Android file内部存储

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通过file=openFileOutput()获得，将数据存储在data/data/+包名+files下面。

代码如下：

MainActivity.java:

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

import com.example.helloworld.R;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

public class FileActivity extends AppCompatActivity {

    private EditText mEtName;

    private Button mBtnSave,mBtnShow;

    private TextView mTvContent;

    private final String mFileName = "test.txt";

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_file);

        mEtName = findViewById(R.id.et_name);

        mBtnSave = findViewById(R.id.btn_save);

        mBtnShow = findViewById(R.id.btn_show);

        mTvContent = findViewById(R.id.tv_content);

        mBtnSave.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                save(mEtName.getText().toString());

            }

        });

        mBtnShow.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                mTvContent.setText(read());

            }

        });

    }

    //存储数据

    private void save(String content){

        FileOutputStream fileOutputStream = null;

        try {

            fileOutputStream = openFileOutput(mFileName,MODE_PRIVATE);

            fileOutputStream.write(content.getBytes());

        } catch (IOException e) {

            e.printStackTrace();

        } finally {

            if(fileOutputStream != null){

                try{

                    fileOutputStream.close();

                } catch (IOException e) {

                    e.printStackTrace();

                }

            }

        }

    }

    //读取数据

    private String read(){

        FileInputStream fileInputStream = null;

        try {

            fileInputStream = openFileInput(mFileName);

            byte[] buff = new byte[1024];

            //用StringBuilder来实现字符串拼接

            StringBuilder sb = new StringBuilder();

            int len = 0;

            while((len = fileInputStream.read(buff)) > 0){

                sb.append(new String(buff,0,len));

            }

            return sb.toString();

        } catch (IOException e) {

            e.printStackTrace();

        }finally {

            if(fileInputStream != null){

                try{

                    fileInputStream.close();

                } catch (IOException e) {

                    e.printStackTrace();

                }

            }

        }

        return null;

    }

}