android sd卡读写

将文件存在sd卡中和存在手机中的思路相同就是路径不同,注意看类中的到sd卡路径的注释

package cn.lee.data;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import cn.lee.Manager.DataManager;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class AboutDateActivity extends Activity {
    private EditText fileNameEditText;
    private EditText fileContentEditText;
    private EditText readfileContentEditText;
    private Button button;
    private Button readButton;
    private static final String TAGSTRING = "AboutDateActivity";

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        button = (Button) this.findViewById(R.id.button);
        readButton = (Button) this.findViewById(R.id.readButton);
        fileNameEditText = (EditText) this.findViewById(R.id.fileName);
        fileContentEditText = (EditText) this.findViewById(R.id.fileContent);
        readfileContentEditText = (EditText) this
                .findViewById(R.id.readfileContent);

        // 读取
        readButton.setOnClickListener(onClickListener);
        // 保存
        button.setOnClickListener(onClickListener);
    }

    /**
     * 由于这个内部实现类是一个接口的实例 所以这里把他提取出来 作为一个成员变量 2010-04-18
     */
    private View.OnClickListener onClickListener = new View.OnClickListener() {
        /**
         * 由于button的父类是view 所以这里的onclick的参数传来的view v就可以找到这个button
         */
        public void onClick(View v) {
            Button button = (Button) v;// 将父类view强转成子类button
            int info = R.string.sus;
            String fileNameString = fileNameEditText.getText().toString();

            /**
             * 判断sd卡是否存在 Environment.getExternalStorageState() 得到sd卡当前的状态
             *
             * getExternalStorageState() returns MEDIA_MOUNTED if the
             * media is present and mounted at its mount point with
             * read/write access. 如果返回 MEDIA_MOUNTED表示外部存储设备存在。并且有读写的权限(因为sd卡有写保护 如果写保护关闭也是没有权限读写的)
             */

            if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
                if ("".equals(fileNameString)) {
                    info = R.string.sdNotExit;
                } else {
                    FileOutputStream fileOutputStream = null;
                    FileInputStream fileInputStream = null;
                    try {
                        /**
                         * Environment.getExternalStorageDirectory();
                         * 得到外存储设备的路径
                         *
                         */
                        File file = new File(Environment.getExternalStorageDirectory(),fileNameString);

                        switch (button.getId()) {
                        case R.id.button: {// 保存
                            String fileContentString = fileContentEditText.getText().toString();

                            fileOutputStream = new FileOutputStream(file);
                            DataManager.saveDate(fileOutputStream,fileContentString);
                            break;
                        }

                        case R.id.readButton: {//读取
                            fileInputStream = new FileInputStream(file);
                            String contentString = DataManager.readDate(fileInputStream);
                            readfileContentEditText.setText(contentString);
                            break;
                        }
                        default:
                            break;
                        }

                    } catch (Exception e) {
                        // TODO Auto-generated catch block
                        Log.i(TAGSTRING, e.toString());
                        info = R.string.infor;
                    } finally {
                        try {
                            if (fileOutputStream != null) {
                                fileOutputStream.close();
                            }
                            if (fileInputStream != null) {
                                fileInputStream.close();
                            }

                        } catch (IOException e) {

                            Log.i(TAGSTRING, e.toString());
                            info = R.string.infor;
                        }
                    }

                }
            } else {
                info = R.string.infor;
            }
            Toast.makeText(AboutDateActivity.this, info, 1).show();
        }

    };
}