直接上代码：

package com.example.test; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import android.os.Bundle; import android.os.Environment; import android.app.Activity; import android.widget.Toast; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //要保存的文件名和文件内容 String fileName = "test.txt"; String content = "This is a test."; //判断sdcard是否存在 String state = Environment.getExternalStorageState(); if(state.equals(Environment.MEDIA_MOUNTED)) { //获取SDCard目录 File sdcardPath = Environment.getExternalStorageDirectory(); File file = new File(sdcardPath, fileName); FileOutputStream fos; try { fos = new FileOutputStream(file); fos.write(content.getBytes()); fos.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show(); } else { Toast.makeText(this, "sdcard不存在获取不可写入", Toast.LENGTH_SHORT).show(); } } }