写文件

//获取SD卡得存储状态
state= Environment.getExternalStorageState();
//获取SD卡存储位置
f=Environment.getExternalStorageDirectory();
File ff=null;

if(state.equals(Environment.MEDIA_MOUNTED)){
    ff=new File(f.getAbsolutePath(),"cy.txt");
    if(!ff.exists()){
        try {
            ff.createNewFile();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }



}

try {
    FileWriter fw=new FileWriter(ff);
    fw.write(s);
    fw.flush();
    fw.close();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}