Android文件存储和读取方式

Android文件存储和读取方式主要用到两个方法，第一个是文件写入方法OpenFileOutput（）；返回的是FileOutputStream对象，第二个是文件读取方法OpenFileInput（）；返回的是FileIntputStream对象。

文件写入方式：

• 1.首先通过OpenFileOutput（）方法，这个方法传人两个参数，第一个参数是文件名，第二个参数是文件的操作模式，获得FileOutputSteam对象

FileOutputStream out = OpenFileOutput("content",Context.MODE_PRIVATE);

• 2.通过Java I/O流进行读写操作

String data="Hello World!"
BufferWriter writer = new BufferWrite(new OutputStreamWriter(out));
writer.write(data);

文件读取方式：

• 1.首先通过OpenFileInput()方法，这个方法传入一个参数，文件名，获得FileInputStream对象

FileInputStream in = OpenFileInput("content");

• 2.通过Java I/O流进行读写操作

BufferReader reader = new BufferReader(new inputStreamReader(in));
StringBuilder data = new StringBuilder();
String line;
while((line=reader.readLine())!=null){
        data.append(line);
}

完整的Java代码

package com.example.kevin.filetest;

import android.app.Activity;
import android.os.Bundle;
import android.text.TextUtils;
import android.widget.EditText;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class MainActivity extends Activity {
    private EditText write;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        write = (EditText) findViewById(R.id.write);
        String inputText = load();
        //TextUtils.isEmpty判断字符是否null或空字符，是的就返回true
        if (!TextUtils.isEmpty(inputText)) {
            write.setText(inputText);
            write.setSelection(inputText.length());
            Toast.makeText(getApplicationContext(), "读取结果返回成功", Toast.LENGTH_LONG).show();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        String data = write.getText().toString();
        save(data);
    }

    //保存文件操作
    private void save(String data) {
        FileOutputStream out = null;
        BufferedWriter writer = null;
        try {
            out = openFileOutput("content", MODE_APPEND);
            writer = new BufferedWriter(new OutputStreamWriter(out));
            writer.write(data);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (writer != null) {
                    writer.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

        }

    }

    //读取文件操作
    private String load() {
        FileInputStream in = null;
        BufferedReader reader = null;
        StringBuilder content = new StringBuilder();
        try {
            in = openFileInput("content");
            reader = new BufferedReader(new InputStreamReader(in));
            String line = "";
            while ((line = reader.readLine()) != null) {
                content.append(line);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return content.toString();
    }
}