FILE_NAME);
//以指定文件创建RandomAccessFile对象
RandomAccessFile raf = new RandomAccessFile(targetFile, "rw");
//将文件记录指针移动到最后
raf.seek(targetFile.length());
//输出文件内容
raf.write(content.getBytes());
raf.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
private String read(){
try {
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
//获得SD卡对应的存储目录
File sdCardDir = Environment.getExternalStorageDirectory();
//获取指定文件对应的输入流
FileInputStream fis = new FileInputStream(sdCardDir.getCanonicalPath() + FILE_NAME);
//将指定输入流包装成BufferReader
BufferedReader br = new BufferedReader(new InputStreamReader(fis));
StringBuilder sb = new StringBuilder("");
String line = null;
//循环读取文件内容
while((line = br.readLine()) != null){
sb.append(line);
}
br.close();
return sb.toString();
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
最后别忘了在AndroidManafest.xml中增加访问读取SD的权限。
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