1、当前是把文件保存当前手机的app的data目录下
我们来看看操作保存文件的业务类
package contract.test.savafileapplication; import android.content.Context; import java.io.ByteArrayOutputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; public class FileService { private Context context; public FileService(Context context) { this.context = context; } public void saveFile(String fileName, String fileContext) throws Exception { FileOutputStream fileOutputStream = context.openFileOutput(fileName,Context.MODE_WORLD_READABLE); fileOutputStream.write(fileContext.getBytes()); fileOutputStream.close(); } public String readFile(String filename) throws IOException { FileInputStream fileInputStream = context.openFileInput(filename); byte[] bytes = new byte[1024]; ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); /*byte是基本数据类型 如int类型 Byte是byte的包装类*/ int len = 0; while ((len = fileInputStream.read(bytes))!=-1) { byteArrayOutputStream.write(bytes,0,len); } byteArrayOutputStream.close(); fileInputStream.close(); String str = new String(byteArrayOutputStream.toString()); return str; } }
openFileInput保存文件有四种类型:
openFileOutput(“a.txt”,Context.MODE_WORLD_READABLE)方法第一个参数是文件名,若不存在这个文件,则自动创建,第二个参数是操作模式共四种:
Context.MODE_PRIVATE = 0
Context.MODE_APPEND = 32768
Context.MODE_WORLD_READABLE = 1
Context.MODE_WORLD_WRITEABLE = 2
Context.MODE_PRIVATE:为默认操作模式,代表该文件是私有数据,只能被应用本身访问,在该模式下,写入的内容会覆盖原文件的内容,如果想把新写入的内容追加到原文件中。可以使用Context.MODE_APPEND
Context.MODE_APPEND:模式会检查文件是否存在,存在就往文件追加内容,否则就创建新文件。
Context.MODE_WORLD_READABLE和Context.MODE_WORLD_WRITEABLE用来控制其他应用是否有权限读写该文件。
MODE_WORLD_READABLE:表示当前文件可以被其他应用读取;MODE_WORLD_WRITEABLE:表示当前文件可以被其他应用写入。
如果希望文件被其他应用读和写,可以传入:
openFileOutput(“itcast.txt”, Context.MODE_WORLD_READABLE + Context.MODE_WORLD_WRITEABLE);
activity的代码是:
package contract.test.savafileapplication; import android.app.Activity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; import android.widget.Toast; import java.io.IOException; public class MyActivity extends Activity { private Button save , show; private EditText filename, filecontext; private TextView showContext; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_my); save = (Button)this.findViewById(R.id.saveButton); show = (Button)this.findViewById(R.id.showButton); filename = (EditText)this.findViewById(R.id.fileName_ET); filecontext = (EditText)this.findViewById(R.id.saveContext_ET); showContext = (TextView)this.findViewById(R.id.showConTextView); save.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { String name = filename.getText().toString(); String context = filecontext.getText().toString(); FileService fileService = new FileService(getApplicationContext()); try { fileService.saveFile(name,context); Toast.makeText(getApplicationContext(),"文件保存成功!",Toast.LENGTH_LONG).show(); } catch (Exception e) { Toast.makeText(getApplicationContext(),"文件保存失败!",Toast.LENGTH_LONG).show(); e.printStackTrace(); } } }); show.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { FileService fileService = new FileService(getApplicationContext()); String name = filename.getText().toString(); try { String str = fileService.readFile(name); Toast.makeText(getApplicationContext(),"文件读取成功!",Toast.LENGTH_LONG).show(); showContext.setText(str); } catch (IOException e) { e.printStackTrace(); Toast.makeText(getApplicationContext(),"文件读取失败!",Toast.LENGTH_LONG).show(); } } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.my, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } }
xml的代码:
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="请输入要保存的文件名:" /> <EditText android:id="@+id/fileName_ET" android:layout_width="fill_parent" android:layout_height="50dp" android:hint="请输入要保存的文件名!" /> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="请您输入要保存的内容:" /> <EditText android:id="@+id/saveContext_ET" android:layout_width="fill_parent" android:layout_height="wrap_content" android:hint="请您在此处输入文件内容!" /> <Button android:id="@+id/saveButton" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="save" /> <Button android:id="@+id/showButton" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="show" /> <TextView android:id="@+id/showConTextView" android:layout_width="fill_parent" android:layout_height="wrap_content" /> </LinearLayout>