Android中对SD卡的读取与写入

最新推荐文章于 2021-05-25 21:29:01 发布

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本文介绍了一种在安卓设备上实现SD卡读写的简单方法。通过示例代码展示了如何请求必要的权限、检查SD卡状态以及进行文件的写入与读取操作。

对安卓SD卡的读取与写入并不复杂，这里直接上主要的代码：
当然一定要记得在清单文件中设置对读取与写入的权限：

 <!-- 读取 -->
 <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
 <!-- 写入权限 -->
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
  <!-- 创建与删除权限 -->
 <uses-permission android:name="android.permission.MOUNT_FORMAT_FILESYSTEMS" />

import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

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

public class WriteReadSD extends AppCompatActivity {

    private Button write,read;
    private EditText editText;
    private TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.write_read_sd);
        write = (Button)findViewById(R.id.write);
        read = (Button)findViewById(R.id.read);
        editText = (EditText)findViewById(R.id.edit);
        textView = (TextView)findViewById(R.id.show);
        write.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isSD()){
                    String str = editText.getText().toString();
                    File file = Environment.getExternalStorageDirectory();
                    try {
                        File file1 = new File(file.getCanonicalPath()+"/user.txt");
                        FileOutputStream fop = new FileOutputStream(file1);
                        fop.write(str.getBytes());
                        fop.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
        read.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isSD()){
                    StringBuffer stringBuffer = new StringBuffer();
                    try {
                        File file = new File(Environment.getExternalStorageDirectory()
                        .getCanonicalPath()+"/user.txt");
                        if (file.exists()){
                            // 打开文件输入流
                            FileInputStream fip = new FileInputStream(file);
                            BufferedReader reader = new BufferedReader(new InputStreamReader(fip));
                            String str = "";
                            while ((str=reader.readLine())!=null){
                                stringBuffer.append(str);
                            }
                            reader.close();
                            textView.setText(stringBuffer);

                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
    }

    //判断SD卡是否准备
    private boolean isSD(){
        String state = Environment.getExternalStorageState();
        if (Environment.MEDIA_MOUNTED.equals(state)){
            return true;
        }
        return false;
    }


}