实现数据存储在SD卡上
实验效果
主要代码
package com.example.savesd;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.RandomAccessFile;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
private Button btnWrite, btnRead;
private EditText edtContent;
private TextView tvResult;
private static final String FILE_NAME = "test.txt";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edtContent = (EditText) this.findViewById(R.id.edtContent);
tvResult = (TextView) this.findViewById(R.id.tvResult);
btnRead = (Button) this.findViewById(R.id.btnRead);
btnWrite = (Button) this.findViewById(R.id.btnWrite);
btnWrite.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
System.out.println("往SDCard里写数据");
// 先判断是否有SDCard
System.out.println("Environment.getExternalStorageState():"
+ Environment.getExternalStorageState());
System.out.println("Environment.MEDIA_MOUNTED:"
+ Environment.MEDIA_MOUNTED);
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
String content = edtContent.getText().toString();
try {
// 获取SDcard路径
File sdCardDir = Environment
.getExternalStorageDirectory();
// SDCard目录：/mnt/sdcard
String sdcardPath = sdCardDir.getAbsolutePath();
System.out.println("sdCardDir.getAbsolutePath()"
+ sdCardDir.getAbsolutePath());
File file = new File(sdCardDir, FILE_NAME);
// File file = new File(sdcardPath
// + File.separator + FILE_NAME);
// 以指定文件创建RandomAccessFile对象
RandomAccessFile raf = new RandomAccessFile(file, "rw");
// 将文件记录指针移动最后
raf.seek(file.length());
// 输出文件内容
raf.write(content.getBytes());
raf.close();
} catch (Exception e) {
// TODO: handle exception
}
}
}
});
btnRead.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
// 获取SDcard路径
StringBuilder sb = new StringBuilder();
try {
File sdCardDir = Environment
.getExternalStorageDirectory();
File file = new File(sdCardDir, FILE_NAME);
InputStream inputStream = new FileInputStream(file);
int len = 0;
byte[] buffer = new byte[1024];
while ((len = inputStream.read(buffer)) != -1) {
sb.append(new String(buffer, 0, len));
}
tvResult.setText(sb.toString());
// 关闭流
inputStream.close();
} catch (Exception e) {
// TODO Auto-generated catch block
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;
}
}